Patent Publication Number: US-11654339-B2

Title: Multi-material iron golf club head

Description:
CROSS-REFERENCES 
     This is a continuation of U.S. patent application Ser. No. 16/286,462, filed Feb. 26, 2019, which claims benefit of U.S. Provisional Patent Application No. 62/635,020, filed on Feb. 26, 2018; U.S. Provisional Patent Application No. 62/713,424, filed Aug. 1, 2018; and U.S. Provisional Patent Application No. 62/768,543, filed on Nov. 16, 2018, the contents of all of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to golf equipment, and more particularly, to a multi-material iron golf club head, and methods to manufacture said golf club head. 
     BACKGROUND 
     Typically, iron-type golf club heads comprise various styles, such as muscle-back, cavity-back, or tour irons. Golfers having a high skill level with a low handicap prefer to play compact and aesthetically sleek tour irons. Tour irons have a higher loft, lower center of gravity (hereafter “CG”), shorter length of shaft, a smaller profile, and a thinner top line. Tour irons generally have a sleek, classic look and a desirable sound. Forged tour irons are, in particular, thought to offer an improved “feel” over other types of irons, such as cast irons, and provide aesthetic sight lines. Generally, low handicap golfers, such as tour players, desire iron type club heads with the CG low and close to the face of the club. Tour irons allow these golfers to further shape their shots by manipulating the part of the club face that impacts the golf ball, because of a smaller sweet spot for straight flight. Although challenging for a high handicap golfer to use effectively, tour irons fill a niche demand for the highly skilled and often low handicap golfers. 
     On the other hand, game improvement irons are typically designed to cater to high handicap golfers who desire increased forgiveness and higher loft in their irons. High handicap golfers tend to play iron type club heads with a higher moment of inertia (MOI), which gives the club head more forgiveness. Game improvement irons, such as deep cavity back, muscle-back, or hollow-bodied irons, allow for perimeter weighting, which increases the forgiveness of the club head, and results in greater distance due to the face having room to bend. However, game improvement irons understandably “feel” less like a solid-bodied tour iron and can sound less pure to golfers who are accustomed to traditional solid irons. Game improvement irons have a large profile, resulting in a bulky feel. These game improvement irons can also have a thick top line and other shaping features that many golfers consider less aesthetically pleasing. The golf club head described herein caters to aspiring golfers who desire a club that shares the benefits of both game improvement and tour irons. 
     There is a need in the art for a club head having the compact size and solid feel and sound of traditional tour irons, without sacrificing the high moment of inertia and perimeter weighting of traditional game improvement irons, that can be used by mid-low handicap players. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a exploded perspective view of a golf club head according to an embodiment; 
         FIG.  2    shows a front view of the golf club head of  FIG.  1   ; 
         FIG.  3    shows a rear view of the golf club head of  FIG.  1   ; 
         FIG.  4    shows toe-side view of the golf club head of  FIG.  1   ; 
         FIG.  5    shows a cross-sectional toe-side view of the golf club head of  FIG.  1   , along the line V-V in  FIG.  3   ; 
         FIG.  6    shows a cross-sectional toe-side view of the golf club head of  FIG.  1   , along the line V-V in  FIG.  3   , according to an first embodiment with a multi-material insert; 
         FIG.  7    shows a cross-sectional toe-side view of the golf club head of  FIG.  1   , along the line V-V in  FIG.  3   , according to a second embodiment with a multi-material insert; 
         FIG.  8    shows a cross-sectional toe-side view of the golf club head of  FIG.  1   , along the line V-V in  FIG.  3   , according to a third embodiment with a multi-material insert; 
         FIG.  9    shows a cross-sectional toe-side view of the golf club head of  FIG.  1   , along the line V-V in  FIG.  3   , according to a fourth embodiment with a multi-material insert; 
         FIG.  10    shows a cross-sectional toe-side view of a golf club head, according to an embodiment having a rear shelf; 
         FIG.  11    shows a cross-sectional toe-side view of a golf club head, according to an embodiment having a rear shelf angled at 90 degrees from the loft plane; 
         FIG.  12    shows a cross-sectional toe-side view of the golf club head of  FIG.  1   , along the line V-V in  FIG.  3   , including a tape layer; 
         FIG.  13    shows a rear perspective view of the golf club head of  FIG.  1   , including an exploded view of the toe cavity and toe weight; 
         FIG.  14    shows an exploded view of a golf club head, according to a second embodiment; 
