Patent Publication Number: US-2021162280-A1

Title: Mixed material golf club head

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This builds upon the disclosure provided in U.S. patent application Ser. No. 17/094,722, filed on Nov. 10, 2020, which is a continuation of U.S. patent application Ser. No. 16/252,349, filed on Jan. 18, 2019, now U.S. Pat. No. 10,828,543, issued Nov. 10, 2020, which claims the benefit of priority from U.S. Provisional Patent Application Nos. 62/619,631 filed 19 Jan. 2018; 62/644,319 filed 16 Mar. 2018; 62/702,996 filed 25 Jul. 2018; 62/703,305 filed 25 Jul. 2018; 62/718,857 filed 14 Aug. 2018; 62/770,000 filed 20 Nov. 2018; 62/781,509 filed 18 Dec. 2018; and 62/781,513 filed 18 Dec. 2018. U.S. patent application Ser. No. 16/252,349 is a continuation-in-part of U.S. patent application Ser. No. 15/901,081, filed on Feb. 21, 2018, now U.S. Pat. No. 10,300,354, issued May 28, 2019, which is a continuation of U.S. patent application Ser. No. 15/607,166, filed on May 26, 2017, now U.S. Pat. No. 9,925,432, issued March 27, 2018, which claims the benefit of priority from U.S. Provisional Patent No. 62/324,741, filed May 27, 2016. 
     This application is also a continuation-in-part of U.S. patent application Ser. No. 17/105,459, filed Nov. 25, 2020, which is a continuation-in-part of PCT Application No. PCT/US2020/043483, filed Jul. 24, 2020, which claims the benefit of priority from U.S. Provisional Patent Appl. No. 62/8878,263, filed Jul. 24, 2019. PCT Application No. PCT/US2020/043483is a continuation-in-part of U.S. patent application Ser. No. 16/789,261, filed Feb. 12, 2020, which is a continuation of U.S. patent application Ser. No. 16/215,474, filed on Dec. 10, 2018, now U.S. Pat. No. 10,596,427, issued Mar. 24, 2020, which claims the benefit of priority from U.S. Provisional Patent No. 62/596,677, filed on Dec. 8, 2017. U.S. patent application Ser. No. 17/105,459 is also a continuation-in-part of PCT Application No. PCT/US2020/047702, filed on Aug. 24, 2020, which claims the benefit of priority from U.S. Provisional Patent No. 62/891,158, filed on Aug. 23, 2019. U.S. patent application Ser. No. 17/105,459 also claims the benefit of priority from U.S. Provisional Application Nos. 62/940,799, filed Nov. 26, 2019; 62/976,229, filed Feb. 13, 2020; and 63/015,398, filed Apr. 24, 2020. 
     This application is also a continuation-in-part of U.S. patent application Ser. No. 16/724,176, filed on Sep. 24, 2020, which claims the benefit of priority from U.S. Provisional Patent Appl. Nos. 62/848,263, filed Jul. 24, 2019; 62/855,751, filed May 31, 2019; 62/784,190, Dec. 21, 2018; and 62/784,265, filed Dec. 21, 2018 U.S. patent application Ser. No. 16/724,176 is also a continuation-in-part of U.S. patent application Ser. No. 16/215,474, filed on Dec. 10, 2018, now U.S. Pat. No. 10,596,427, issued Mar. 24, 2020, which claims the benefit of priority from U.S. Provisional Patent No. 62/596,677, filed on Dec. 8, 2017. 
     This application also claims the benefit of priority from U.S. Provisional Patent Nos. 62/976,992, filed Feb. 14, 2020 and 63/050,692, filed July. 10, 2020. The disclosure of each of the above-referenced applications is incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a golf club head with a mixed material construction. 
     BACKGROUND 
     In an ideal club design, for a constant total swing weight, the amount of structural mass would be minimized (without sacrificing resiliency) to provide a designer with additional discretionary mass to specifically place in an effort to customize club performance. In general, the total of all club head mass is the sum of the total amount of structural mass and the total amount of discretionary mass. Structural mass generally refers to the mass of the materials that are required to provide the club head with the structural resilience needed to withstand repeated impacts. Structural mass is highly design-dependent, and provides a designer with a relatively low amount of control over specific mass distribution. Conversely, discretionary mass is any additional mass (beyond the minimum structural requirements) that may be added to the club head design for the sole purpose of customizing the performance and/or forgiveness of the club. There is a need in the art for alternative designs to all metal golf club heads to provide a means for maximizing discretionary weight to maximize club head moment of inertia (MOI) and lower/back center of gravity (COG). 
     While this provided background description attempts to clearly explain certain club-related terminology, it is meant to be illustrative and not limiting. Custom within the industry, rules set by golf organizations such as the United States Golf Association (USGA) or The R&amp;A, and naming convention may augment this description of terminology without departing from the scope of the present application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view of a mixed-material golf club head. 
         FIG. 2  is a schematic bottom view of a mixed-material golf club head. 
         FIG. 3  is a schematic exploded perspective view of an embodiment of a mixed-material golf club head similar to that shown in  FIG. 1 . 
         FIG. 4  is a schematic perspective view of an embodiment of a sole member of a mixed-material golf club head. 
         FIG. 5  is a schematic enlarged sectional view of a portion of the sole member of  FIG. 4 , taken along section  5 - 5 . 
         FIG. 6  is a schematic partial cross-sectional view of a joint structure of the golf club head of  FIG. 2 , taken along line  6 - 6 . 
         FIG. 7  is a schematic partial cross-sectional view of a joint structure of the golf club head of  FIG. 2 , taken along line  7 - 7 . 
         FIG. 8  is a schematic flow chart illustrating a method of manufacturing a mixed material golf club head. 
         FIG. 9  is a schematic top perspective view of a mixed material crown member. 
         FIG. 10  is a schematic bottom perspective view of a mixed material crown member. 
         FIG. 11  is a schematic perspective view of a thermoplastic composite front body of a golf club head. 
         FIG. 12  is a schematic partial cross-sectional view of a first embodiment of a golf club head having a thermoplastic composite front body, and taken along line  12 - 12  in  FIG. 11 . 
         FIG. 13  is a schematic partial cross-sectional view of a second embodiment of a golf club head having a thermoplastic composite front body, and taken along line  12 - 12  in  FIG. 11 . 
         FIG. 14  is a schematic rear view of a thermoplastic composite front body of a golf club head with a debossed channel surrounding the strike face. 
         FIG. 15  is a schematic top face view of a front body of a golf club head. 
         FIG. 16  is a schematic perspective view of a molded front body of a golf club head with a sprue and molding gate leading into the front body. 
         FIG. 17  is a reverse view of the front body of  FIG. 16   
         FIG. 18  is a schematic perspective view of the rear portion of a molded front body of a golf club head with a fabric reinforced composite inner surface. 
         FIG. 19  is a schematic flow chart illustrating a method of manufacturing a thermoplastic composite front body of a golf club head. 
         FIG. 20  is a schematic exploded view of a portion of a multi-layer thermoplastic crown. 
         FIG. 21  is a schematic top view of the multi-layer thermoplastic crown of  FIG. 20 . 
         FIG. 22  is a schematic exploded view of a portion of a multi-layer thermoplastic crown. 
         FIG. 23  is a schematic top view of the multi-layer thermoplastic crown of  FIG. 22 . 
         FIG. 24  is a schematic top view of a layer of a multi-layer thermoplastic crown or sole having a plurality of apertures. 
         FIG. 25  is a schematic top view of an embodiment of a layer of a multi-layer thermoplastic crown or sole having a plurality of apertures. 
         FIG. 26  is a schematic top view of an embodiment of a layer of a multi-layer thermoplastic crown or sole having a plurality of apertures. 
         FIG. 27  is a schematic top view of an embodiment of a layer of a multi-layer thermoplastic crown or sole having a plurality of apertures and weighted portions. 
         FIG. 28  is a schematic top view of an embodiment of a layer of a multi-layer thermoplastic crown or sole having an aperture and a plurality of weighted portions. 
         FIG. 29  is a schematic top view of an embodiment of a layer of a multi-layer thermoplastic crown or sole having a plurality of apertures. 
         FIG. 30  is a schematic top view of an embodiment of a layer of a multi-layer thermoplastic crown or sole having a plurality of apertures. 
         FIG. 31  is a schematic top view of an embodiment of a layer of a multi-layer thermoplastic crown or sole having a plurality of apertures and a weighted portion. 
         FIG. 32  is a schematic partial exploded view of a thermoplastic composite strike face having a plurality of unidirectional fabric reinforced composite layers and a filled or unfilled thermoplastic layer. 
         FIG. 33  is a schematic graph illustrating the coefficient of restitution and relative weight savings over titanium for a plurality of different polymers and methods of manufacturing polymeric strike faces. 
         FIG. 34  is a schematic exploded perspective view of an embodiment of a mixed material club head. 
         FIG. 35  is a schematic cross-sectional view of an embodiment of a mixed material club head, such as shown in  FIG. 34 , taken along a mid-plane of the club head. 
         FIG. 36  is a schematic perspective view of an embodiment of a thermoplastic composite front body of a golf club head with integrated weighting. 
         FIG. 37  is a schematic perspective view of an embodiment of a thermoplastic composite front body of a golf club head with integrated weighting. 
         FIG. 38  is a schematic perspective view of an embodiment of a thermoplastic composite front body of a golf club head with affixed weighting. 
         FIG. 39  is a schematic exploded perspective view of a thermoplastic composite rear body of a golf club head with weighting integrated into a forward portion of a laminate fabric reinforced composite sole member. 
         FIG. 40  is a schematic cross-sectional view of a weight member integrated between two fabric reinforced composite sheets. 
         FIG. 41  is a schematic exploded perspective view of a thermoplastic composite rear body of a golf club head with an internal weighted skeleton. 
         FIG. 42  is a schematic cross-sectional view of a thermoplastic composite rear body of a golf club head with an internal weighted skeleton, such as shown in  FIG. 41 . 
         FIG. 43  is a schematic plan view of a lower cage and a perimeter band of a weighted skeleton, such as may be used with the golf club heads in  FIG. 41 or 42 . 
         FIG. 44  is a schematic exploded perspective view of a thermoplastic composite rear body of a golf club head with a weighting member provided between laminate sheets of a fabric reinforced composite sole member. 
         FIG. 45  is a schematic top view of a fabric reinforced composite sole member with an embodiment of an integrated weighting member. 
         FIG. 46  is a schematic top view of a fabric reinforced composite sole member with an embodiment of an integrated weighting member. 
         FIG. 47  is a schematic top view of a fabric reinforced composite sole member with an embodiment of an integrated weighting member. 
         FIG. 48  is a schematic front view of a golf club head illustrating a club head center of gravity. 
         FIG. 49  is a schematic cross-sectional view of the golf club head of  FIG. 48 , taken along 49-49. 
         FIG. 50  is a plot of the center of gravity heights vs depths for various golf club head constructions. 
         FIG. 51  is a schematic top rear perspective view of an embodiment of a mixed material clubhead with a plurality of non-metallic body panels. 
         FIG. 52  is a schematic top rear perspective view of the mixed material clubhead of  FIG. 51 . 
         FIG. 53  is a schematic exploded top front perspective view of a mixed material clubhead 
         FIG. 54  is a schematic exploded top rear perspective view of the mixed material club head of  FIG. 51 . 
         FIG. 55  is a schematic partially exploded top rear perspective view of the mixed material club head of  FIG. 51 . 
         FIG. 56A  is a schematic top view of an embodiment of a non-metallic body portion for use in a mixed material golf club head. 
         FIG. 56B  is a schematic side view of an embodiment of a non-metallic body portion for use in a mixed material golf club head. 
         FIG. 57A  is a schematic top perspective view of an embodiment of a non-metallic body portion for use in a mixed material golf club head. 
         FIG. 57B  is a schematic bottom perspective view of an embodiment of a non-metallic body portion for use in a mixed material golf club head. 
         FIG. 58  is a schematic top perspective view of an embodiment of a golf club head having a polymeric crown/face component. 
         FIG. 59  is a schematic partial cross-sectional view of the golf club head of  FIG. 58 , taken along line  59 - 59 . 
         FIG. 60  is a schematic flow diagram illustrating a method of creating a multi-layered fiber reinforced composite structure for use in forming a golf club head. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides various embodiments of golf club head designs that incorporate polymeric composite structures into the overall club head construction. In some of the embodiments described below, at least a portion of the club head may be formed from a thermoplastic composite, such as, for example, a fabric reinforced thermoplastic composite or a fiber-filled thermoplastic composite. In some embodiments, one or more layers of a fabric-reinforced thermoplastic composite may be joined with one or more layers of a molded, fiber-filled thermoplastic composite. For the purpose of easily differentiating within this disclosure, a “fabric reinforced composite” is intended to refer to a composite material having a reinforcing fabric embedded within a thermoplastic matrix. The fabric may be formed from a plurality of uni- or multi-directional constituent fibers that are aligned, layered, or woven into a fabric-like pattern. Conversely, a “fiber-filled thermoplastic composite” (or “filled thermoplastic” (FT) for short) is one where discontinuous chopped fibers are mixed with a liquid/flowable polymer prior to being injected into a mold for final part creation. 
     During the molding of a filled thermoplastic, a thermoplastic resin is heated to a temperature above the melting point of the polymer, where it is freely flowable. To facilitate the flowable characteristic despite having a dispersed filler material embedded within the resin, the filler materials generally include discrete particulate having a maximum dimension of less than about 25 mm, or more commonly less than about 12 mm. For example, the filler materials may include discrete particulate having a maximum dimension of 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm, or having an average maximum dimension of between about 5 mm and about 25 mm (recognizing that breakage may occur during the molding process). Filler materials useful for the present designs may include, for example, glass beads or discontinuous reinforcing fibers formed from carbon, glass, or an aramid polymer. 
     In contrast to the discrete nature of the fibers/filler in a filled thermoplastic, the fibers in a fabric-reinforced composite (FRC) may be substantially larger/longer, and may have sufficient size and characteristics such that they may be provided as a continuous fabric separate from the polymer. When integrated with the thermoplastic resin, even if the polymer is freely flowable when melted, the included continuous fibers are generally not. 
     FRC materials are generally formed by arranging the fiber into a desired arrangement, and then impregnating the fiber material with a sufficient amount of a polymeric material to provide rigidity. In this manner, while FT materials may have a resin content of greater than about 45% by volume or more preferably greater than about 55% by volume, FRC materials desirably have a resin content of less than about 45% by volume, or more preferably less than about 35% by volume. FRC materials traditionally use two-part thermoset epoxies as the polymeric matrix, however, the present designs generally use thermoplastic polymers, instead, as the matrix. In many instances, FRC materials are pre-prepared prior to final manufacturing, and such intermediate material is often referred to as a prepreg. When a thermoset polymer is used, the prepreg is partially cured in intermediate form, and final curing occurs once the prepreg is formed into the final shape. When a thermoplastic polymer is used, the prepreg may include a cooled thermoplastic matrix that may subsequently be heated and molded into final shape. 
     As discussed below, fabric reinforced composites are best suited for portions of the design where strength is desired across a continuous surface, whereas filled thermoplastics may be best suited where more complex and/or variable geometries are desired, or at junctures where walls or features come together at angles. Likewise, each has a different dynamic response during an impact, which may further dictate placement within the design. 
     In the present designs, one or both of the front body  14  and the rear body  16  may be substantially formed from a thermoplastic composite material that includes at least one of a fabric reinforced composite or a filled thermoplastic. In some embodiments, the strike face  30  and/or front body  14  may comprise a metal (e.g. titanium alloy, steel alloy). In other embodiments, however, the strike face  30  and/or front body  14  may comprise a thermoplastic polymer and/or may be formed entirely from a thermoplastic composite material. Likewise, in some configurations, portions the rear body  16  may be comprised of a fabric-reinforced composite resilient layer and a filled thermoplastic structural layer. Furthermore, one or more portions of the rear body  16  may comprise or may be substantially formed form a metal. 
     In configurations where both the front and rear bodies  14 ,  16  include a thermoplastic composite, the front body  14  may comprise a thermoplastic composite that is the same as, or different than a thermoplastic composite of the rear body  16 . If compatible/miscible thermoplastic resins are used in both the front body  14  and rear body  16 , then in some configurations, the front body  14  may be affixed and/or coupled to at least a portion of the rear body  16  without the need for intermediate adhesives or fasteners. Instead the polymers of the adjoining bodies may be thermally fused/welded together. 
     Furthermore, in embodiments including directly abutting FRC and FT layers/portions, the use of miscible thermoplastic resins in these respective layers provides a unique ability to co-mold the layers together. This provides a club head design of unique geometries for weight savings via the filled thermoplastic layers, but also manufacturing capability of merging layers of rigid strength via the composite resilient layer. 
     Finally, in some embodiments, the use of certain thermoplastic resins may provide acoustic advantages that are not possible with other materials. Use of the thermoplastic polymers of the present construction may enable the assembled golf club head to acoustically respond closer to that of an all-metal design. 