         FIG.  15    shows a rear view of the golf club head of  FIG.  14   ; 
         FIG.  16    shows a cross-sectional heel-side view of the golf club head of  FIG.  14   , along the line XVI-XVI in  FIG.  15   ; 
         FIG.  17    shows a front perspective view of the body of the golf club head of  FIG.  14   ; 
         FIG.  18    shows a rear perspective view of the golf club head of  FIG.  14   ; 
         FIG.  19    shows a cross-sectional heel-side view of the golf club head of  FIG.  14   , along the line XVI-XVI in  FIG.  15   ; 
         FIG.  20    shows a cross-sectional heel-side view of the golf club head of  FIG.  14   , along the line XVI-XVI in  FIG.  15   , according to a first embodiment with a partial-fill insert; 
         FIG.  21    shows a cross-sectional heel-side view of the golf club head of  FIG.  14   , along the line XVI-XVI in  FIG.  15   , according to a second embodiment with a partial-fill insert; 
         FIG.  22    shows a cross-sectional heel-side view of the golf club head of  FIG.  14   , along the line XVI-XVI in  FIG.  15   , according to a third embodiment with a partial-fill insert; 
         FIG.  23    shows a cross-sectional heel-side view of the golf club head of  FIG.  14   , along the line XVI-XVI in  FIG.  15   , according to a fourth embodiment with a partial-fill insert; 
         FIG.  24    shows a method of manufacturing the golf club head of  FIG.  1   ; and 
         FIG.  25    shows a method of manufacturing the golf club head of  FIG.  14   . 
     
    
    
     It is well understood by those familiar with golf that tour irons are visibly distinct from game-improvement irons by both their size and appearance. Accordingly, tour irons comprise design requirements different than game-improvement irons. The golf clubs described herein satisfy a market demand for tour style irons while retaining the functional benefits of game-improvement irons. 
     Specifically, the golf club head described herein shares the aesthetically appealing features of tour irons (e.g. compact size, forged, solid feel), and the performance advantages of game-improvement irons (e.g. perimeter weighting and high forgiveness). Described herein is a golf club head having a body that forms a cavity, wherein an insert can fit within the cavity, and the cavity is enclosed either by a cap in the rear of the body or by a faceplate of the body. Accordingly, the golf club head provides a golfer with iron clubs having a tour style while retaining a level of forgiveness necessary for an intermediate or beginner skill golfer to make the most accurate shots possible for their skill level. Generally, tour irons are designed for highly skilled golfers or low handicap to mid handicap players, while game-improvement irons are designed for low to intermediate skill level golfers also having higher handicaps (over 10). The golf club head described herein provides an option for the golfer who desires to play with a set of tour irons lacking the skills to use traditional tour irons. 
     Additionally, the golf club head provides an option for the highly skilled golfer who desires to increase the accuracy of their shots through a high-MOI design. Although the golf club head described herein can comprise a MOI that is lower than certain game-improvement or standard irons, the club head nonetheless comprises an MOI that is higher than other golf club heads within the same category, namely tour or small profile irons. Furthermore, the disclosed golf club head provides a low CG that is desirable for high skill golfers. The golf club head described herein can be exemplified by, but not limited to, these embodiments. 
     The golf club head can be manufactured by methods that include swedging (swagging) the faceplate onto the body of the golf club head. A boundary between the faceplate and the body after swedging can be laser welded in a surface fusions treatment process. The insert is not damaged by the swedging or laser welding. 
     For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the present disclosure. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present disclosure. The same reference numerals in different figures denote the same elements. 
     DETAILED DESCRIPTION 
     Described herein is a golf club having a hollow golf club head, or partially/nearly hollow golf club head, each of which comprise a low-density insert (The hollow golf club head or partially/nearly hollow golf club head is hereafter referred to as “golf club head.”). The golf club has a golf club head, a shaft, and a grip. The golf club head comprises a body having a hosel, a front, a rear, a top rail, and a sole. The body can comprise a cavity. The faceplate, the sole, the rear and the top rail enclose a cavity. In some embodiments, the cavity of the golf club head can be enclosed from the front by the faceplate. In some embodiments, the cavity can open at the rear of the club, partially exposing the cavity. An insert can fit within the cavity. The front of the golf club head can further comprise a faceplate, which encloses the cavity from the front. 
     One embodiment of the golf club head described herein includes a body that forms a cavity and a low-density insert, wherein the cavity opens towards the front of the golf club head. The body has an internal cavity formed in the center of the club head. The body can be cast or forged. The cavity can receive and harbor the low-density insert. 
     The golf club head has a low-density center, a high-density perimeter, and, as mentioned above, a low-density insert to move weight to the perimeter thereby improving overall foregiveness. The insert comprises a low-density material, such as aluminum, titanium, or a composite. Filling the cavity with a solid insert improves the acoustics and the feel of the golf club head over other similar hollow-bodied irons. In some embodiments, adhesives and/or tape are used to further secure the insert into the cavity and to prevent rattling. 
     The faceplate encloses the front opening of the golf club head and forms the cavity. Swedging, press-fitting, and other low-temperature methods are used for securing the faceplate. TIG welding is not used. In some embodiments, the faceplate can be further secured to the body by laser welding, because laser welding is very precise and does not create a large heat-affected zone (hereafter “HAZ”) to affect the insert, tape, and/or adhesives. If the faceplate is TIG welded onto the front of the golf club head body, the insert, tape, and/or adhesives are exposed to high temperatures and are damaged, thereby corrupting the weight distribution of the insert and corrupting the material properties of the tape and/or adhesives. 
     A high-density perimeter of the golf club head can be also accomplished by a toe weight and/or a tip weight in the hosel. In some embodiments, the body can further comprise a toe cavity. A toe weight can be mounted within the toe cavity. The toe weight comprises a high-density material, such as tungsten. Additionally, in some embodiments, the golf club head can include a toe screw weight for swing weighting. 
     In a second embodiment of the golf club head, the cavity of the body is exposed via an opening in the upper portion of the rear. Similar to the first embodiment, the golf club head of the second embodiment comprises a body and a low-density insert. The body can be cast or forged. The body comprises a rear opening in an upper portion of the body. The low-density insert is housed in the cavity of the body. In this embodiment, the insert comprises a material that can be injected into the cavity, such as a thermoplastic composite, foam, or other filler damping material. 
     The golf club head further comprises a faceplate that forms a front boundary of the cavity. An injection molding process can form the low-density insert within the cavity of the body. The golf club head can further include a toe weight in a toe cavity of the body and/or a tip weight in the hosel for perimeter weighting. Additionally, the golf club head can include a toe screw weight for swing weighting. 
     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 “front,” “back,” “rear,” “top,” “bottom,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing 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 term “couple” and similar terms should be broadly understood and refer to connecting two or more elements, mechanically and/or otherwise. For example, two or more mechanical elements may be mechanically coupled, but not be electrically or otherwise coupled. Coupling may be for any length of time, e.g., permanent or semi-permanent or only for an instant. 
     The term MOI as described herein can be a quantity expressing a body&#39;s tendency to resist angular acceleration. MOI is also known as angular mass or rotational inertia. MOI determines the torque needed to achieve a desired angular acceleration about a rotational axis. A higher MOI gives a club head more forgiveness, meaning the golfer will notice more consistent shots even when the golf ball is struck with a portion of the strike-face that is off-center. MOI is raised by moving weight away from the center of the golf club head and towards the perimeter of the golf club head. In order to preserve a desirable overall golf club head weight, to increase MOI, the center of a golf club head must comprise either a cavity or a lighter material than the main golf club head. 
     The aspects of the golf club described herein may be applied to one or more golf clubs within a set of irons. In some embodiments, the set of irons comprises irons having varying club head size, shaft length, lie angle, loft angle, head weight, and/or other parameters. Each club head in the set of irons can be numbered according to convention with numbers ranging from 1 to 10. Most commonly a set is numbered from 3 to 9. Furthermore, the set of irons can comprise one or more wedges, which have a loft angle higher than the numbered irons. 
     In some embodiments, the golf club head can be a wedge. In many embodiments, the loft angle of the golf club head is less than approximately 50 degrees, less than approximately 49 degrees, less than approximately 48 degrees, less than approximately 47 degrees, less than approximately 46 degrees, less than approximately 45 degrees, less than approximately 44 degrees, less than approximately 43 degrees, less than approximately 42 degrees, less than approximately 41 degrees, or less than approximately 40 degrees. Further, in many embodiments, the loft angle of the golf club head is greater than approximately 16 degrees, greater than approximately 17 degrees, greater than approximately 18 degrees, greater than approximately 19 degrees, greater than approximately 20 degrees, greater than approximately 21 degrees, greater than approximately 22 degrees, greater than approximately 23 degrees, greater than approximately 24 degrees, or greater than approximately 25 degrees. 