     “A,” “an,” “the,” “at least one,” and “one or more” are used interchangeably to indicate that at least one of the item is present; a plurality of such items may be present unless the context clearly indicates otherwise. All numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; about or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range. Each value within a range and the endpoints of a range are hereby all disclosed as separate embodiment. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated items, but do not preclude the presence of other items. As used in this specification, the term “or” includes any and all combinations of one or more of the listed items. When the terms first, second, third, etc. are used to differentiate various items from each other, these designations are merely for convenience and do not limit the items. 
     The terms “loft” or “loft angle” of a golf club, as described herein, refers to the angle formed between the club face and the shaft, as measured by any suitable loft and lie machine. 
     The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus. 
     The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes with general reference to a golf club held at address on a horizontal ground plane and at predefined loft and lie angles, though are not necessarily intended to describe permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the apparatus, methods, and/or articles of manufacture described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. 
     The terms “couple,” “coupled,” “couples,” “coupling,” and the like should be broadly understood and refer to connecting two or more elements, mechanically or otherwise. Coupling (whether mechanical or otherwise) may be for any length of time, e.g., permanent or semi-permanent or only for an instant. 
     Other features and aspects will become apparent by consideration of the following detailed description and accompanying drawings. Before any embodiments of the disclosure are explained in detail, it should be understood that the disclosure is not limited in its application to the details or construction and the arrangement of components as set forth in the following description or as illustrated in the drawings. The disclosure is capable of supporting other embodiments and of being practiced or of being carried out in various ways. It should be understood that the description of specific embodiments is not intended to limit the disclosure from covering all modifications, equivalents and alternatives falling within the spirit and scope of the disclosure. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     Referring to the drawings, wherein like reference numerals are used to identify like or identical components in the various views,  FIG. 1  schematically illustrates a perspective view of a golf club head  10 . In particular, the present technology relates to the design of a wood-style head, such as a driver, fairway wood, or hybrid iron. 
     The golf club head  10  includes a front body portion  14  (“front body  14 ”) and a rear body portion  16  (“rear body  16 ”) that are secured together to define a substantially closed/hollow interior volume. As is conventional with wood-style heads, the golf club head  10  includes a crown  18  and a sole  20 , and may be generally divided into a heel portion  22 , a toe portion  24 , and a central portion  26  that is located between the heel portion  22  and toe portion  24 . 
     The front body  14  generally includes a strike face  30  intended to impact a golf ball, a frame  32  that surrounds and extends rearward from a perimeter  34  of the strike face  30  to provide the front body  14  with a cup-shaped appearance, and a hosel  36  for receiving a golf club shaft or shaft adapter. 
     To reduce the structural mass of the club head beyond what is possible with traditional metal forming techniques, some or all of the front body  14  and/or the rear body 16 may be substantially formed from one or more thermoplastic composite materials such as fabric reinforced composites and/or filled thermoplastics. The structural weight savings accomplished through these designs may be used to either reduce the entire weight of the club head  10  (which may provide faster club head speeds and/or longer hitting distances) or to increase the amount of discretionary mass that is available for placement on the club head  10  (i.e., for a constant club head weight). In a preferred embodiment, the additional discretionary mass is re-included in the final club head design via one or more metallic weights  40  (such as shown in  FIG. 2 ) that are coupled with the sole  20 , frame  32 , and/or rear-most portion of the club head  10 . 
     Referring to  FIG. 3 , in some configurations, the rear body  16  may generally be formed by bonding a crown member  50  to a sole member  52 . In a preferred embodiment, the crown member  50  forms a portion of the crown  18 , the sole member  52  forms a portion of the sole  20 , and they generally meet at an external seam that is at or slightly below where the tangent of the club head surface exists in a vertical plane (i.e., when the club head  10  is held in a neutral hitting position according to predetermined loft and lie angles). 
     With continued reference to  FIG. 3 , in an embodiment, the crown member  50  may be substantially formed from a formed fabric reinforced composite material that comprises a woven glass or carbon fiber reinforcing layer embedded in a polymeric matrix. In such an embodiment, the polymeric matrix is preferably a thermoplastic material such as, for example, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyetherimide (PEI), or a polyamide such as PA6 or PA66. In other embodiments, the crown member  50  may instead be formed from a filled thermoplastic material that comprises a glass bead or discontinuous glass, carbon, or aramid polymer fiber filler embedded throughout a thermoplastic material such as, for example, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyetherimide (PEI), or polyamide. In still other embodiments, such as described below with respect to  FIGS. 9-10 and 20-31 , the crown member 50 may have a mixed-material construction that includes both a filled thermoplastic material and a formed fiber reinforced composite material. 
     In the embodiment illustrated in  FIG. 3 , the sole member  52  has a mixed-material/multi-layer construction that includes both a fabric reinforced thermoplastic composite resilient layer  54  and a molded thermoplastic structural layer  56 . In a preferred embodiment, the molded thermoplastic structural layer 56 may be formed from a filled thermoplastic material that comprises a glass bead or discontinuous glass, carbon, or aramid polymer fiber filler embedded throughout a thermoplastic material such as, for example, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyetherimide (PEI), or a polyamide such as PA6 or PA66. The resilient layer  54  may then comprise a woven glass, carbon fiber, or aramid polymer fiber reinforcing layer embedded in a thermoplastic polymeric matrix that includes, for example, a polyphenylene sulfide (PPS), a polyether ether ketone (PEEK), polyetherimide (PEI), or a polyamide such as PA6 or PA66. In one particular embodiment, the crown member  50  and resilient layer may each comprise a woven carbon fiber fabric embedded in a polyphenylene sulfide (PPS), and the structural layer may comprise a filled polyphenylene sulfide (PPS) polymer. 
     With respect to both the polymeric construction of the crown member  50  and the sole member  52 , any filled thermoplastics or fabric reinforced thermoplastic composites should preferably incorporate one or more engineering polymers that have sufficiently high material strengths and/or strength/weight ratio properties to withstand typical use while providing a weight savings benefit to the design. Specifically, it is important for the design and materials to efficiently withstand the stresses imparted during an impact between the strike face  30  and a golf ball, while not contributing substantially to the total weight of the golf club head  10 . In general, preferred polymers may be characterized by a tensile strength at yield of greater than about 60 MPa (neat), and, when filled, may have a tensile strength at yield of greater than about 110 MPa, or more preferably greater than about 180 MPa, and even more preferably greater than about 220 MPa. In some embodiments, suitable filled thermoplastic polymers may have a tensile strength at yield of from about 60 MPa to about 350 MPa. In some embodiments, these polymers may have a density in the range of from about 1.15 to about 2.02 in either a filled or unfilled state, and may preferably have a melting temperature of greater than about 210° C. or more preferably greater than about 250° C. 
     PPS and PEEK are two exemplary thermoplastic polymers that meet the strength and weight requirements of the present design. Unlike many other polymers, however, the use of PPS or PEEK is further advantageous due to their unique acoustic properties. Specifically, in many circumstances, PPS and PEEK emit a generally metallic-sounding acoustic response when impacted. As such, by using a PPS or PEEK polymer, the present design may leverage the strength/weight benefits of the polymer, while not compromising the desirable metallic club head sound at impact. 
     With continued reference to  FIG. 3 , the illustrated design utilizes a mixed material sole construction to leverage the strength to weight ratio benefits of FRCs, while also leveraging the design flexibility and dimensional stability/consistency offered by FTs. More specifically, while FRCs are typically stronger and less dense than FTs of the same polymer, their strength is typically contingent upon a smooth and continuous geometry. Conversely, while FTs are marginally more dense than FRCs, they may form significantly more complex geometries and are generally stronger than FRCs in intricate or discontinuous designs. These differences are largely attributable to the FRCs heavy reliance on continuous fibers to provide strength, whereas FTs rely more heavily on the structure of polymer itself. 
     As such, to maximize the strength of the present design at the lowest possible structural weight, the design provided in  FIG. 3  utilizes an FRC material to form a large portion of the resilient outer shell of the sole  20 , while using an FT material to locally enhance design flexibility and/or strength. More specifically, the FT material is used to: provide optimized selective structural reinforcement (i.e., where voids/apertures would otherwise compromise the strength of an FRC); affix one or more metallic swing weights  40  (i.e., where the FT more readily facilitates the attachment of discretionary metallic swingweights by molding complex receiving cavities or over-molding aspects of the weight); and/or provide a dimensionally consistent joint structure that facilitates a structural attachment between the crown member  50  and the sole member  52  while providing a continuous club head outer surface. 
       FIG. 4  more clearly illustrates an embodiment of the sole member  52 , with an FRC resilient layer  54  bonded to a FT structural layer  56 . As shown, the structural layer  56  may generally include a forward portion  60  and a rear peripheral portion  62  that define an outer perimeter  64  of the sole member  52 . In an assembled club head  10 , the forward portion  60  is bonded to the front body  14 , and the rear peripheral portion  62  is bonded to the crown member  50 . The structural layer  52  defines a plurality of apertures  66  located interior to the perimeter  64  that each extend through the thickness of the layer  50 . Finally, the structural layer  52  may include one or more structural members  68  that extend from the forward portion  60  and between at least two of the plurality of apertures  66 . 
     As shown in  FIG. 4 , and more clearly in  FIGS. 5-7 , the resilient layer  54  may be bonded to an external surface  70  of the structural layer  56  such that it directly abuts and/or overlaps at least a portion of the forward portion  60 , the rear peripheral portion  62 , and the one or more structural members  68 . In doing so, the resilient layer  54  may entirely cover each of the plurality of apertures  66  when viewed from the exterior of the club head  10 . Likewise, the one or more structural members  68  may serve as selective reinforcement to an interior portion of the resilient layer  54 , akin to a reinforcing rib or gusset. 
     With reference to  FIGS. 2-4 , in some embodiments, the structural layer  56  may include a weighted portion  72  that is adapted to receive the one or more metallic weights  40  (e.g., tungsten-based swing weights) either by directly adhering or embedding the weight into a molded cavity, or by providing a recess  74  that is operative to receive a removable metallic mass. The weighted portion  72  is may be located toward the rear most point on the club head  10 , and therefore may be integral to and/or directly coupled with the rear peripheral portion  62  of the structural layer  56 , and spaced apart from the forward portion  60 . As noted above, the filled thermoplastic construction of the structural layer  56  is particularly suited to receive the one or more weights  40  due to its ability to form complex geometry in a structurally stable manner. More specifically, the filled thermoplastic construction of the structural layer  56  allows the design to include one or more dimensional recesses that would generally not be possible with an all-FRC construction (i.e., as the strength benefits of FRCs are typically only available across continuous surface geometries). For example, as shown in  FIG. 3 , the weighted portion  72  may be molded to define one or more weight-receiving channels or recesses that have non-uniform thicknesses, that extend around corners, and/or that join with other surfaces at sharp angles; all of which would be difficult or impossible to form strictly with a fiber reinforced composite. 
     While affixing the one or more weights  40  to the structural layer  56  at a rear portion of the club head  10  desirably shifts the center of gravity of the club head  10  rearward and lower while also increasing the club head&#39;s moment of inertia, it also may create a cantilevered point mass spaced apart from the more structural metallic front body  14 . As such, in some embodiments, the one or more structural members  68  may span between the weighted portion  72  and the forward portion  60  to provide a reinforced load path between the one or more weights  40  and the metallic front body  14 . In this manner, the one or more stiffening members  68  may be operative to aid in transferring a dynamic load between the weighted portion  72  and the front body  14  during an impact between the strike face  30  and a golf ball. At the same time, these same rib-like stiffening members  68  may be operative to reinforce the resilient layer  54  and increase the modal frequencies of the club head at impact such that the natural frequency is greater than about 3,500 Hz at impact, and exists without substantial dampening by the polymer. 
     When this surface reinforcement is combined with the desirable metallic-like acoustic impact properties of polymers such as PPS or PEEK, a user may find the club head  10  to be audibly similar from an all-metal club head while the design provides significantly improved mass properties (CG location and/or moments of inertia). 
     In a preferred embodiment, the resilient layer  54  and the structural layer  56  may be integrally bonded to each other without the use of an intermediate adhesive. Such a construction may simplify manufacturing, reduce concerns about component tolerance, and provide a superior bond between the constituent layers than could be accomplished via an adhesive or other joining methods. To accomplish the integral bond, each of the resilient layer  54  and structural layer  56  may include a compatible thermoplastic polymer that may be thermally bonded to the polymer of the mating layer. 
       FIG. 8  illustrates an embodiment of a method  80  for manufacturing a golf club head  10  having the integrally bonded resilient layer  54  and structural layer  56  of the sole member  52 . The method  80  involves thermoforming a fabric reinforced thermoplastic composite into an external shell portion of the club head  10  at step  82 . The thermoforming process may involve, for example, pre-heating a thermoplastic prepreg to a molding temperature at least above the glass transition temperature of the thermoplastic polymer, molding the prepreg into the shape of the shell portion, and then trimming the molded part to size. 
     Once the composite shell portion is in a proper shape, a filled thermoplastic supporting structure may then be injection molded into direct contact with the shell at step  84 . Such a process is generally referred to as insert-molding. In this process, the shell is directly placed within a heated mold having a gated cavity exposed to a portion of the shell. Molten polymer is forcibly injected into the cavity, and thereafter either directly mixes with molten polymer of the heated composite shell, or locally bonds with the softened shell. As the mold is cooled, the polymer of the composite shell and supporting structure harden together in a fused relationship. The bonding is enhanced if the polymer of the shell portion and the polymer of the supporting structure are compatible, and is even further enhanced if the two components include a common or otherwise miscible thermoplastic resin component. While insert-molding is a preferred technique for forming the structure, other molding techniques, such as compression molding, may also be used. 
     With continued reference to  FIG. 8 , once the sole member  52  is formed through steps  82  and  84 , an FRC crown member  50  may be bonded to the sole member  52  to substantially complete the structure of the rear body  16  (step  86 ). In a preferred embodiment, the crown member  50  may be formed from a thermoplastic FRC material that is formed into shape using a similar thermoforming technique as described with respect to step  82 . Forming the crown member  50  from a thermoplastic composite allows the crown member  50  to be bonded to the sole member  52  using a localized welding technique. Such welding techniques may include, for example, laser welding, ultrasonic welding, or potentially electrical resistance welding if the polymers are electrically conductive. If the crown member  50  is instead formed using a thermoset polymer, then the crown member  50  may be bonded to the sole member  52  using, for example, an adhesive or a mechanical affixment technique (studs, screws, posts, mechanical interference engagement, etc). 
       FIG. 6  generally illustrates an embodiment of a joint  90  that is operative to couple the crown member  50  and sole member  52 . As shown, the structural layer  56  separately receives the resilient layer  54  and crown member  50  to form a continuous external surface  92  (i.e., the external surface  92  of the rear body  16  comprises an external surface  94  of the crown member  50 , an external surface  70  of the structural layer  56 , and an external surface  96  of the resilient layer  54 ). 
     Referring again to  FIG. 8 , the rear body  16 , comprising the affixed crown member  50  and sole member  52  may subsequently be affixed to the front body structure  14  at step  88 . In an embodiment where both the frame  32  of the front body  14  and the forward portion of the rear body  16  comprise a common or otherwise miscible thermoplastic, the affixment step  88  may be performed via thermal fusing and without the use of intermediate adhesives. If the front body  14  is substantially formed from a metal, the affixment may require the use of adhesives to facilitate the bond. While adhesives readily bond to most metals, the process of adhering to the polymer may require the use of one or more adhesion promoters or surface treatments to enhance bonding between the adhesive and the polymer of the rear body  16 . 