     In many embodiments, the loft angle of the golf club head is less than approximately 64 degrees, less than approximately 63 degrees, less than approximately 62 degrees, less than approximately 61 degrees, less than approximately 60 degrees, less than approximately 59 degrees, less than approximately 58 degrees, less than approximately 57 degrees, less than approximately 56 degrees, less than approximately 55 degrees, or less than approximately 54 degrees. Further, in many embodiments, the loft angle of the golf club head is greater than approximately 46 degrees, greater than approximately 47 degrees, greater than approximately 48 degrees, greater than approximately 49 degrees, greater than approximately 50 degrees, greater than approximately 51 degrees, or greater than approximately 52 degrees. 
     In many embodiments, the golf club head can comprise a total volume of between 1.9 cubic inches and 2.7 cubic inches. In some embodiments, the total volume of the golf club head can be between 1.9 cubic inches and 2.4 cubic inches, 2.0 cubic inches and 2.5 cubic inches, 2.1 cubic inches and 2.6 cubic inches, 2.2 cubic inches and 2.7 cubic inches, 2.3 cubic inches and 2.7 cubic inches, or 2.4 cubic inches and 2.7 cubic inches. In other embodiments, the total volume of the golf club head  100  can be 1.9 cubic inches, 2.0 cubic inches, 2.1 cubic inches, 2.2 cubic inches, 2.3 cubic inches, 2.4 cubic inches, 2.5 cubic inches, 2.6 cubic inches, or 2.7 cubic inches. 
     In many embodiments, the golf club head can comprise a total mass of between 200 grams and 300 grams. In some embodiments, the golf club head can comprise a total mass of between 200 grams and 210 grams, 210 grams and 220 grams, 220 grams and 230 grams, 230 grams and 240 grams, 240 grams and 250 grams, 250 grams and 260 grams, 255 grams and 260 grams, 260 grams to 270 grams, 265 grams to 275 grams, 270 grams and 280 grams, 275 grams and 280 grams, or 250 grams and 270 grams. In other embodiments, the total mass can be 200 grams, 205 grams, 210 grams, 220 grams, 225 grams, 230 grams, 235 grams, 240 grams, 245 grams, 250 grams, 255 grams, 260 grams, 265 grams, 270 grams, 275 grams, 280 grams, 285 grams, 290 grams, 295 grams, or 300 grams. 
     The golf club head described herein can be viewed from various perspectives, while in address position, including but not limited to: a front view, a rear view, a toe-side view, a heel-side view, a top view, a sole view, and various perspective views. For example, the front view of the golf club head  100 , views the club head from a direction forward of the loft plane  20 , parallel to the ground plane  10 . The rear view of the golf club head  100  views the club head from a direction rearward of the rear  103 , parallel to the ground plane  10 . The toe-side view of the golf club head  100  views the club head from a toe-to-heel direction that is parallel to the ground plane  10 . The heel-side view of the golf club head  100  views the club head from a heel-to-toe direction that parallel to the ground plane  10 . The sole view of the golf club head  100  views the club head from a sole-to-top direction orthogonal to the ground plane  10 . The top view of the golf club head  100  views the club head from a top-to-sole direction orthogonal to the ground plane  10 . 
     I. Golf Club Head with Insert and Enclosing Faceplate 
     Described herein is a golf club head  100 . The golf club head  100  can be a tour style golf club head with forgiveness as discussed above. The golf club head  100  can comprises a body having a cavity that houses an insert. The golf club head comprises a faceplate, a body, and an insert. The body comprises an upper portion, a lower portion, a sole, a rear, and a top rail. The rear can further comprise an inflection seam. The inflection seam is the boundary between the upper portion and lower portion of the golf club head. The faceplate and a portion of the body define a striking surface of the golf club head. The faceplate, the sole, the rear, and the top rail enclose a cavity. 
     The cavity of the body opens towards the front of the golf club head and is enclosed by a faceplate. The faceplate can be swedged and laser welded to the body. The club head is a tour iron club head, and has a volume between 1.8 cubic inches and 2.7 cubic inches (30 cubic centimeters (cc) and 45 cc). The body of the golf club head can be cast or forged from a metal material. 