       FIG. 7  schematically illustrates an example of a bond interface  100  between the sole member  52  and a metallic embodiment of the frame  32  of the front body  14 . As shown, the bond interface  100  resembles a lap joint where the structural layer  56  and/or resilient layer  54  overlay a bonding flange  102  that is inwardly recessed from an external surface  104  of the frame  32 . In the illustrated embodiment, the structural layer  56  may be adhesively bonded directly to the bonding flange  102  via an intermediately disposed adhesive  106 . Furthermore, the resilient layer  54  may extend over the entire forward portion  60  of the structural layer  56  such that the external surface  96  of the resilient layer  54  is flush with the external surface  104  of the frame  32 . By recessing the bonding flange  102  in the manner shown, the structural layer  56  and/or resilient layer  54  may directly abut an extension wall  108  joining the frame  32  and flange  102  to further facilitate the transfer of dynamic impact loads from the weight  40 /weighted portion  72  to the frame  32 . 
     In some embodiments, the resilient layer  54  may have a substantially uniform thickness that may be in the range of from about 0.5 mm to about 0.7 mm, from about 0.5 mm to about 1.0 mm, or from about 0.6 mm to about 0.9 mm, or from about 0.7 mm to about 0.8 mm. In some embodiments, the resilient layer  54  may have a substantially uniform thickness of 0.5 mm, 0.55 mm, 0.60 mm, 0.65 mm, or 0.70 mm. In areas of the structural layer  56  that directly abut the resilient layer  54  (i.e., areas where the resilient layer  54  is located exterior to the structural layer  56 ), some embodiments of the structural layer  56  may have a substantially uniform thickness of from about 0.5 mm to about 0.7 mm, from about 0.5 mm to about 1.0 mm, or from about 0.6 mm to about 0.9 mm, or from about 0.7 mm to about 0.8 mm. In some embodiments, the structural layer  56  may have a substantially uniform thickness of 0.5 mm, 0.55 mm, 0.60 mm, 0.65 mm, or 0.70 mm. A substantially uniform construction of both the resilient layer  54  and the structural layer  56  is generally illustrated in  FIGS. 4-7 and 11 . In these embodiments, the total thickness of the resilient layer  54  and the structural layer  56  may be, for example, in the range of from about 1.0 mm to about 1.5 mm, from about 1.0 mm to about 2.0 mm, or from about 1.25 mm to about 1.75 mm, or from about 1.4 mm to about 1.6 mm. In some embodiments, the total thickness of the resilient layer  54  and the structural layer  56  may be 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm. 
     Referring again to  FIGS. 3 and 6 , in an embodiment, the recessed bonding flange  102  may entirely encircle the strike face  30  and/or extend from the frame  32  across all portions of the crown  18  and sole  20 . In this manner, as shown in  FIG. 6 , the rear body  16  may further be affixed to the front body  14  by adhering the crown member  50  to the bonding flange  102 . 
     While the method  80  illustrated in  FIG. 8  is primarily focused with forming a club head similar to that shown in  FIG. 3  (i.e., where step  82  forms the resilient layer  54  of the sole member  52  and step  84  forms the structural layer  56  of the sole member  52 ), the processes described with respect to steps  82  and  84  may also (or alternatively) be used to form a crown member  50 . For example, as shown in  FIGS. 9 and 10 , the crown member  50  may include one or both of an outer structural layer  110  and an inner structural layer  112  bonded to a thermoplastic FRC resilient crown layer  114 . While the inner structural layer  112  may generally function in a similar manner as the structural layer  56  of the sole member  52 , the outer structural layer  110  may provide further weight saving benefits by concentrating reinforcing structure in areas where it provides the most structural benefit while also enabling thinner component thicknesses at interstitial spaces. In general, the present concept of structural ribbing generally results in the creation of weight reduction zones between the ribbing. These weight reduction zones may be in the sole or the crown, and are further described in U.S. Pat. Nos. 7,361,100 and 7,686,708, which are incorporated by reference in its entirety. 
     Specific to construction of a mixed-material crown member  50 , and similar to that described above with respect to the sole member  52 , the formation may begin by thermoforming a fiber reinforced thermoplastic composite into an external shell portion of the club head  10 . The thermoforming process may involve, for example, pre-heating a thermoplastic prepreg to a molding temperature at least above the glass transition temperature of the thermoplastic polymer, molding the prepreg into the shape of the shell portion, and then trimming the molded part to size. 
     Once the composite shell portion is in a proper shape, a filled thermoplasticic supporting structure (i.e., one or both of the inner structural layer  112  and outer structural layer  114 ) may then be injection molded into direct contact with the shell (e.g., via insert-molding, as described above). 
     While  FIGS. 4-10  generally focus on construction of the rear body  16 , these same co-molding techniques may be employed to form a thermoplastic composite front body  14 , such as generally illustrated in  FIGS. 11-13 . More specifically,  FIG. 12  illustrates a first front body configuration  200  that includes a filled thermoplastic outer layer  202  coupled to the outer surface  204  of a fabric reinforced composite layer  206 . In this embodiment, the filled thermoplastic outer layer  202  defines the ball-striking surface while the fabric reinforced composite layer  206  provides a high strength backing to the face  30 . In some embodiments, the fabric reinforced composite layer and filled thermoplastic layer may each extend across the entire strike face to provide resiliency and strength to withstand repeated high speed impacts with a golf ball. Additionally, in some embodiments, the fabric reinforced composite layer  206  may sweep rearward to form at least a portion of the frame  32 . As shown, in one embodiment, the fabric reinforced composite layer  206  may have a generally uniform thickness  208  that is formed from one or more layers of a uni- and/or multi-directional ply extending continuously across a substantial majority of the strike face  30 . 
     As further shown, the filled thermoplastic outer layer  202  may have a variable thickness  210  that extends between the fabric reinforced composite layer  206  and the ball striking surface. In embodiments where the fabric reinforced composite layer  206  has a substantially uniform thickness, the filled thermoplastic outer layer  202  may primarily contribute to a variable thickness  212  of the strike face  30  as a whole. 
       FIG. 13  then provides a second front body configuration  220  that includes a filled thermoplastic inner layer  222  coupled to the inner surface  224  of a fabric reinforced composite layer  226 . In this embodiment, the fabric reinforced composite layer  226  defines the strike face  30  and extends rearward to form at least a portion of the frame  32 . The filled thermoplastic inner layer  212  then serves as a structural backing to the composite layer  226 . Similar to  FIG. 12 , in an embodiment, the fabric reinforced composite layer  226  may generally have a uniform thickness  228  that is formed from one or more layers of a uni- and/or multi-directional ply extending continuously across a substantial majority of the strike face  30 . The filled thermoplastic inner layer  222  may then have a variable thickness  230  that may be designed to tune the dynamic response of the face  30  to an impact. 
     As shown in  FIGS. 12-13 , each front body configuration  200 ,  220  may include a variable face thickness that is substantially provided for by the filled thermoplastic layer  202 ,  222 . In many embodiments, the face thickness may vary such that the minimum face thickness ranges from 0.114 inch and 0.179 inch, and the maximum face thickness ranges from 0.160 inch to 0.301 inch. The minimum face thicknesses may be 0.110 inches, 0.114 inches, 0.115 inches, 0.120 inches, 0.125 inches, 0.130 inches, 0.135 inches, 0.140 inches, 0.145 inches, 0.150 inches, 0.155 inches, 0.160 inches, 0.165 inches, 0.170 inches, 0.175 inches, 0.179 inches, or 0.180 inches. The maximum face thickness may be 0.160 inches, 0.165 inches, 0.170 inches, 0.175 inches, 0.180 inches, 0.185 inches, 0.190 inches, 0.195 inches, 0.200 inches, 0.205 inches, 0.210 inches, 0.215 inches, 0.220 inches, 0.225 inches, 0.230 inches, 0.235 inches, 0.240 inches, 0.245 inches, 0.250 inches, 0.255 inches, 0.260 inches, 0.265 inches, 0.270 inches, 0.275 inches, 0.280 inches, 0.285 inches, 0.290 inches, 0.300 inches, 0.301 inches, 0.305 inches, or 0.310 inches. 
     With reference to  FIG. 14 , in some embodiments, a filled thermoplastic inner layer  222  may include one or more discontinuities, voids, debossed geometries, or other irregular surface geometries. In some configurations, the fabric reinforced composite layer  226  may be visible through one or more molded-in holes or channels in the filled thermoplastic inner layer  222 . In the embodiment shown in  FIG. 14 , the filled thermoplastic inner layer  222  may define a channel  232  extending around a perimeter of the strike face  30  to increase face bending and increase energy transfer to a golf ball during impact. The illustrated embodiment of  FIG. 14  illustrates the channel  232  extending continuously around the perimeter of the strike face  30 . However, in other embodiments, the channel  232  may extend discontinuously around one or more portions of the perimeter of the strike face  30 . Further, in other embodiments, the channel  232  may extend along any portion of the back side of the strike face  30 . 
     In the illustrated embodiment of  FIG. 14 , the channel  232  comprises a rounded concave cross sectional geometry. In other embodiments, the channel  232  may comprise any cross sectional geometry, including but not limited to circular, elliptical, square, rectangular, triangular, or any other polygon or shape with at least one curved surface. Further, the channel  232  comprises a depth, measured as the maximum depth of the channel  232  in a direction extending substantially perpendicular to the back side of the strike face  30 . In many embodiments, the depth of the channel may range from about 0.1 mm about 3 mm. in another embodiment, the depth of the channel may range from about 0.125 mm to about 2 mm. 
     In the illustrated embodiment, the channel  232  allows the strike face  30  to absorb 0.9% more impact energy that is transferrable to a golf ball to increase ball speed and travel distance. In many embodiments, the channel  232  allows the strike face  30  to absorb 0.75% to 1.5% more impact energy that may be transferred to a golf ball to increase ball speed and travel distance. 
     In an embodiment where a filled thermoplastic outer layer  202  is disposed outward of a fabric reinforced composite layer  206 , such as shown in  FIG. 11 , the filled thermoplastic material may form one or more aerodynamic features that may operatively reduce club head drag and increase the speed of the club. Such features may include a repeating pattern of debossed geometric shapes (e.g., hemispherical depressions, hexagonal depressions, pyramidal depressions, grooves, or the like), a repeating pattern of embossed geometric shapes (e.g., hemispherical protrusions, hexagonal protrusions, pyramidal protrusions, ribs, or the like). Likewise, these aerodynamic features may include discrete depressions or protrusions such as the plurality of turbulators  240  illustrated in  FIG. 11 . These aerodynamic features may be used to alter boundary layer air flow and are described further in U.S. Pat. No. 9,555,294 (the &#39;294 Patent), which is incorporated by reference in its entirety. As may be appreciated, the molded thermoplastic material may be particularly suited for creating these aerodynamic features (i.e., when compared with a fabric reinforced composite) due to the nature of polymeric molding where the surface profile of the mold dictates the surface geometry of the finished part. 
     Because filled thermoplastics may have anisotropic structural qualities that are dependent on the typical or average orientation of the embedded, discontinuous fibers, special attention may need to be paid to the formation of the filled thermoplastic (FT) layer  202 ,  222  to ensure that it has sufficient strength to withstand repeated impacts. More specifically, a filled polymeric component will generally have greater strength against loads that are aligned with the longitudinal axis of the embedded fibers, and comparatively less strength to loads applied laterally. Because fiber orientation within a filled polymer is highly dependent on mold flow during the initial part formation, embodiments of a polymeric front body  14  may utilize mold and part designs that aid in orienting the embedded fiber along the most likely force/stress propagation paths. 
     As is understood, during a molding process, such as injection molding, embedded fibers tend to align with a direction of the flowing polymer. With some fibers (i.e., particularly with short fiber reinforced thermoplastics) and resins, the alignment tends to occur more completely close to the walls of the mold or edge of the part. These layers are referred to as shear layers or skin layers. Conversely, within a central core layer, the fibers may sometimes be more randomized and/or perpendicular to the flowing polymer. The thickness of the core layer may generally be altered by various molding parameters including molding speed (i.e., slower molding speed may yield a thinner core layer) and mold design. With the present designs, it is desirable to minimize the thickness of any randomized core layer to enable better control over fiber orientation. 
     During an impact, stresses tend to radiate outward from the impact location while propagating toward the rear of the club head  10 . Additionally, bending moments are imparted about the shaft, which induces material stresses between the impact location and the hosel  36 , and along the hosel  36 /parallel to a hosel axis  240  (as shown in  FIG. 15 ). Therefore, where applicable, it is preferable for the embedded fibers to generally follow these same directions; namely: within the hosel  36  parallel to the hosel axis  240 ; across at least the center of the face  30  (represented by the horizontal face axis  242 ); and, generally outward from the face center with the fibers turning largely rearward within the frame  32  (i.e., parallel to a fore-rear axis  244 ). 
     Because the discontinuous fibers are mixed within the flowable polymer prior to forming the part, it is impossible to guarantee perfect alignment. With that said, however, the design of the front body  14  and manner of injection molding (e.g., fill rate, gating/venting, and temperature) may be controlled to align as many of the embedded fibers with these axes as possible. For example, within the hosel, it is preferable if greater than about 50% of the fibers are aligned within 30 degrees of the hosel axis  240 . Between the center of the face and the hosel  36 , it is preferable if greater than about 50% of the fibers are aligned within 30 degrees of the horizontal face axis  242 , and/or within the frame  32 , it is preferable if greater than about 50% of the fibers are aligned within 30 degrees of the fore-rear axis  244 . In another embodiment, greater than about 60% of the fibers within the hosel  36  are aligned within 25 degrees of the hosel axis  240 , greater than about 60% of the fibers between the center of the face and the hosel  36  are aligned within 25 degrees of the horizontal face axis  242 , and/or greater than about 60% of the fibers within the frame  32  are aligned within 25 degrees of the fore-rear axis  244 . In still another embodiment, greater than about 70% of the fibers within the hosel  36  are aligned within 20 degrees of the hosel axis  240 , greater than about 70% of the fibers between the center of the face and the hosel  36  are aligned within 20 degrees of the horizontal face axis  242 , and/or greater than about 70% of the fibers within the frame  32  are aligned within 20 degrees of the fore-rear axis  244 . 
       FIGS. 16-17  illustrate an FT layer  202 ,  222  that generally accomplishes the fiber alignment described above. In these figures, the FRC layer  206 ,  226  is removed to better show the contours of the face  30 . While  FIGS. 16-17  illustrate the FT layer  202 ,  222  forming at least a portion of the frame  32 , it should be noted that this layer need not form or complete the frame  32 , and in some embodiments, the FT layer  202 ,  222  is constrained solely to the strike face  30  while the FRC layer  206 ,  226  forms the entirety of the frame  32 . 
       FIG. 16  schematically illustrates the flow and fiber alignment within one embodiment of the FT layer  202 ,  222 . As shown through these figures, flowable polymer passes from a sprue  250  and connected gate  252  directly into the toe portion  24  of the front body  14 . From there, the polymer may flow across the face  30 , and then upward through the hosel  36 . By flowing across the face  30  and upward through the hosel  36 , the FT may form the somewhat complex geometries of the hosel  36 , while pushing weld lines high and to the heel side of the hosel  36 , which is generally the lowest stress area of the hosel  36 . If the front body  14  were attempted to be gated at the hosel  36  (instead of at the toe), there is a greater likelihood of introducing a weld line in or near the face  30 , or on the toe side of the hosel  36 , which experiences comparatively greater stress than the heel side. Because weld lines have a lower ultimate strength than the typical polymer, it is important to ensure that they do not get formed in areas that typically experience higher stresses. 
     To encourage the polymer to fill the hosel  36  from bottom to top, it may be desirable to fill the face from a location near the toe  24  and that is at or preferably above the horizontal centerline  254  of the face  30  (i.e., between the crown  18  and a line drawn through the center of the face  256  and parallel to a ground plane when the club is held at address). This may encourage the flow  258  and corresponding fiber alignment to follow a generally downward slant from above the horizontal centerline  254  at the toe  24  toward the center of the face  256  while between the toe and the center  256 . Following this, at the center  256 , the flow  260  and corresponding fiber alignment may generally be parallel to the horizontal centerline  254  at or immediately surrounding the center of the face  256 . Finally, the flow  262  may arc upward and fill the hosel  36  largely from the bottom toward the neck. While  FIG. 16  illustrates the gate  252  directly attaching to the frame  32 , in the absence of an FT frame, the gate  252  may directly couple with a portion of the strike face  30  closest to the toe  24 . The general directional references illustrated at  258 ,  260 , and  262  are generally intended to indicate that greater than about 50% of the fibers within the polymer are aligned within about 30 degrees of the indicated direction, or more preferably that more than about 60% of the fibers are aligned within about 25 degrees of the indicated direction, or even more preferably that more than about 70% of the fibers are aligned within about 20 degrees of the indicated direction. 
     As shown in  FIG. 17-18 , to promote the directional flow  258 ,  260  across the face  30  while also encouraging a slight downward arc at  258 , a flow leader  264  may protrude from a rear surface  266  of the FT layer  202 ,  222 . As shown, the flow leader  264  may be an embossed channel that extends from an edge of the FT layer  202 ,  222  at or near the gate and propagates away from the gate, inward toward a central region of the face  30 . It may serve as a path of comparatively lower resistance for material to flow during molding, thus ensuring a primary flow-direction. In some embodiments, the flow leader  264  may be raised above the surrounding surface  266  by a height of from about 0.5 mm to about 1.5 mm, or from about 0.7 mm to about 1.0 mm. Furthermore, the flow leader  264  may have a lateral width, measured orthogonally to the height and to a line from the origin of the flow leader at the toe  24  to the face center  256 , of from about 5 mm to about 15 mm, or from about 7 mm to about 12 mm. 
     As further shown in  FIGS. 17-18 , in one embodiment, the flow leader  264  may lead into a thickened central region  268  of the face  30 . This thickened central portion  268  may primarily be used to stiffen the central region of the face against impacts so that the face moves more as a single unit while avoiding local deformations. From a molding perspective, this thickened region  268  may serve as a well or manifold of sorts that may supply polymer radially outward to fill the frame from front to back (or at least to steer polymer flowing through the thinner areas toward the rear edge  270  of the frame). The flow convergence from the thicker region  268  to the surrounding thinner areas will also aid aligning the embedded fibers.  FIG. 18  further illustrates a FRC backing  206  provided on an internal surface of the front body  14 , similar to  FIGS. 11-12 . 
     While  FIGS. 16-18  specifically illustrate fiber alignment in the front body  14  and strike face  30 , these techniques should be regarded as illustrative and equally applicable to the rear body  16 . For example, in some embodiments, any injection molded structure of the rear body (e.g., the structural layer  56  shown in  FIG. 3 ) may be gated/molded to align embedded, discontinuous fibers along primary load path axes, while minimizing knit lines or pushing knit lines to locations that experience comparatively lower stress. To accomplish this, for example, in one embodiment, the rear body  16  may be gated at the rear most point of the structural layer  56  such that fiber containing resin flows uniformly from back to front. The structure may likewise be optimized to promote a uniform flow front, such as by minimizing the amount of structure that may divert resin flow or prevent the flow from continuing forward. In other embodiments, the structure may include one or more flow leaders that are operative to channel resin in a back to front manner. In both the front body  14  and rear body  16 , it is preferable to utilize only one gate, as the flow coming from multiple gates will eventually converge and form structurally unsound knit lines. 
       FIG. 19  illustrates an embodiment of a method  280  of manufacturing a front body  14  having an integrally bonded FRC resilient layer  206 ,  226  and an FT structural layer  202 ,  222 . The method  280  generally begins by thermoforming a fabric-reinforced thermoplastic composite into a shell portion of the front body  14  at step  282 . The thermoforming process may involve, for example, pre-heating one or more thermoplastic prepregs to a molding temperature at least above the glass transition temperature of the thermoplastic polymer, molding the prepreg into a desired shape, and then trimming the molded part to size. In one configuration, the one or more prepregs are compression molded into a shape that may form the outer surface of the strike face  30  and frame  32 , such as shown in  FIG. 13 . Such a configuration may generally entail a final shape with a plurality of flat and/or rounded surfaces. In another configuration, the one or more prepregs are compression molded into a shape that may form at least a portion of the inner surface of the front body  14  or strike face  30 . In such an embodiment, the compression molded prepreg may follow the outer contours of any variable face thickness, flow leaders, or other internal surface features to direct the flow of material. In doing so, the outer surface  204  may create surface depressions that will eventually be filled by a flowable polymer. 
     Once the composite shell portion is in a proper shape, it is placed within a mold at  284 , after which a filled thermoplastic is then injection molded into direct contact with the FRC at step  286 . As previously mentioned, such a process is generally referred to as insert-molding. In this process, the pre-formed shell is directly placed within a heated mold having a gated cavity/void that is directly abuts an exposed portion of the shell. Molten polymer is forcibly injected into the cavity, and thereafter it either directly mixes with molten polymer of the heated composite shell, or locally bonds with the softened shell. As the mold is cooled, the polymer of the composite shell and supporting structure harden together in a fused relationship. The bonding is enhanced if the polymer of the shell portion and the polymer of the supporting structure are compatible, and is even further enhanced if the two components include a common or otherwise miscible thermoplastic resin component. While insert-molding is a preferred technique for forming the structure, other molding techniques, such as compression molding, may also be used (e.g., where the FT layer is produced as a distinct, independent layer, and then fused with other layers via compression molding) 
     In further designs, a plurality of inserts are provided into the mold prior to injecting the filled thermoplastic. For example, a first insert may form the outer surface of the front body  14 , a second insert may then form a reinforced back surface, and the filled thermoplastic may be injected in between. In another embodiment, one or more reinforcing meshes, including metallic meshes or screens, may be embedded within the FT layer to provide additional reinforcement and strength. In such an embodiment, to facilitate solid integration between the mesh and the FT layer, the mesh may include a plurality of apertures within which the thermoplastic resin may flow during creation of the FT layer. 
     While the disclosure above generally explains the use of thermoplastic composites that have at least one fabric-reinforced composite layer and at least one filled thermoplastic layer, it should be understood that the present techniques are not limited to simply two layers in a given component. In many embodiments, the thermoplastic composites may comprise a laminate that has two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more layers of mixed material. By forming each layer with a thermoplastic base resin, there is almost no limit to the number of times that any one or more layers may be reformed if the design so requires. This very nature may then enable the creation of intricate and/or complex three-dimensional material structures by pre-forming layers with different grain patterns, internal fiber orientations, and/or aperture size, shape, and/or spacing. This technology then enables the strength to weight ratio to be optimized by engineering the structure of the material, itself. 
     In some embodiments, one or more of the strike face  30 , crown  18 , or sole  20  may comprise a plurality of distinct layers of thermoplastic composite, each fused to at least one directly adjacent/abutting thermoplastic composite layer without the use of an intermediate adhesive. Each layer may consist of a fabric reinforced thermoplastic composite, a filled thermoplastic (preferably filled with a long and/or short fiber fill), or an unfilled thermoplastic. The base thermoplastic resin of each layer may be identical or otherwise miscible with the base thermoplastic resin of one or more of the directly abutting layers. In this manner, in one configuration, at least a plurality of the layers may be separately formed and then collectively fused together through the application of heat and pressure, such as with a compression molding process. 
       FIG. 20  illustrates an example of such a laminate construction as may be used with a crown  18  (though such a design may likewise be capable of being used in a sole). As shown via the exploded view  300 , the crown  18  comprises three layers, with a first layer  302  forming a portion of the outer surface  304 , a second layer  306  forming a portion of the inner surface  308 , and a third layer  310  disposed between the first and the second layers  302 ,  306 . In this embodiment, the first layer  302  is solid throughout and comprises no apertures. The second layer  306  comprises a first plurality of hexagonal-shaped apertures  312  spanning a majority of the crown  18 . The third layer  310  comprises a second plurality of hexagonal-shape apertures  314  spanning a majority of the crown  18 , though offset from the positioning of the first plurality of hexagonal-shaped apertures  312  when the layers are nested together, such as shown in  FIG. 21 . One or both of the second layer  306  and third layer  310  may comprise a filled thermoplastic. Likewise, one or both of the second layer  306  and the third layer  310  may comprise a fabric reinforced composite. If an FRC is employed, it is preferable for each of the reinforcing fibers to extend around the apertures  312 ,  314  rather that terminating at the aperture as if the apertures were cut into a pre-formed sheet. Further explaining the benefits of thermoplastics, each layer shown in  FIG. 20  may be individually formed and fully hardened in a dimensionally stable manner before stacking within a compression mold that essentially welds the layers together across the entire surface by heating each layer to a temperature above its respective glass transition temperature. Doing so may enable complex  3 D material structures to be engineered by forming and reforming each layer individually and/or collectively multiple times. 
     Further expanding on the concept of engineered material structures,  FIGS. 22 and 23  illustrate an embodiment similar to that shown in  FIGS. 20-21 , though the designs of the different layers are made to serve different specific purposes. As shown,  FIG. 22  illustrates an exploded (or pre-assembled) view of a crown member  320  that includes a first, outer layer  322 , a second, middle layer  324 , and a third, bottom layer  326 . The first layer  322  is substantially solid, such as in the design of  FIG. 20 . The second layer  324  includes a plurality of struts  328  that extend between a forward portion  330  of the crown member, and a rear portion  332  of the crown member  320 . These struts  328  are operative to stiffen the crown in a front-rear dimension. The third layer  326  then includes at least one strut  334  that extends laterally across the crown member  320  to stiffen the crown in a heel-toe direction. 
     While  FIG. 22  demonstrates one embodiment of using the individual layer structures to achieve different structural design objectives, in some embodiments, the layers may be used to strategically alter weight performance as well. For example, different layers may have different densities (e.g., through the use of different density fillers or fabric reinforcements), and may be included solely to affect the location of the center of gravity or the moment of inertia. To this effect, each layer may have a different layer-specific center of gravity that is located in a different location within the layer than other layer-specific centers of gravity. Likewise, some layers may serve as “structural layers” and may provide an optimized structural design, while other layers may serve as “mass layers” that may be used to alter the placement of the center of gravity of the club head. In some embodiments, the mass layers may be doped with a metallic filler such as tungsten. Mass layers may be particularly suited for use in the sole, where additional mass may serve the functional purpose of moving the center of gravity of the club head rearward and down. An example of the structure of a mass layer may include a layer where apertures are concentrated in the forward portion of the layer, while the rear portion is devoid of apertures. 
       FIGS. 24-31  each illustrate different lamina layer design embodiments that may have functional characteristics and that may be used alone or in combination with other ones of the illustrated designs or solid layers to form a crown  18  or sole  20 . If solid layers are used, they may comprise fabric reinforced composites, filled thermoplastics, or unfilled thermoplastics. In some embodiments, the laminate may comprise a plurality of unidirectional fabric reinforced composite layers, each provided at a different relative orientation (i.e., where the longitudinal axis of the fibers are rotated relative to abutting layers when viewed from a plan view). 
       FIG. 24  provides one embodiment of a fiber reinforced laminate layer  350  that may be used in the formation of a portion of the crown  18  or sole  20 . As shown, the layer  350  may comprise a plurality of apertures  352 , wherein the apertures  352  each have a circular shape. The apertures  352  may be positioned throughout the entire surface of the layer  350 . Such apertures  352  may be similar to those described in U.S. Pat. 9,776,052, which is incorporated by reference in its entirety. 
       FIG. 25  is another embodiment of a fiber reinforced laminate layer  360  that may be used in the formation of a portion of the crown  18  or sole  20 . As shown, the layer  360  may comprise a plurality of apertures  362 , including four apertures  362  extending from near the strikeface  30  toward the trailing edge  364 . The apertures include a first aperture positioned near the heel end  366 , a second aperture positioned near the toe end  368 , a third aperture positioned between the first and second apertures, and a fourth aperture positioned between the third aperture and the second aperture, wherein the first and second aperture comprise a triangular shape, while the third and fourth aperture comprise a trapezoidal shape. 
       FIG. 26  is another embodiment of a fiber reinforced laminate layer  370  that may be used in the formation of a portion of the crown  18  or sole  20 . As shown, the layer  370  may comprise a plurality of apertures  372  that includes a first, second, third and fourth aperture near the strikeface  30 , positioned in a heel-toe direction, a fifth, sixth, seventh, and eighth aperture near the trailing edge  374 , positioned in a heel-toe direction, and a ninth and tenth aperture centered, positioned in between the first through eighth apertures. 
       FIG. 27  is another embodiment of a fiber reinforced laminate layer  380  that may be used in the formation of a portion of the crown  18  or sole  20 . As shown, the layer  380  may comprise a plurality of apertures  382  that includes four apertures  382  extending from near the strikeface  30  toward the trailing edge  384 , having a first aperture positioned near the heel end  386 , a second aperture positioned near the toe end  388 , a third aperture positioned between the first and second apertures, and a fourth aperture positioned between the third aperture and the second aperture, wherein the material between the first, second, third, and fourth apertures comprise a circular shape such that the first, second, third and fourth apertures comprise a skewed polygonal shape. In some embodiments, these circular portions may be used to alter one or more mass properties of the layer and/or the club head in general. 
       FIG. 28  illustrates another embodiment a fiber reinforced laminate layer  390  that may be used in the formation of a portion of the crown  18  or sole  20 . As shown, the layer  390  may comprise an aperture  392  having a plurality of material portions  394  extending from the perimeter  396  of the layer  390  toward the center. In material portion  394  may include an enlarged mass portion  3986  at the distal end of the material portion  394  for the purpose of altering one or more mass properties of the layer  390  and/or the club head in general. 
       FIG. 29  is another embodiment of a fiber reinforced laminate layer  400  that may be used in the formation of a portion of the crown  18  or sole  20 . As shown, the layer  400  may comprise a plurality of apertures  402  that includes six apertures, with a first aperture closest to the strike face, and each consecutive aperture (i.e., second, third, fourth, fifth and sixth aperture) are positioned adjacent to one another in a direction toward the rear of the golf club head  10 . Each aperture  402  comprises an arc like stripe shape, extending from a heel end  404  to the to end  406  in a arcuate manner. 
       FIG. 30  is another embodiment of a fiber reinforced laminate layer  410  that may be used in the formation of a portion of the crown  18  or sole  20 . As shown, the layer  410  may comprise a plurality of apertures  412  that includes three apertures, with a first aperture positioned near the strike face on a toe end  404 , a second aperture positioned near the strikeface on a heel end  406 , and a third aperture positioned near the rear  408 , in between the heel and toe ends  406 ,  404 . The material partitioning the three apertures then may form a Y-shape. 
       FIG. 31  then illustrates an embodiment similar to that in  FIG. 30 , though with the inclusion of a mass portion  420  in the center of the layer (at the intersection of each arm of the “Y-shape.” In this manner, mass portions may be included with any of the example layers shown in  FIGS. 24-30 , and such mass portions are not limited to only circular portions, but rather may take any shape. 
     In a similar manner as illustrated with the crown/sole in  FIGS. 20-31 , the strike face  30  may comprise a plurality of lamina layers, where at least two of the layers are integrally fused through a compression molding operation. In one configuration, such as shown in  FIG. 32 , the strike face  30  may comprise a plurality of unidirectional fabric reinforced thermoplastic composite layers  450 , with each layer being rotated relative to adjacent layers. Each layer may include a common base thermoplastic resin that, when collectively heated above the glass transition temperature of the polymer, will fuse with the polymer of the abutting layers. In some embodiments, the strike face  30  may further include a filled or unfilled thermoplastic layer  452  that may be pre-formed and compression molded together with the FRC layers  450 , or may be injection molded into contact with the fused FRC layers, for example, through an insert injection molding process. Forming such a layup/laminate with thermoplastics used as the resin matrix has proven to provide a more repeatable layup while providing desirable weight savings and coefficients of restitution. Three examples of stacking sequences that have proven to have suitable strength properties are illustrated in Table 1, below: 
     
       
         
           
               
               
               
             
               
                   
               
               
                   
                 Nominal 
                   
               
               
                   
                 Thickness of 
               
               
                 Layers 
                 Laminate 
                 Stacking Sequence 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 8 
                 0.048 
                 0/90/45/−45/−45/45/90/0 
               
               
                 16 
                 0.096 
                 0/90/45/−45/−45/45/90/0/0/90/45/−45/−45/ 
               
               
                   
                   
                 45/90/0 
               
               
                 24 
                 0.144 
                 0/90/45/−45/−45/45/90/0/0/90/45/−45/−45/ 
               
               
                   
                   
                 45/90/0/0/90/45/−45/−45/45/90/0 
               
               
                   
               
            
           
         
       
     
       FIG. 33  illustrates how different injection molded composites perform both in terms of relative coefficient of restitution (COR)  460  and in terms of relative weight savings  462  when compared with a titanium metal face. As can be seen, compression molded fabric reinforced composites  464  tend to be lighter and may have a greater COR than neat injection molded variants  466  of similar polymers. Due to the lower percentage of resin in the compression molded layers, however, the compression molded composites, however, tend to be comparatively more brittle than the illustrated injection molded variants. As such, in some design embodiments, a combination of the two may ultimately provide the most desirable results with the best balance of strength and resiliency. 
     As mentioned above, different mixed materials or compounds/elements may form each of these lamina layers within the crown  18 , sole  20 , and/or strike face  30 . The different lamina layers may share a common matrix polymer (i.e., the same thermoplastic polymer in each lamina layer), and either the same or different reinforcement elements or compounds per lamina layer. The different lamina layers may share a common derivative matrix polymer that is not chemically the same, but is miscible to each other. For example, one lamina layer could be a thermoplastic polymer that is one chemical compound, and he next lamina layer is another thermoplastic compound that is a different chemical formula from the thermoplastic compound of the lamina layer above, but shares enough chemical structure, 3D shape, and chemical properties to be miscible with the thermoplastic layer above. Each of the reinforcement element or compound can be the same or different in these “miscible” thermoplastic lamina layers. The different lamina layer may also share a thermoplastic resin that is common with each layer, but each lamina layer may have the same or different matrix polymer and/or reinforcement element/compound. 
     The combination of the matrix polymer and reinforcement element (fabric or fiber fill) allows for the end product to comprise advantages of both the matrix polymer and the reinforcement element. Also, the matrix polymer having reinforcement elements shrink less than unfilled resins/polymers when subjected to any form of heat molding, thereby improving the dimensional control of molded parts and reduce the cost of composites. In many embodiments, the matrix polymer of the crown/sole member&#39;s  24 / 26  may be polycarbonate (PC), polyphenylene sulfide (PPS), polypropylene (PP), Nylon-6 (PA6), Nylon 6-6 (PA66), Nylon-12 (PA12), Polymethylpentene (TPX), polyvinylidene fluoride (PVDF), polymethylmacylate (PMMA), poly ether ketone (PEEK), polyetherimide (PEI), or polyether ketone (PEK). 
     The materials of, for example, the matrix polymer of the crown  18 , sole  20 , and/or strike face  30  each may be selected and/or formed to achieve one or more material properties such as tensile strength, tensile modulus, and density. The matrix polymer of the crown, sole, and/or strike face may comprise a tensile strength ranging from 30 MPa to 3000 MPa. In some embodiments, the tensile strength of the matrix polymer may range from 30 MPa to 500 MPa, 500 MPa to 1000 MPa, 1000 MPa to 1500 MPa, 1500 Pa to 2000 MPa, 2000 MPa to 2500 MPa, 2500 MPa to 3000 MPa, 30 MPa to 1500 MPa, 1500 MPa to 3000 MPa, 500 MPa to 2500 MPa, 30 MPa to 1000 MPa, 1000 MPa to 2000 MPa, or 2000 MPa to 3000 MPa. In some embodiments, the tensile strength of the crown, sole, and/or strike face&#39;s matrix polymer may be 30 MPa, 200 MPa, 400 MPa, 800 MPa, 1200 MPa, 1600 MPa, 2000 MPa, 2400 MPa, 2800 MPa, or 3000 MPa. 
     The matrix polymer of the crown, sole, and/or strike face may comprise a tensile modulus ranging from 1.5 GPa to 12 GPa. In some embodiment, the tensile modulus may range from 1.5 GPa to 6 GPa, 6 GPa to 12 GPa, 1.5 GPa to 3 GPa, 3 GPa to 6 GPa, 6 GPa to 9 GPa, or 9 GPa to 12 GPa. In some embodiments, the matrix polymer of the crown, sole, and/or strike face may have a tensile modulus of 1.5 GPa, 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, 11 GPa, or 12 GPa. 
     The matrix polymer of the crown, sole, and/or strike face may comprise a density ranging from 0.80 g/cm 3  to 1.80 g/cm 3 . In some embodiments, the density may range from 0.80 g/cm 3  to 1.3 g/cm 3 , 1.3 g/cm 3  to 1.8 g/cm 3 , 1.0 g/cm 3  to 1.6 g/cm 3 , 0.8 g/cm 3  to  1 .1 g/cm 3 , 1.1 g/cm 3  to 1.5 g/cm 3 , 1.5 g/cm 3  to 1.8 g/cm 3 , 0.8 g/cm 3  to 1.0 g/cm 3 , 1.0 g/cm 3  to 1.2 g/cm 3 , 1.2 g/cm 3  to 1.4 g/cm 3 , 1.4 g/cm 3  to 1.6 g/cm 3 , or 1.6 g/cm 3  to 1.8 g/cm 3 . In some embodiments, the matric polymer of the crown/sole may have a density of 0.8 g/cm 3 , 0.9 g/cm 3 , 1.0 g/cm 3 , 1.1 g/cm 3 , 1.2 g/cm 3 , 1.3 g/cm 3 , 1.4 g/cm 3 , 1.5 g/cm 3 , 1.6 g/cm 3 , 1.7 g/cm 3 , or 1.8 g/cm 3 . 
     The reinforcement fabrics/fibers embedded within one or more of the crown, sole, and/or strike face may be carbon fiber, aramid fibers (e.g., Nomex, Vectran, Kevlar, Twaron), bamboo fiber, natural fiber (e.g., cotton, hemp, flax), glass fibers, glass beads, metal fibers (e.g., Ti, Al), ceramic fibers (e.g., TiO2), and granite, SiC). The materials of such reinforcement fabrics/fibers within the crown, sole, and/or strike face comprises material properties such as tensile strength, tensile modulus and density. In some embodiments, the tensile strength of the crown, sole, and/or strike face&#39;s reinforcement elements range from 300 MPa to 7000 MPa. In some embodiments, the tensile strength of the reinforcement elements may range from 300 MPa to 4000 MPa, 4000 MPa to 7000 MPa, 2000 MPa to 5500 MPa, 300 MPa to 2000 MPa, 2000 MPa to 3500 MPa, 3500 MPa to 5000 MPa, 5000 MPa to 7000 MPa, 300 MPa to 1500 MPa, 1500 MPa to 2500 MPa, 2500 MPa to 3500 MPa, 3500 MPa to 4500 MPa, 4500 MPa to 5500 MPa, or 5500 MPa to 7000 MPa. In some embodiments, the reinforcement elements of the crown, sole, and/or strike face may have a tensile strength of 300 MPa, 1000 MPa, 1500 MPa, 2000 MPa, 2500 MPa, 3000 MPa, 3500 MPa, 4000 MPa, 4500 MPa, 5000 MPa, 5500 MPa, 6000 MPa, 6500 MPa, or 7000 MPa. 
     In some embodiments, the tensile modulus of the crown, sole, and/or strike face&#39;s reinforcement elements range from 30 GPa to 700 GPa. In some embodiments, the tensile modulus of the reinforcement elements may range from 30 GPa to 400 GPa, 400 GPa to 700 GPa, 200 GPa to 550 GPa, 30 GPa to 200 GPa, 200 GPa to 350 GPa, 350 GPa to 500 GPa, 500 GPa to 700 GPa, 30 GPa to 150 GPa, 150 GPa to 250 GPa, 250 GPa to 350 GPa, 350 GPa to 450 GPa,450 GPa to 550 GPa, or 550 GPa to 700 GPa. In some embodiments, the reinforcement elements of the crown, sole, and/or strike face may have a tensile Modulus of 30 GPa, 100 GPa, 150 GPa, 200 GPa, 250 GPa, 300 GPa, 350 GPa, 400 GPa, 450 GPa, 500 GPa, 550 GPa, 600 GPa, 650 GPa, or 700 GPa. 
     In some embodiments, the density of the reinforcement elements of the crown, sole, and/or strike face range from 0.75 g/cm 3  to 10 g/cm 3 . In some embodiments, the density of the reinforcement elements may range from 1 g/cm 3  to 5 g/cm 3 . In some embodiments, the reinforcement elements of the crown, sole, and/or strike face may be 1.8 kg/mm 2 , 200 kg/mm 2 , 400 kg/mm 2 , 600 kg/mm 2 , 800 kg/mm 2 , 1000 kg/mm 2 , 1200 kg/mm 2 , 1400 kg/mm 2 , 1600 kg/mm 2 , 1800 kg/mm 2 , 2000 kg/mm 2 , or 2200 kg/mm 2 . 
       FIGS. 34-35  illustrate an additional embodiment of a club head  10  that may be constructed, at least in part, according to the teachings above. As shown, the golf club head  10  includes a front body  14  and a rear body  16  that are secured together to define a substantially closed/hollow interior volume. In some embodiments, the front body  14  may be formed from metal (e.g., a titanium alloy or steel alloy). In other embodiments, however, at least a portion of the front body  14 , including the strike face  30 , may be formed from a filled thermoplastic and/or a fiber reinforced composite. In some embodiments, the front body  14  may be constructed as described above and/or illustrated in any of  FIGS. 11-18 . 
     The rear body  16  may generally be formed from a fabric reinforced thermoplastic composite crown member  500  forming at least a portion of the crown  18 , a fabric reinforced thermoplastic composite sole member  502  forming at least a portion of the sole  20 , and a filled or unfilled thermoplastic supporting structure  504  that supports one or both of the FRC crown member  500  or FRC sole member  502 . In some embodiments, the thermoplastic supporting structure  504  may include a plurality of discontinuous reinforcing fibers and/or a metallic fill (e.g., a powder) embedded within a thermoplastic resin. In a preferred embodiment, the thermoplastic resin of the supporting structure  504  is the same or otherwise miscible with the thermoplastic resin used to form both the FRC crown member  500  and the FRC sole member  502 . In this manner, the crown and sole members  500 ,  502  may be joined to the supporting structure  504  using direct bonding and without the need for intermediate adhesives. 
       FIG. 34  further illustrates the weighted portion  72  exploded out from the supporting structure  504 . In some embodiments, the weighted portion  72  may comprise a metal section that is adapted to receive one or more removable and/or fixed weights. In one embodiment, the weighted portion  72  may comprise a steel alloy that is adapted to receive one or more fixed or removable weights  40  comprising tungsten. In some embodiments, at least a portion of the weighted portion  72  may be mechanically engaged with the supporting structure  504  through, for example, an insert injection molding process. 
     In embodiments where the front body  14  and rear body  16  are formed primarily using thermoplastic composite materials, it has been found that the club head moments of inertia and total mass both drop rather substantially. More specifically, switching to this particular thermoplastic construction provides a design that is about 60 to about 100 grams lighter than conventional driver heads, which generally weigh between about 200 grams and about 210 grams. In order to maintain a constant swing weight with improved moments of inertia (i.e., resistance to club head twisting during off-center impacts), it is desirable to incorporate this mass back into the club head in the form of discretionary, placed mass. 
     In some embodiments, it may be desirable to locate at least a portion of the discretionary mass toward a forward portion of the club head. In some embodiments, it has been found that the use of a forwardly located mass provides a more stable and balanced club head. More particularly, it has been discovered that if the center of gravity is pushed rearward beyond approximately the geometric center where the club head, the club head may become unstable, particularly during the deceleration phase of the swing near impact. This concern has not arisen with traditional metal constructions due to the structural mass maintained in the forward regions of the club head. With the low density of polymers, and the increase in discretionary mass, however, it is a concern that must be accounted for in the design or placement of discretionary mass. 
       FIGS. 36-38  illustrate three embodiments of a front body  14  that is similar to that shown in  FIG. 34 . Each embodiment provides a different means of placing discretionary mass in the toe portion  24  and/or the heel portion  22  of the front body  14 .  FIG. 36  illustrates an embodiment of a thermoplastic composite front body  14  where mass pockets  510  are molded into an internal portion  512  of the front body  14 . Each mass pocket  510  may comprise a heavy metal such as lead, tungsten, or bismuth that is over-molded or encapsulated by a portion of the front body  14 . In one embodiment, to prevent the occurrence of unnecessary stress risers created at the boundary between the metal and the polymer, the metal may be integrated as a filler into a thermoplastic resin that is misable with the resin used to form the surrounding FT and/or FRC. In such an embodiment, the metal filler may form up to about 90%, or up to about 80%, or up to about 70%, or up to about 60% by volume of the weighted slug incorporated into the mass pocket  510 . In doing so, when the metal-filled polymer is over-molded, the abutting thermoplastic resins may form a stronger surface bond than a polymer to pure metal interface. 
       FIG. 37  illustrates a different embodiment of the design shown in  FIG. 36 . Finally,  FIG. 38  illustrates a design where the forward weights  514  in the front body  14  are at least partially mechanically affixed, such as through the use of one or more screws  516 . In one embodiment of such a design, an outer weight  518  may be affixed to an outer surface  520  of the club head, while an inner weight  522  may cooperate with the outer weight  518  to sandwich a portion of the club head wall. Both the inner weight  522  and the outer weight  518  may be formed from metal in an effort to most affect the location of the club head center of gravity. In one embodiment, the outer weight  518  may resemble a naming badge or applique. In some embodiments, the inner weight  522  may be at least partially separated from the club head wall via a gasket  524 . In one embodiment, each of the weights shown in  FIGS. 36-38  may be vertically aligned with the geometric center  526  of the face. In other embodiments, the weights may be located below the center of the face to help pull the center of gravity lower, which would generally result in a higher ball trajectory. 
       FIG. 39  illustrates an embodiment of a rear body  16  design that integrates a weight  530  in one or more forward portions  532  of the FRC crown member  500  or FRC sole member  502 . As shown in the cross-sectional view in  FIG. 40 , in one embodiment, these weights  530 may be encapsulated between two adjacent fabric-reinforced lamina layers  534 ,  536  used to form the sole member  502 . Similar to the design described above, in one embodiment, to prevent the occurrence of unnecessary stress risers created at the boundary between the weight  530  and the polymer of the FRC lamina layers  534 ,  536 , the metal may be integrated as a filler into a thermoplastic resin element having a polymeric resin that is misable with the resin used to form the surrounding FRC layers. In such an embodiment, the metal filler may be from about 30% to about 90% by volume of the weight  530 , alternatively, it may be from about 60% to about 80% by volume, or even about 65% to about 75% by volume of the weighted element. In some embodiments, the weight  530  may have a specific gravity of greater than about 8, or greater than about 9, or greater than about 10. In one particular embodiment the weight  530  may comprise a 70% tungsten filler in a 30% thermoplastic resin (by volume), and may have a specific gravity in the range of about 12.5 to about 14.0. In these embodiments, when the metal-filled polymer is over-molded, the abutting thermoplastic resins may bond with the similar resins used to form the weight, thus reducing any boundary layer stresses that may form. 
     It has been found that in some designs, the face thickness and density may provide sufficient forward weighting to avoid the need for additional forward metallic weights. In one embodiment, the forward weighting was found to not be required if the maximum thickness of the variable thickness strikeface was from about 5.0 mm to about 9.0 mm, or from about 6.0 mm to about 8.0 mm, with the perimeter thickness of from about 3.0 mm to about 5.0 mm, or from about 3.5 mm to about 4.5 mm. In one embodiment, forward metallic weights were not required when the maximum face thickness was about 7.25 mm and the surrounding perimeter face thickness was about 4.45 mm. 
     In one embodiment that utilizes no added forward metallic mass, all of the discretionary mass may be added to the club head in the form of a tungsten or other dense metal weight that is provided, for example, in a rear weighted portion  72  of the sole  20 . Such a design would aid in moving the center of gravity down and back, which improves the launch characteristics of an impacted ball. Unfortunately, in some circumstances a concentrated load of this nature may require a strengthened support structure between the weight and the strike face that may withstand the impact loading without catastrophically buckling. The further back, heavier, and more concentrated the mass becomes, the more structure and/or stiffer material would then be required to resist bucking of the intermediate portion of the club head. 
       FIGS. 41-42  schematically illustrate a design of the rear portion of a club head  550  that includes a weighted internal skeleton  552  that is operative to distribute weight in a structural manner while resisting impact buckling instead of encouraging it. As shown, in at least  FIG. 43 , the skeleton  552  includes a lower cage  554  and a perimeter band  556 . In some embodiments, the lower cage  554  is distinct from the perimeter band  556  such that absent any intermediate polymer, the two components would be disconnected and separate (such as shown in  FIG. 43 ). In some embodiments, the skeleton  552  may be formed from a metal material that is operative to alter the placement of the center of gravity. If formed from a metal material, the skeleton  552  may be adhered in place or overmolded (e.g., via insert injection molding). 
     In another embodiment, the skeleton  552  may be a thermoplastic composite that incorporates a metallic filler into a thermoplastic resin for at least one of the lower cage  554  and the perimeter band  556 . This hybrid thermoplastic skeleton may then be bonded/fused to abutting thermoplastic structure  504 , for example, on an inward-facing surface  558  of the structure  504 . In such an embodiment, the metal filler may be from about 30% to about 90% by volume of the filled portion of the skeleton  552 , alternatively, it may be from about 60% to about 80% by volume, or even about 65% to about 75% by volume of the filled portion of the skeleton  552 . In some embodiments, the filled portion of the skeleton  552  may have a specific gravity of greater than about 8, or greater than about 9, or greater than about 10. In one particular embodiment the filled portion of the skeleton  552  may comprise a 70% tungsten filler in a 30% thermoplastic resin (by volume), and may have a specific gravity in the range of about 12.5 to about 14.0. 
     During manufacturing the skeleton  552  may be compression molded in contact with the structure  504 , whereby each respective structure is heated to a temperature above the glass transition temperature of its respective resin. Upon cooling, the abutting parts may then be fused together. 
     In yet another embodiment, the supporting structure  504 , itself, may include a metallic filler that is operative to reintroduce a portion of the available discretionary weight. In such an embodiment, at least a portion of the structure  504  may have specific gravity of greater than about 8, or greater than about 9, or greater than about 10, or in the range of about 12.5 to about 14.0. 
       FIG. 44  schematically illustrates an exploded view of an embodiment of the rear body  16  with the sole member  502  shown in an exploded view. In this embodiment, the sole member  502  may comprise a plurality of layers with at least two of the layers being thermoplastic composites. In particular, the embodiment shown in  FIG. 44  includes an inner FRC sole layer  570 , an outer FRC sole layer  572 , and an intermediate weighting member  574  provided between the inner and outer FRC sole layers  570 ,  572 . In this embodiment, the weighting member  574  may be either a metallic plate, or may be a FT composite with a metallic filler disposed within a thermoplastic resin (such as described above).  FIGS. 45-47  then illustrate three different embodiments of an intermediate weighting member  574  that may be used with the multi-layered sole member  502 . 
     Common to each of the presently disclosed designs is a desire to provide a golf club head that maximizes the total amount of discretionary mass, which may be employed to locate the center of gravity as close to the sole and rear of the club as is possible within stability constraints, while maximizing the moment of inertia toward the maximum limits allowable under U.S.G.A. regulations. To accomplish this desire, one or both of a forward body  14  or rear body  16  of the club head  10  is formed from a reinforced thermoplastic composite that has a lower specific gravity than typically used metals. It has been found, however, that accomplishing adequate durability with polymers that are less strong than metals requires an increase in the volume of material required thus offsetting at least a portion of the weight savings. The presently described embodiments utilize a design-based approach to reinforcing the polymeric structure in a way that attempts to minimize the amount of additional material that must be added. These designs incorporate selective reinforcement to guard against buckling within primary load paths, utilize aligned reinforcing fibers embedded within the thermoplastic to tune the anisotropic strengths of the thermoplastic composites to the dynamics of the structure, and/or utilize a mixed material thermoplastic laminate structure to leverage the design and material advantages of both filled thermoplastics and fabric reinforced composites in the same structure. 
     The present designs have realized net weight savings of up to about 60 to 100 grams. Absent any reintroduction of this weight, the club head would realize a dramatic reduction in both swing weight and moment of inertia. Reintroduction of the weight, however, posed separate challenges in how specifically to attach the weight to the structure, how to distribute the weight to avoid impact dynamics that may damage intermediate structure, and how to locate the weight to maximize moments of inertia while pushing the center of gravity as far down and back as possible. The presently described embodiments for re-weighting the club head each attempt to balance these objectives, for example, by placing weight forward to minimize impact stresses and maintaining a center of gravity forward of a critical point that could result in instability, by distributing the weight in a structural manner, such as using a skeleton or metal-doped reinforcing structure or by incorporating the weight into weighted and/or doped lamina layers within the outer shell of the club head. Incorporation of the weight into the structure, itself, is a design that is made possible largely through the use of thermoplastic resins, which may be used to form discrete layers having specific design properties, and then subsequently reforming the collection of layers into a collective laminate stack-up. 
     As discussed below, the designs described herein have proved to be successful in achieving the design objectives of a high moment of inertia club head with a center of gravity that is pushed down and back while still maintaining stability and durability. 
     General Mass Properties 
     As generally illustrated in  FIGS. 48-49 , the strikeface  30  of the club head  10  defines a geometric center  800  and a loft plane  802  tangent to the geometric center  800  of the strikeface  30 . In some embodiments, the geometric center  800  may be located at the geometric centerpoint of a strikeface perimeter  804 , and at a midpoint of face height  806 . In the same or other examples, the geometric center  800  also may be centered with respect to engineered impact zone  808 , which may be defined by a region of grooves  810  on the strikeface. As another approach, the geometric center of the strikeface may be located in accordance with the definition of a golf governing body such as the United States Golf Association (USGA). For example, the geometric center of the strikeface may be determined in accordance with Section 6.1 of the USGA&#39;s Procedure for Measuring the Flexibility of a Golf Clubhead (USGA-TPX3004, Rev. 1.0.0, May 1, 2008) (available at http://www.usga.org/equipment/testing/protocols/Procedure-For-Measuring-The-Flexibility-Of-A-Golf-Club-Head/) (the “Flexibility Procedure”). 
     The club head  10  further comprises a head center of gravity (CG)  812  and a head depth plane  814  extending through the geometric center  800  of the strikeface  30 , perpendicular to the loft plane  802 , in a direction from the heel  22  to the toe  24  of the club head  10 . In many embodiments, the head CG  812  is located at a head CG depth  816  from the loft plane  802 , measured in a direction perpendicular to the loft plane  802 . The head CG  812  is further located at a head CG height  818  from the head depth plane  814 , measured in a direction perpendicular to the head depth plane  814 . In many embodiments, the head CG height  818  is positive when the head CG  812  is located above the head depth plane  814  (i.e. between the head depth plane  814  and the crown  18 ), and the head CG height  818  is negative with the head CG  812  is located below the head depth plane  814  (i.e. between the head depth plane  814  and the sole  20 ). 
     In many embodiments, the head CG height  818  may be less than 0.08 inches, less than 0.07 inches, less than 0.06 inches, less than 0.05 inches, less than 0.04 inches, less than 0.03 inches, less than 0.02 inches, less than 0.01 inches, or less than 0 inches (i.e. the head CG height may have a negative value, such that it is located below the head depth plane). Further, in many embodiments, the head CG height  818  may have an absolute value less than approximately 0.08 inches, less than approximately 0.07 inches, less than approximately 0.06 inches, less than approximately 0.05 inches, or less than approximately 0.04 inches. Further still, in many embodiments, the head CG depth  816  may be greater than approximately 1.7 inches, greater than approximately 1.8 inches, greater than approximately 1.9 inches, greater than approximately 2.0 inches, greater than approximately 2.1 inches, greater than approximately 2.2 inches, or greater than approximately 2.3 inches. 
     In many embodiments of the present designs, the head CG depth  816  and the head CG height  818  may be related by Relation 1 and/or Relation 2 below: 
     
       
         
           
             
               
                 
                   
                     Head 
                      
                     
                         
                     
                      
                     CG 
                      
                     
                         
                     
                      
                     Depth 
                   
                   ≥ 
                   
                     
                       
                         Head 
                          
                         
                             
                         
                          
                         CG 
                          
                         
                             
                         
                          
                         Height 
                       
                       + 
                       0.115 
                     
                     0.10 
                   
                 
               
               
                 
                   Relation 
                    
                   
                       
                   
                    
                   1 
                 
               
             
             
               
                 
                   
                     Head 
                      
                     
                         
                     
                      
                     CG 
                      
                     
                         
                     
                      
                     Depth 
                   
                   ≥ 
                   
                     
                       
                         Head 
                          
                         
                             
                         
                          
                         CG 
                          
                         
                             
                         
                          
                         Height 
                       
                       + 
                       0.14 
                     
                     0.10 
                   
                 
               
               
                 
                   Relation 
                    
                   
                       
                   
                    
                   2 
                 
               
             
           
         
       
     
     For the purpose of determining club head moments of inertia, a coordinate system may be defined at the CG  812  via mutually orthogonal axes (i.e., an x-axis  820 , a y-axis  822 , and a z-axis  824 ). The y-axis  822  extends through the head CG  812  from the crown  18  to the sole  22 , perpendicular to a ground plane when the club head is at an address position. The x-axis  820  extends through the head CG  812  from the heel  22  to the toe  24  and perpendicular to the y-axis  822 . The z-axis  824  extends through the head CG  812  from the front end  830  to the back end  832  and perpendicular to the x-axis  820  and the y-axis  822 . 
     Moments of inertia then exist about the x-axis Ixx (i e crown-to-sole moment of inertia) and about the y-axis Iyy (i.e. heel-to-toe moment of inertia). In many embodiments, the crown-to-sole moment of inertia Ixx may be greater than approximately 3000 g·cm 2 , greater than approximately 3250 g·cm 2 , greater than approximately 3500 g·cm 2 , greater than approximately 3750 g·cm 2 , greater than approximately 4000 g·cm 2 , greater than approximately 4250 g·cm 2 , greater than approximately 4500 g·cm 2 , greater than approximately 4750 g·cm 2 , greater than approximately 5000 g·cm 2 , greater than approximately 5250 g·cm 2 , greater than approximately 5500 g·cm 2 , greater than approximately 5750 g·cm 2 , greater than approximately 6000 g·cm 2 , greater than approximately 6250 g·cm 2 , greater than approximately 6500 g·cm 2 , greater than approximately 6750 g·cm 2 , or greater than approximately 7000 g·cm 2 . Further, in many embodiments, the heel-to-toe moment of inertia Iyy may be greater than approximately 5000 g·cm 2 , greater than approximately 5250 g·cm 2 , greater than approximately 5500 g·cm 2 , greater than approximately 5750 g·cm 2 , greater than approximately 6000 g·cm 2 , greater than approximately 6250 g·cm 2 , greater than approximately 6500 g·cm 2 , greater than approximately 6750 g·cm 2 , or greater than approximately 7000 g·cm 2 . 
     In many embodiments, the club head comprises a combined moment of inertia (i.e. the sum of the crown-to-sole moment of inertia Ixx and the heel-to-toe moment of inertia Iyy) greater than 8000 g·cm 2 , greater than 8500 g·cm 2 , greater than 8750 g·cm 2 , greater than 9000 g·cm 2 , greater than 9250 g·cm 2 , greater than 9500 g·cm 2 , greater than 9750 g·cm 2 , greater than 10000 g·cm 2 , greater than 10250 g·cm 2 , greater than 10500 g·cm 2 , greater than 10750 g·cm 2 , greater than 11000 g·cm 2 , greater than 11250 g·cm 2 , greater than 11500 g·cm 2 , greater than 11750 g·cm 2 , or greater than 12000 g·cm 2 , greater than 12500 g·cm 2 , greater than 13000 g·cm 2 , greater than 13500 g·cm 2 , or greater than 14000 g·cm 2 . 
     Table 1, below numerically illustrates the mass parameters for eight different club heads. Specifically, the table shows the CG depth  816 , CG height  818 , moment of inertia Ixx about the horizontal x-axis  820 , and moment of inertia Iyy about the y-axis  822 . 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Mass properties of various driver head designs. 
               
            
           
           
               
               
               
               
               
            
               
                   
                 CG Depth 
                 CG Height 
                 Ixx 
                 Iyy 
               
               
                 Club 
                 (CGz) 
                 (CGy) 
                 (g · cm 2 ) 
                 (g · cm 2 ) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Metal 1 
                 1.716 
                 0.111 
                 3802.1 
                 5258.2 
               
               
                 Metal 2 
                 1.721 
                 0.086 
                 3770.6 
                 5382.6 
               
               
                 Metal 3 
                 1.840 
                 0.082 
                 4312.3 
                 5789.5 
               
               
                 Metal Face; 
                 1.780 
                 0.140 
                 3954.5 
                 5292.0 
               
               
                 Polymer Body 
               
               
                 Polymer Face; 
                 2.031 
                 0.103 
                 3892.4 
                 5443.7 
               
               
                 Metal Body 
               
               
                 All Polymer 1 
                 2.015 
                 0.038 
                 3716.8 
                 5499.0 
               
               
                 All Polymer 2 
                 2.384 
                 0.078 
                 4725.2 
                 5949.7 
               
               
                 All Polymer 3 
                 2.416 
                 0.005 
                 5096.1 
                 6103.2 
               
               
                   
               
            
           
         
       
     
     Metal clubs 1-3 are all commercially available drivers having an all metal structural design (i.e., at least the crown, sole, and face). Metal 1 is a metal driver head with a full titanium structure, a volume of less than about 445 cm 3 , and a rear backweight. Metal 2 is metal driver head with a full titanium structure, a volume of greater than or equal to 460 cm 3 , and a rear backweight. Metal 3 is a metal driver head with a full titanium structure, a volume of in the range of about 450-457 cm 3 , and a movable weighting system. 
     “Metal Face; Polymer Body” is a driver head of similar construction as is shown in  FIGS. 1-3 , with a titanium front body  14  and a rear body  16  that is substantially formed from a polymeric composite structure. Metallic weights are added into the rear weighted portion to provide a similar swing weight as the commercially available all-metal driver heads. “Polymer Face; Metal Body” is a driver head that includes a polymer front body  14 , such as shown in  FIGS. 11-13 , which is affixed to an optimized titanium rear body  16  that is substantially similar to the titanium rear portions of Metal 1 or Metal 2. 
     Finally, “All Polymer 1” is a polymeric composite driver head that includes a polymeric front body  14 , such as shown in  FIGS. 11-13 , mated with a polymeric rear body  16 , such as shown in any or all of  FIGS. 1-7 , with weight being re-introduced in a moderately distributed manner including at least some discretionary weighting provided forward of the center of gravity. “All Polymer 2” builds on the design of “All Polymer 1” by moving discretionary mass rearward in the form of an 80 gram tungsten weight placed in the furthest practical location at the rear of the club and as close to the sole as possible. Finally, “All Polymer 3” is a theoretical model that replaces the 80 gram weight of “All Polymer 2” with an 80 gram point mass placed at the rearmost point of the club head and as close to the sole as possible. 
       FIG. 50  graphically represents the CG location, with the vertical axis  900  representing CGy (CG height  818 ) and the horizontal axis  902  representing CGz (CG depth  816 ) for each of the club head embodiment identified in Table 1.  FIG. 50  further groups the various models into three categories: a first group  904  consisting of commercially available, all-metal drivers (i.e., Metal 1, Metal 2, and Metal 3); a second group  906  consisting of designs where a portion of the club head has been converted to a polymeric composite (i.e., “Metal Face; Polymer Body” and “Polymer Face; Metal Body”); and the third grouping  908  consists of designs where the entire structure has been converted to a polymeric construction (i.e., All Polymer 1, All Polymer 2, and All Polymer 3).  FIG. 50  further illustrates the two relations discussed above (“Relation 1”  910  and “Relation 2”  912 ). 
       FIG. 50  demonstrates graphically, that a CG shift both lower and deeper (relative to the commercial, all-metal designs) is realized only by moving entirely to an all-polymer structure. As shown, the use of a partial polymer structure in the present designs may actually result in a higher CG, which may work against an ideal ball flight and reduce total distance. Furthermore, referring again to Table 1, these all-polymer designs (particularly where there is little or no forward discretionary mass, such as in All Polymer 2 and 3), may result in very substantial increases in the club head moments of inertia. For example, the “All Polymer 2” design, which has an 80 gram tungsten weight in the rear, provides a 19% gain in Ixx over an average Ixx from the all-metal designs, and provides a 9% gain in Iyy over the average Iyy from the all-metal designs. For comparison sake, it should be noted that each design provided in Table 1 has approximately the same mass (+/−about 3 grams). 
       FIGS. 51-55  schematically illustrate an embodiment of a golf club head  1000  that includes a metallic first component  1014  and one or more non-metallic body portions  1016 . When fully assembled, the first component  1014  and the non-metallic body portions  1016  cooperate to define a hollow, interior clubhead volume, as is present in a traditional metal-wood. Much like the embodiments described above, the metallic first component  1014  generally includes a forward portion  1018  that includes a strike face  30  intended to impact a ball during a normal golf swing, and a frame  32  that surrounds and extends rearward from a perimeter  34  of the strike face  30  to provide the front body with a cup-shaped appearance. Unlike many of the above-described embodiments, however, the first component  1014  further includes a metallic sole extension  1020  that generally projects rearward from the frame  32  to give the first component  1014  a “T” shaped appearance when viewed from above. 
     As shown by  FIG. 52 , the sole extension  1020  may be angled relative to the strike face  30  of the first component  1014 . The first component  1014  forms a sole extension toe-ward angle  1050  and a sole extension heel-ward angle  1055 . The sole extension toe-ward angle  1050  and the sole extension heel-ward angle  1055  are supplementary angles (i.e. the two angles add up to 180 degrees). In one embodiment, the toe-ward angle  1050  and the heel-ward angle  1055  are each 90 degrees, so the sole extension  1020  is essentially perpendicular to the strike face  30 . In alternate embodiments, the toe-ward angle  1050  and the heel-ward angle  1055  may each vary between 45 degrees and 135 degrees, as long as the two angles continue to be supplementary angles. For example, the toe-ward angle  1050  may be 100 degrees, while the heel-ward angle  1055  is the supplementary 80 degrees. In this example, the rear end of the sole extension  1020  is angularly offset towards the heel end  22  of the golf club head  1000 . Other combinations of toe-ward angle  1050  and heel-ward angle  1055  may be 110 degrees and 70 degrees, 120 degrees and 60 degrees, 130 degrees and 50 degrees, or 135 degrees and 45 degrees. 
     Angling the sole extension  1020  relative to the strike face  30  may offset the CG  812  of the golf club head  1000  towards either the heel end  22  or the toe end  24 . For example, the center of gravity may be offset towards the heel end  22  0.010 inch, 0.020 inch, 0.030 inch, 0.040 inch, 0.050 inch, 0.060 inch, 0.070 inch, 0.080 inch, 0.090 inch, 0.100 inch, 0.110 inch, 0.120 inch, 0.130 inch, 0.140 inch, or 0.150 inch. In a similar fashion, the toe-ward angle may decrease while the heel-ward angle increases. For example, the combination of toe-ward angle  1050  and heel-ward angle may be 80 degrees and 100 degrees, 70 degrees and 110 degrees, 60 degrees and 120 degrees, 50 degrees and 130 degrees, or 45 degrees and 135 degrees. For example, the center of gravity may be offset towards the toe end  24  by 0.010 inch, 0.020 inch, 0.030 inch, 0.040 inch, 0.050 inch, 0.060 inch, 0.070 inch, 0.080 inch, 0.090 inch, 0.100 inch, 0.110 inch, 0.120 inch, 0.130 inch, 0.140 inch, or 0.150 inch. This angular offset may be desirable to place a rear mass more toward the rear, heel-ward portion or rear toe-ward portion to position a club head center of gravity in that direction to influence ball flight characteristics. Other angular offsets in different embodiments may differently combine the first component sole portion rear extension toe-ward angle  1050  and the first component sole portion rear extension heel-ward angle  1055 , which may produce different club head center of gravity positions and different ball flight characteristics. 
     In some embodiments, the sole extension  1020  may have a varying width. In these embodiments, the toe-ward angle  1050  and the heel-ward angle  1055  may not be supplementary angles (may not sum to 180 degrees). In some embodiments, both the toe-ward and the heel-ward angles ( 1050  and  1055 ) of the sole extension  1020  may be acute angles, reducing the weight of the first component  1014  and allowing greater perimeter weighting in the club head  1000 . In other embodiments, both the toe-ward and the heel-ward angles ( 1050  and  1055 ) may be obtuse angles, increasing the durability of the sole and simplifying manufacturing assembly of the golf club head  1000 . 
     In some embodiments, both the toe-ward and heel-ward angles ( 1050  and  1055 ) are obtuse angles, such that the width of the sole extension  1020  decreases in a front-to-rear direction. This configuration is desirable in embodiments wherein the non-metallic portion  1016  is a unitary piece. In such embodiments, the non-metallic portion  1016  is generally slid onto the first component  1014  in a front-to-rear direction. Accordingly, in such embodiments, the sole extension  1020  must be narrowest at the rear edge of the sole extension  1020  to allow the non-metallic portion  1016  to slide smoothly and fit properly along the first component  1014 . Additional embodiments of this design are described in U.S. Pat. No. 10,596,427 as well as U.S. Patent Application Publication Nos. 2020/0298072 and 2020/0179774, which are all incorporated by reference in their entirety. 
     The sole extension  1020  may serve to structurally couple a sole portion  1022  of the frame  32  with a weight assembly  1072  at or near the rear of the clubhead. The weight assembly  1072  extends upward from the sole  1022  and forms a middle portion of the rear of the club head  1000 . The weight assembly  1072  forms only a lower portion of the rear, it does not extend above a perimeter edge  1104  of the golf club head  1000 . Further, the weight assembly  1072  does not form a cup shape of any kind. The transition between the sole extension  1020  and the weight assembly  1072  is a generally distinct and angled transition. The transition between the sole extension  1020  and the weight assembly  1072  is not a gradual transition and the interior of weight assembly  1072  does not comprise smooth, concave surfaces forming a cup. 
     In many embodiments, the weight assembly  1072  may be configured to receive a detachable weight member  1090  that has a greater specific gravity than the metal used to form the sole extension  1020  or forward portion  1018 . In some embodiments, the detachable weight member  1090  may include one or more threaded inserts that are operative to secure the detachable weight member  1090  to the first component  1014 . 
     As shown in  FIG. 54-55 , the weight assembly  1072  comprises three threaded receivers positioned relatively close to one another. A distance  1083  measured between the threaded receivers may be relatively small. For example, the distance  1083  separating adjacent threaded receivers may vary in a range from 0.5 inch to 0.6 inch. The distance  1083  separating the threaded receivers may be approximately 0.5 inch or approximately 0.6 inch. The detachable weight member  1090  may be positioned in three different positions within the weight assembly  1072 , corresponding to each threaded receivers for influencing a straight ball flight, a right to left ball flight, or a left to right ball flight. 
     In some embodiments, the weight assembly  1072  may comprise a weight channel  1074  configured to receive the detachable weight member  1090 . The weight channel  1074  may be recessed within the weight assembly  1072  such that a large portion of the detachable weight member  1090  sits within the recessed channel  1074  and does not extend past the perimeter of the golf club head  1000 . Rather than a curvilinear channel that follows the curvature of the club head body, the weight channel  1074  comprises a plurality of straight sections that are angled with respect to one another. Thus, the weight assembly  1072  does not comprise continuous concave or convex surfaces when viewed from either the interior or the exterior of the golf club head  1000  but instead forms a plurality of disjointed, flat surfaces. The transitions between these disjointed, flat surfaces are sharp angles that distinctly define where each section begins and ends. In some embodiments, the weight channel  1074  may comprise three of such sections, one corresponding to each of the threaded receivers. In one embodiment, the detachable weight member  1090  may be configured in the weight assembly  1072  of the golf club head  1000  to set up in a neutral position to hit a straight golf shot. The weight member  1090  couples to a central threaded receiver  1081   b  of the weight assembly  1072 . The central positioning of the weight member  1090  within the weight assembly  1072  leads to a generally straight ball flight, as the center of gravity or CG  812  of the entire golf club head  1000  is extremely balanced. 
     In another embodiment, the detachable weight member  1090  may be configured in the weight assembly  1072  of the golf club head  1000  to set up a heel-ward position, to hit a fade type golf shot. The weight member  1090  couples to a heel-side threaded receiver  1081   a  of the weight assembly  1072 . The heel-ward positioning of the weight member  1090  within the weight assembly  1072  leads to a generally left to right ball flight (for lefthanded golfers a right to left ball flight), as the entire golf club head CG  812  is off center towards the heel portion  22  of the golf club head  1000 . In another embodiment, the detachable weight member  1090  may be configured in the weight assembly  1072  of the golf club head  1000  to set up a toe-ward position, to hit a draw type golf shot. The weight member  1090  couples to a toe-side threaded receiver  1081   c  of the weight assembly  1072 . The toe-ward positioning of the weight member  1090  within the weight assembly  1072  leads to a generally right to left ball flight (for righthanded golfers a left to right ball flight), as the entire golf club head CG  812  is off center towards the toe portion  24  of the golf club head  1000 . 
     In many embodiments, the mass of the weight member  1090  ranges between 1 g and 40 g. In some embodiments, the mass of the weight member  1090  ranges from 1 g-5 g, 5 g-10 g, 10 g-15 g, 15 g-20 g, 20 g-25 g, 25 g-30 g, 30 g-35 g, or 35 g-40 g. 
     The combination of a weight assembly  1072  in the rear portion with relatively small distances between weight positions and a single, heavy weight member  1090  leads to improvements in CG movement and MOI preservation. The small maximum separation between weight positions provides a smaller displacement of the weight member  1090  towards the heel  22  or toe  24  of the golf club head  1000 , but the heavier weight member  1090  counterbalances the smaller displacement of the weight member  1090 , allowing the user to shape golf ball flight by using a comparatively smaller weight member displacement while also preserving more of the total MOI and forgiveness of the golf club head  1000 . 
     Table 1 below displays the positioning of the center of gravity (CG)  812  of an exemplary golf club head  1000  with a similar weight assembly, as the detachable weight  1090  is reconfigured within the weight assembly  1072 . The golf club head CG  812  is displaced in terms of movement parallel to the x-axis  820 , the y-axis  822 , and the z-axis  824 . The CG  812  differential movement in inches parallel to the X-axis is the CGx. The differential movement in inches parallel to the Y-axis is the CGy. The differential movement in inches relative to the Z-axis is the CGz. The results below were compiled from a 35 gram tungsten weight, a 199 g golf club head weight, and with 0.6 inches of reconfiguration (a 0.6 inch distance  1083  between threaded receivers) within the weight assembly  1072  relative to the central threaded receiver  1081   b  when the detachable weight  1090  is moved to either the heel-side threaded receiver  1081   a  or the toe-side threaded receiver  1081   c.    
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 CG position with Weight Assembly Movement 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Weight Member Position 
                 CGx 
                 CGy 
                 CGz 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Heelward 
                 0.068 
                 0.829 
                 −2.003 
               
               
                   
                 Center 
                 −0.027 
                 0.835 
                 −2.041 
               
               
                   
                 Toeward 
                 −0.122 
                 0.841 
                 −2.041 
               
               
                   
                   
               
            
           
         
       
     
     Referring to Table 1, above, the movement of CGx is approximately 0.04 inch towards the heel  22  or 0.09 inch towards the toe  24  from the starting center position when the weight member  1090  is placed in either the heel-side threaded receiver  1081   a  or the toe-side threaded receiver  1081   c . However, the movements of CGy and CGz are significantly smaller (less than 0.01 inch and 0.04 inch respectively). 
     In the exemplary golf club head  1000 , each 0.01 inch of CGx shift towards either the heel  22  or toe  24  resulted in a ball flight bias of approximately 1 yard. For example, with the weight member  1090  in the heel-ward position, the approximately 0.09 inch CGx shift towards the heel produced a ball flight biased to fade from left-to-right (for a right handed golf club) approximately 9 yards more than the same golf club head  1000  with the weight member  1090  in the center position. Similarly, with the weight member  1090  in the toe-ward position, the approximately 0.04 inch CGx shift towards the toe  24  produced a ball flight biased to draw from right-to-left (for a right handed golf club) approximately 4 yards more than the same golf club head  1000  with the weight member  1090  in the center position. 
     The recessed channel  1074  of the weight assembly  1072  displaces a small amount of mass from the rear of the golf club head  1000 . Many prior art golf club heads comprise weight channels disposed over a large surface area of the heel, rear, and toe that displace large amounts of mass from the rear of said prior art golf club heads, undesirably pushing the center of gravity of said prior art club heads far forward towards the face and decreasing forgiveness. Due to the compact design of the weight assembly  1072  of the present club head  1000 , the amount of mass removed from the rear is negligible with respect to its effect on the club head CGz. 
     In one example, the CGz of the golf club head  1000  with the weight member  1090  detached was measured and compared to the center of gravity position of a similar golf club head devoid of a weight channel. The CGz of the club head with no weight channel was −1.632 inches (measured rearward of the strike face). The CGz of the club head comprising a weight channel  1074  but no weight member  1090  was −1.520 inches. Further, when the weight member  1090  was reintroduced into the exemplary golf club head  1000 , the CGz position shifted all the way back to −2.041 inches. Introducing a compact weight channel  1074  by itself does bring the CG forward, however, this effect is negligible compared to the rearward CG shift achieved by introducing the heavy weight member  1090 . The heavy weight member  1090  offsets the forward CGz shift of including the weight channel  1074  and positions the CG at a desirable depth to produce the desired ball flight while still providing a high level of forgiveness. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 MOI change with Weight Assembly Movement 
               
            
           
           
               
               
               
            
               
                   
                   
                 % Change of Combined 
               
               
                   
                 Weight Member Position 
                 Club Head MOI 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                   
                 Heelward 
                 −3.4% 
               
               
                   
                 Center 
               
               
                   
                 Toeward 
                 1.7% 
               
               
                   
                   
               
            
           
         
       
     
     Further, the total moment of inertia or MOI decrease of the golf club head  1000  is minimized. Referring to Table 2, above, the change of total MOI for the same golf club head  1000  is a very small 3.4% decrease when the weight member  1090  is shifted to the heel-side threaded receiver  1081   a , and the total golf club head MOI actually increases by 1.7% when the weight member  1090  is shifted to the toe-side threaded receiver  1091   c . Thus, as the CG  812  of the golf club head  1000  is moved in a heelward or toeward direction, the forgiveness of the golf club head  1000  is largely preserved. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 MOI change with Weight Assembly Movement -Prior Art 
               
            
           
           
               
               
               
            
               
                   
                   
                 % Change of Combined 
               
               
                   
                 Weight Member Position 
                 Club Head MOI 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                   
                 Heelward 
                 −11.0% 
               
               
                   
                 Center 
               
               
                   
                 Toeward 
                 −3.4% 
               
               
                   
                   
               
            
           
         
       
     
     Referring to Table 3, above, a comparison of a similar, prior art golf club head has an 11.0% decrease in total golf club head MOI when the weight assembly is configured in a most heelward position, and 3.4% decrease when the weight assembly is configured in a most toeward position. 
     Further, the compact design of the overall structure of the weight assembly  1072  provides weight savings compared to the larger weight assemblies of prior art golf club heads. These weight savings allow the golf club head  1000  to comprise a greater overall volume without making the club head  1000  too heavy. Increasing the overall volume of the golf club head  1000  in this way increases MOI and provides a more forgiving golf club head  1000 . Further, enabling a short weight channel  1072  that does not wrap around a significant portion of the heel and toe peripheries of the club head  1000  allows a greater portion of the club head  1000  to be formed by the non-metallic portion  1016 . This creates even greater weight savings that can be reintroduced throughout the club head  1000  to further maximize MOI. 
     In one example, MOI values of an exemplary golf club head  1000  with a volume of  462  cubic centimeters and a compact weight assembly  1072  with a channel length  1076  of 1.84 inches were compared to a similar golf club head with a volume of 457 cubic centimeters and a weight assembly with a channel length of 4.65 inches. The exemplary golf club head  1000  with the higher overall volume and compact weight channel  1074  comprised a heel-to-toe moment of interia (Iyy) of 5655 g*cm 2  and a crown-to-sole moment of inertia (Ixx) of 4272 g*cm 2  while golf club head with the lower overall volume and the longer weight channel comprised a heel-to-toe moment of interia (Iyy) of only 5184 g*cm 2  and a crown-to-sole moment of inertia (Ixx) of only 3503 g*cm 2 . 
     In some configurations, this “T” shaped design may further include one or more crown braces  1030  that extend between the weighted portion  1072  and a crown portion  1024  of the frame  32 . The crown braces  1030  may serve to buttress the weighted portion  1072  against vertical motion throughout the dynamics of the swing and impact, while also stiffening the crown against different vibration modes. In some designs, the crown brace  1030  may further aid in manufacturing the first component (e.g., maintaining dimensional tolerances during a casting process). 
     With continued reference to  FIGS. 51-55 , the non-metallic rear body portions  1016  may comprise at least two polymeric panels  1100 ,  1102  that are operative to stiffen and streamline the overall external geometry of the clubhead  1000  As with the designs discussed above, in some embodiments, the design provided in  FIGS. 51-55  may utilize an FRC (fabric reinforced composite) material to form some or all of the resilient outer shell of the panels  1100 ,  1102  while using an FT (filled thermoplastic) material to locally enhance strength and stability of the panel, or to facilitate connection between the panel and the adjoining metal portions of the body. 
     In one particular configuration, each panel  1100 ,  1102  may wrap around an outer peripheral edge  1104  (best shown in  FIGS. 51-52 ) of the club head  1000  such that it extends across a portion of both the crown  18  and the sole  20 . The outer peripheral edge  1104  may specifically be defined as an outer perimeter of the rear of the club head (i.e., everything behind the strikeface  30 ) when viewed from the top, and/or may be defined an outer location of the body that has a vertical tangent when the club head  1000  is held in an address position on a horizontal ground plane according to predefined loft and lie angles. 
     In some embodiments, a first panel  1100  may be a heel-side body panel  1100  while a second panel  1102  may be a toe-side body panel  1102 . The heel-side body panel  1100  may extend from a heel-side of the crown brace  1030  to a heel-side of the sole extension  1020  across the outer peripheral edge  1104 . Likewise, the toe-side body panel  1102  may extend from a toe-side of the crown brace  1030  to a toe-side of the sole extension  1020  across the outer peripheral edge  1104 . 
     As further shown in  FIG. 53 , each panel may include an FRC resilient layer  1054  bonded to a FT structural layer  1056 . Each layer may comprise a thermoplastic resin to enable the adjacent layers  1054 ,  1056  to be fused together without the use of an intermediate adhesive, such as described above. In one configuration, the structural layer  1056  of each panel  1100 ,  1102  may substantially extend around the perimeter edge  1104  of the respective panel. Further, in some configurations, a reinforcing portion  1108  (i.e., “perimeter reinforcement  1108 ) of the structural layer  1056  may extend across an interior portion the panel and along the outer peripheral edge  1104  of the club head. This reinforcing portion  1108  could serve to provide an additional stabilizing load path between the face and the weighted portion, increase the modal response of the panel, and further improve the crush-resistance of the respective panel along the outer peripheral edge  1104  of the club head  10 . 
     As with many of the designs shown and discussed above, the structural layer  1056  of the design in  FIG. 53  includes an engineered geometry that thins or eliminates portions of the layer where increased strength/stiffness is not specifically required. In the embodiment shown in  FIG. 53 , these cored out portions may resemble one or more apertures in the structural layer. More specifically,  FIG. 53  illustrates a sole aperture  1110  and a crown aperture  1112  on opposite side of the perimeter reinforcement  1108 . The resilient layer  1056  may then extend entirely across both the sole aperture  1110  and crown aperture  1112 . 
     The polymeric panels  1100 ,  1102  may be secured to the first component, for example, by adhering the panel to a recessed feature, such as a flange or crown brace  1030 . This technique is best shown in  FIG. 7  and is equally applicable to the design of  FIGS. 51-55 . As further illustrated in  FIG. 51 , the resilient layer  1056  of each of the polymeric panels  1100 ,  1102  may meet at a seam  1120 . In some embodiments, the seam  1120  may be oriented such that it is parallel with (and/or aligned along) a bisecting lengthwise axis L of the crown brace  1030  (best illustrated in  FIGS. 53-55 ). In doing so, both panels may be adhered to the brace  1030  across a comparable area. To promote an adequate bond strength, the panels  1100 ,  1102  may meet the crown brace  1030  to form a lap joint and/or a tongue-in-groove joint. In a tongue-in-groove type joint, it may be preferable for the crown brace  1030  to be slightly recessed from the outer surface of the club head and configured to slide within a recess formed into the edge of the panel (e.g., by the FT structural layer). In such a design, assembly of the panels  110 ,  1102  onto the first component  1014  may simply involve sliding the panels laterally only to the body from the respective heel and toe sides (i.e., where the groove provided on the seam-edge of the panel would slide over a portion of the flat crown brace  1030 ). 
     Instead of using a metal crown brace  1030 , some embodiments may alternatively use a polymeric crown brace to secure the adjacent panels  1100 ,  1102  together and stiffen the crown structure. In such an embodiment, the structural layer of one of the two panels may include a thickened portion that extends beyond the FRC resilient layer. When assembled, the adjacent panel may overlap this ledge much in the same way it is shown to overlap the metal crown brace  1030 . The two panels may be secured to each other, for example, through the use of an adhesive, or alternatively by welding/fusing the thermoplastic from the adjacent parts to each other. Examples of suitable fusing techniques may include, for example, ultrasonic welding, spin welding, laser welding, or the like. 
       FIGS. 56A-56B  and  FIGS. 57A-57B  illustrate two alternate non-metallic body portions  1016  that are each adapted to extend across a portion of the crown  18  of the club head  1000 , while also wrapping around an outer peripheral edge  1104  to further cover a portion of the sole  20 .  FIGS. 56A-56B  schematically illustrate a first composite body panel  1200  that includes both an outer resilient layer  1054  and an inner structural layer  1056 . In the illustrated embodiment, the inner structural layer may extend around an edge of the panel, and further along an outer peripheral edge  1104  of the club head to define a plurality of apertures  1202  (including one crown aperture  1112 , and a plurality of smaller sole apertures  1110  or comparatively thinned sections. The resilient layer may extend across each of these apertures to provide a substantially continuous outer surface. 
       FIGS. 57A-57B  schematically illustrate a second composite body panel  1220  that is similar to the first body panel  1200 , though further includes a portion of the FT structural layer  1056  on an outer surface of the panel  1220 . This embodiment may enable the FRC material of the resilient layer  1054  to be provided in discrete panels that do not have to wrap continuously around the complex curve that defines the outer peripheral edge  1104  of the club head (i.e., complex in the sense that it arcs in two substantially orthogonal planes). In such an embodiment, the fabric of the resilient layer may comprise at least three discrete pieces: one across the crown  18 , and two on the sole  20 . 
     While the present disclosure primarily discusses the fabric reinforced composite resilient layer  1054  and the filled thermoplastic structural layer  1056  as being formed, in part, using a thermoplastic resin, in other embodiments, it may be possible to form similar designs with the use of a thermosetting resin (e.g., via a molding process such as compression molding of one or more prepregs or resin pre-forms, or through an injection molding process that is specifically tailored to thermosetting resins) or a cross-linked thermoplastic resin. 
     Furthermore, in some alternate embodiments, the composite body panels  1200 ,  1220  may be formed with only a reinforced composite resilient layer  1054  and without a filled thermoplastic structural layer  1056 . For instance, the composite body panels  1200 ,  1220  may be formed from only compression-molded prepregs without a cooperating structural support layer  1056 . In yet other embodiments, the composite body panels  1200 ,  1220  may be formed with only a filled thermoplastic layer, which may be manufactured through injection molding. 
       FIG. 58  schematically illustrates a golf club head  1300  that has a first component  1302  forming at least a portion of the crown  18  and strikeface  30 ; and a second component  1304  forming the sole  20  and hosel  36 . The first component  1302  and second component  1304  are joined together to define a substantially closed/hollow interior volume between the two components. To shift the center of gravity (CG) as low and as rearward as possible (thus improving launch characteristics and providing improved control), the first component  1302  may be substantially formed from a thermoplastic composite material, while the second component  1304  may be substantially formed from a metallic material. 
       FIG. 59  schematically illustrates a cross-sectional view of the first component  1302  of the golf club head  1300  shown in  FIG. 58  mating with a portion of the second component  1304 . As shown in both  FIGS. 58-59 , the first component  1302  may comprise a crown portion  1306  and a face portion  1308 . The crown portion  1306  forms at least a part of the crown  18 , and the face portion  1308  forms at least a part of the strikeface  30 . The crown portion  1306  is integrally connected to the face portion  1308  so that the first component  1302  is a single unitary structure/component. The unity of the crown and face portions  1306 ,  1308  eliminates the need for a junction (e.g., weld line or adhesively bonded junction) between the two portions, which may otherwise be more susceptible to structural weakness. 
     As shown in  FIG. 59 , the crown portion  1306  is generally thinner than the face portion  1308 . In many embodiments, the maximum transverse thickness of the crown portion T CMax  is thinner than the minimum transverse thickness of the face portion T FMin . For the purpose of gauging these thicknesses, the crown portion  1306  meets the face portion  1308  at the point of the transition where the outer surface has the tightest/smallest radius of curvature in a vertical plane. In the event of a portion of the transition having a constant radius of curvature across some segment of the outer surface, the point where they would meet should be regarded as the midpoint of the segment. In three dimensions, the crown portion meets the face portion at a line defined by the plurality of points taken from vertical cross-sectional slices. In some embodiments, the ratio of the average thickness of the crown portion T CAvg  to the average thickness of the face portion T FAvg  is between 1:2 and 1:3, 1:3 and 1:4, 1:4 and 1:5, 1:5 and 1:6, or 1:6 and 1:7. An inner surface of a transition region between the crown portion and the face portion may be smoothly rounded, configured with an angled chamfer, designed with one or more supporting features (such as ribs), and/or designed with one or more flex-enhancing features (such as slots or channels). This transition region may be regarded as the area surrounding the line where the crown portion meets the face portion. For example, the transition region may comprise the area defined by an offset of between about 2 mm and about 15 mm or between about 2 mm and about 10 mm or between about 2 mm and about 7 mm on either side of the dividing line. 
     Referring again to  FIG. 58 , the second component  1304  may generally include a sole portion  1310  and a hosel portion  1312 . In some embodiments, the sole portion  1310  may form a unitary bowl-like shape. The sole portion  1310  may wrap upwards into the heel to connect to the hosel portion  1312 . In some embodiments, the second component further comprises a boundary lip  1314  that wraps onto the front of the club head adjacent the sole, the heel, and the toe. This boundary lip  1314  may be configured to receive, overlap, and secure the face portion  1308  of the first component  1302 . The boundary lip  1314  may also wrap upwards to overlap or mate with an edge of the crown portion  1306  of the golf club head. In such an embodiment, the boundary lip  1314  may extend rearwards along an upper edge of the second component  1304  to provide an attachment surface for the first component  1302 . In one configuration, the boundary lip  1314  may form a lap joint interface, a tongue in groove interface, or even simply a recessed shelf that receives and secures the first component  1302 . Adhesives, co-molding chemical bonding, or other attachment mechanisms may likewise be employed at this interface to secure the first component  1302  to the second component  1304 . 
     In one configuration, the boundary lip  1314  may form a portion of the strikeface  30 . For example, instead of simply providing a joint surface against which the lower peripheral edge of the first component strikeface may be secured, the boundary lip  1314  may instead extend upward and form a portion of the strikeface  30 . In doing so, this boundary lip  1314  may operatively reinforce the polymeric face portion  1308 . In some embodiments, the boundary lip  1314  may extend across at least 25% of the strikeface  30 , or at least 50% of the strikeface  30 , or at least 60% of the strikeface  30 , or at least 70% of the strikeface  30 , or at least 80% of the strikeface  30 , or at least 90% of the strikeface, or across the entire strikeface  30 . This metallic strikeface backing (i.e., formed by the boundary lip  1314 ) may have a thickness that is substantially thinner than the thickness of a conventional metal-only strikeface. In some embodiments, the metal strikeface backing may have an average thickness of between about 0.4 mm and about 1.2 mm or between about 0.4 mm and about 0.8 mm and may be bonded to the first component, for example, using an adhesive or an interlocking surface texture/overmolding interface. 
     As noted above, the first component  1302  may generally have a polymeric composite structure. This structure maybe similar to one or more of the designs discussed above and may include a fabric reinforced composite layer  1320  and/or one or more filled thermoplastic layers  1322 . In one configuration, the first component  1302  may include a fabric reinforced layer  1320  that forms the outer surface  1324  of both the crown  18  and strikeface  30  (i.e., when the club head  1300  is fully assembled). To provide enhanced strength, particularly at the bend where the strikeface  30  meets the crown  18 , the fabric reinforced layer  1320  may include a plurality of constituent fibers that extend continuously from a rear edge  1326  of the crown  18  to a bottom edge  1328  of the strikeface  30 . 
     In some embodiments, the fabric reinforced layer  1320  (in this or any of the prior-mentioned embodiments) may comprise a plurality of discrete layers (i.e., plies) of unidirectional fabric that are stacked on each other to form a total thickness of the layer. Each unidirectional fabric ply may have an orientation that is expressed as the average longitudinal fiber direction/orientation of the fibers within that ply. In this construction, some of the plies should have an orientation that is nonparallel to plies that are directly adjacent (i.e., in a transverse/surface normal direction) layers. In the example shown in  FIGS. 58-59 , while some, or even a majority of the fibers may extend from a rear edge  1326  of the crown  18  to a bottom edge  1328  of the strikeface  30 , it is desirable for other fibers to be orthogonal to these fibers (i.e., 90 degree orientation), or provided at other angles relative to this primary orientation (e.g., −45, −30, 30 and/or 45 degrees). 
     In some embodiments, some or all of the first component  1302  may comprise a filled thermoplastic material that is formed through injection molding. For example, an injection molding process, such as generally illustrated in  FIG. 16 , may be adapted to the structure in  FIG. 59  to flow material across the face while also turning back toward the rear edge  1326  of the crown  18 . This structure may also be paired with a fabric reinforced composite layer, such as shown in  FIG. 12, 13 , or  18 , albeit with the overall geometry of  FIGS. 58-59 . 
       FIG. 60  schematically illustrates a method  1400  for constructing a polymeric composite structure for use in a golf club head. This method  1400  may be used to construct various laminate structures such as discussed with respect to  FIGS. 3-7, 9-13, 18, 20-31, 34-35, 39-47, 51-59 , above. In this method, one or more polymeric layers may be compression molded together to form a laminate structure that has specific weight or directionally oriented strength properties. While this method will be described with respect to thermoplastic composite polymers, similar laminate structures may also be formed using thermosetting polymers. It should be noted that for any formed component, it is strongly preferred for all polymeric resin within the component to be of the same type (i.e., thermoplastic vs. thermoset) to enable adequate interlayer bonding. Additionally, it is further preferred for all layers to utilize resins having a common type or formulations, as generally “like bonds with like,” whereas dissimilar polymers may have much weaker interlayer bonding. As such, in one embodiment, the composition of the resin in each layer is compounded to include a common polymer in an amount that is at least 40% by weight, or at least 60% by weight, or at least 80% by weight, or wherein each layer comprises an identical polymer resin composition in its entirety. 
     As generally shown in  FIG. 60 , the method  1400  generally begins at  1402  by providing a plurality of component layers that may be combined in a stacked arrangement through a compression molding operation to form a final composite laminate structure. As used herein, the action of “providing” may include forming, receiving, manufacturing, or otherwise making such layers available for subsequent manufacture. As generally illustrated, the plurality of component layers/plies may include a plurality fabric reinforced composite layers  1404 , and in some embodiments, may further include one or more of filled thermoplastic layers  1406 . 
     The fabric reinforced composite layers  1406  may each generally be formed by spreading (at  1408 ) a plurality of individual fibers such that they are all approximately parallel and co-planar. The spread fibers are then bound together in a resin matrix (at  1410 ) that is solidified or partially cured to form stock material. This stock material may then be die cut (at  1412 ) into a blank that is suitable to form or approximate the final component layer and optionally pre-molded (at  1414 ) into a shape that approximates the final contours of the component. 
     In one configuration, the filled thermoplastic layers  1406  may be formed by first injection molding a substantially uniform blank (at  1416 ) that has a regular shape and is designed to maximize the uniformity of discontinuous fiber orientation within the thermoplastic polymer resin. An example shape may be a bar where the mold is gated at a first longitudinal end and is vented at an opposite longitudinal end. From this stock, a component blank may be cut (at  1418 ) and optionally pre-molded (at  1420 ) into a shape that approximates the final contours of the component. 
     In general, the pre-molding steps  1414 ,  1420  may comprise, for example, vacuum forming, compression molding, and the like. In the case of thermoplastic resins, it may further require heating the component layer to a temperature above the glass transition temperature of the polymer prior to forming it on a mold. 
     With either component type (filled or fabric reinforced), the component may be cut from the stock such that the fiber direction is at a prescribed orientation relative to the component. In this manner, each constituent layer within the final structure may have an engineered primary strength dimension. 
     In still another configuration, instead of being injection molded into a stock material with uniform fiber orientation (i.e., and then cut from the stock material) the layer may be injection molded into a final or substantially final shape/geometry in a first instance (at  1422 ). In such a configuration, placement of gates, vents, flow leaders, and wells within the mold design may direct flow in such a manner to control fiber orientation in more complex ways (e.g., such as shown in  FIG. 16 ). Doing so may enable non-uniform fiber orientation that may, for example, arc/bend, converge, diverge/fan out, and the like. 
     Following the creation of the individual constituent layers, one or more of the layers may be pre-heated (at  1424 ) prior to the layers being stacked (at  1426 ) and placed in a mold (at  1428 ). The preheating step may be more applicable when using a thermoplastic resin to bring the temperature of the polymer up closer to the glass transition temperature. Such pre-heating may be accomplished, for example, using radiant and/or convective heating. With some thermosetting resins, the pre-heating step may be omitted as it may prematurely initiate cross-linking of the polymer. 
     Once in the mold, the plurality of layers may be fused together through the application of heat and pressure (at  1430 ) to create a unitary laminate structure. In some embodiments, the laminate structure may comprise one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, or twenty composite layers/sheets/plies. In other embodiments, the composite structure may contain between 20 and 40, or between 40 and 60 layers/sheets/plies. 
     In some embodiments, one or more layers may have a non-uniform thickness, or may extend across only a portion of the created component. For example, in the component illustrated in  FIG. 59 , the face portion  1308  may include more layers than the crown portion  1306 . More specifically, if created using a plurality of fabric reinforced layers, a first plurality of layers may include fibers that are oriented to extend from the bottom edge of the strike face to the rear edge of the crown (zero-degree plies). Then, both the crown portion  1306  and face portion  1308  may include additional layers/plies that are non-zero degree (i.e., oriented at a non-parallel angle relative to the zero-degree plies), however the face portion  1308  may contain more of these non-zero degree plies than the crown portion  1306 . Doing so may result in a face thickness that is greater than the crown thickness (i.e. due to the greater number of total plies), while also providing more lateral/horizontal strength across the face (i.e., in a heel-toe direction). In some embodiments, within a given transverse thickness, the laminate may comprise a plurality of fiber reinforced composite layers/plies and one or more filled thermoplastic layers. 
     In one embodiment, the reinforcing fibers in the fiber reinforced composite may specifically comprise a pitch-based carbon fiber, which has a higher modulus of elasticity than more commonly used polyacrylonitrile (PAN) carbon fibers. Further, in some embodiments, each pre compression molded layer of fabric reinforced composite may have a fiber areal weight (FAW) of less than about  15 g/m 2 , or less than about  g/m2 or less than about 7 g/m2, or between about 5 g/m 2  and about 20 g/m 2 , or between about 7 g/m 2  and about 15 g/m 2 , or between about 5 g/m 2  and about 10 g/m 2 , or about 7 g/m 2 . A prepreg with this FAW may typically involve a fabric having an average thickness that is approximately equal to between 1.0 and about 2.5 times the diameter of a single fiber. Such a prepreg is different than conventional fabric reinforced prepregs that have a FAW of between about 75 g/m 2  and about 150 g/m 2 , which may have a thickness that is at least 5-15 times the diameter of a single fiber. By using thinner pre-pregs, greater control of dimensional strength properties may be achieved while at the same time minimizing the ability for transverse cracks to propagate through the structure. In doing so, the desired design strength may be achieved via lighter and thinner overall structures. For example, in one embodiment, a pitch-based carbon fiber fabric reinforced crown portion, having a FAW of about 7 g/m 2  per layer, may achieve suitable design strength at an average thickness of about 0.007 inch (about 0.177 mm). 
     With general reference to any of the embodiments described above that include a fabric reinforced composite resilient layer, it should be appreciated that any of these layers may be constructed using the techniques described in  FIG. 60 . In some configurations, the resilient layer may be formed using these compression molding techniques separate from the creation or bonding of any structural layer. Said another way, the resilient layer may be a composite structure/laminate in its own right and may comprise a plurality of unidirectional fabric reinforced composite layers. In some configurations each layer may have a fiber areal weight (FAW) of less than about 15 g/m2, or less than about 10 g/m2 or less than about 7 g/m2, or between about 5 g/m 2  and about 20 g/m 2 , or between about 7 g/m 2  and about 15 g/m 2 , or between about 5 g/m 2  and about 10 g/m 2 , or about 7 g/m 2 . Further, to provide improved structural performance while reducing the ability for cracks/fractures to transversely propagate, directly adjacent layers of unidirectional fabric may be non-parallel. 
     As noted above, while the present designs may be formed using thermosetting polymeric resins, thermoplastic resins provide several distinct advantages. For example, thermoplastics provide easier and longer-term storage options for intermediate layers and stock inventory. Conversely, thermosetting prepregs have a finite shelf life due to tendency for the polymer chains to gradually cross-link. Also precured/partially cured thermosets tend to be mildly tacky, which may require more care when storing. Finally, thermoplastic resins may be more easily recycled, both in terms of manufacturing waste (e.g., defect parts, molding scrap, off cuts), and in terms of post-consumer waste. 
     Replacement of one or more claimed elements constitutes reconstruction and not repair. Additionally, benefits, other advantages, and solutions to problems have been described with regard to specific embodiments. The benefits, advantages, solutions to problems, and any element or elements that may cause any benefit, advantage, or solution to occur or become more pronounced, however, are not to be construed as critical, required, or essential features or elements of any or all of the claims, unless such benefits, advantages, solutions, or elements are expressly stated in such claims. 
     As the rules to golf may change from time to time (e.g., new regulations may be adopted or old rules may be eliminated or modified by golf standard organizations and/or governing bodies such as the United States Golf Association (USGA), the Royal and Ancient Golf Club of St. Andrews (R&amp;A), etc.), golf equipment related to the apparatus, methods, and articles of manufacture described herein may be conforming or non-conforming to the rules of golf at any particular time. Accordingly, golf equipment related to the apparatus, methods, and articles of manufacture described herein may be advertised, offered for sale, and/or sold as conforming or non-conforming golf equipment. The apparatus, methods, and articles of manufacture described herein are not limited in this regard. 
     While the above examples may be described in connection with an iron-type golf club, the apparatus, methods, and articles of manufacture described herein may be applicable to other types of golf club such as a driver wood-type golf club, a fairway wood-type golf club, a hybrid-type golf club, an iron-type golf club, a wedge-type golf club, or a putter-type golf club. 
     Moreover, embodiments and limitations disclosed herein are not dedicated to the public under the doctrine of dedication if the embodiments and/or limitations: (1) are not expressly claimed in the claims; and (2) are or are potentially equivalents of express elements and/or limitations in the claims under the doctrine of equivalents.