     The insert comprises a low-density material and fills the cavity formed by the body of the golf club head. Reducing mass in the center of the golf club head allows extra mass to be concentrated at its perimeter to increase moment of inertia values of the golf club head. As discussed above, the golf club head comprises a lower portion and an upper portion. The lower portion comprises a depth greater than the upper portion. The lower portion thereby has more mass concentrated on the peripheral heel end, toe end, and the sole. Lowering the mass of the body results in a low CG, which increases launch angle and reduces spin. As introduced above, there is a need in the art for an iron that couples tour iron sizing with a comparatively high moment of inertia from perimeter weighting and a low CG from low positioning of mass. In some embodiments, a tip weight positioned in the hosel and/or a toe weight positioned in a toe cavity of the body provide additional perimeter weighting. 
     A. Parts of the Golf Club Head 
     Turning to  FIGS.  1 - 13   , the golf club head  100  comprises a faceplate  155 , a body  110 , and an insert  140  as discussed above. The body  110  may further comprise an upper portion  108 , a lower portion  109 , a sole  107 , a rear  103 , a toe side  101 , a heel side  102 , and a top rail  106 . The faceplate  155  and a portion of the body may define a strikeface  111 . The faceplate  155 , the sole  107 , the rear  103 , and the top rail  106  enclose a cavity  120 . The upper portion  108  is bounded by the top rail  106 . The lower portion  109  is bounded by the sole  107 . The rear  103  may comprise an inflection seam  130 . The inflection seam  130  can stretch from the toe side  101  to the heel side  102  of the golf club head. The inflection seam  130  bounds the upper portion  108  to the top rail  106 . The inflection seam  130  bounds the lower portion  109  to the sole  107 . The inflection seam  130  marks the end of a uniform upper portion depth  116 , as described below. As shown in  FIGS.  4 - 12   , the inflection seam  130  is depicted as an inflection point in any cross-sectional view taken in a top rail-to-sole direction from the toe-side view. 
     As illustrated in  FIGS.  2  and  3   , a ground plane  10  provides a reference for the ground when the golf club is at address position. As illustrated in  FIG.  4   , a face plane  20  is parallel to the strikeface  111 . As illustrated in  FIG.  2   , a centerplane  45  is perpendicular to the loft plane  20 , and coincident with a centerpoint  80  of the strikeface  111 . As shown in  FIGS.  2  and  4   , the golf club head  100  can have a coordinate system centered around the CG  60  of the golf club head  100 . Golf club heads  200  and  300 , described below, can have similar coordinate axes. An x-axis  30  reference axis extends in a toe-to-heel direction and through the CG  60 . The x-axis  30  is parallel with the strikeface. A y-axis  40  reference axis extends in a top rail-to-sole direction and through the CG  60 . The y-axis  40  is orthogonal to the ground plane  10  when the golf club head  100  is at address position. A z-axis  50  reference axis extends in a front-to-rear direction and through the CG  60 . The z-axis  50  is parallel to the ground plane  10  and perpendicular to the x-axis  30  and the y-axis  40 . Furthermore, a hosel axis  70  reference axis extends through the concentric center of the hosel  105 . A lead edge axis  35  is parallel to the ground plane  10 , extends in a heel-to-toe direction, and is coincident with a point that is lowest on the generally planar strikeface  111  along the center of the strikeface  111 . A lead edge plane is coincident with the lead edge axis  35  and parallel to the ground plane  10 . 
     1) Upper and Lower Portion of the Golf Club Head 
     As illustrated in  FIGS.  4  and  5   , the golf club head  100  comprises the upper portion  108  and the lower portion  109 . As discussed above, the upper portion  108  can be separated from the lower portion  109  by the inflection seam  130 . The upper portion  108  of the rear  103  of the body can comprise an uniform depth  116 . The rear  103  comprises an upper wall  131  and a lower wall  132 . By staying substantially parallel to the loft plane  20 , the upper wall of the rear  103  enables a constant depth  116  in the upper portion  108  of the golf club head  100 . At the inflection seam  130 , the rear contour transitions between the upper portion  108  and the lower portion  109  of the golf club head  100 , causing a shift in the depth of the golf club head  100 . This change in depth leads to the lower portion  109  having a greater depth  118  than the upper portion  108 , as described below. The greater depth of the lower portion  109  is beneficial for lowering the CG of the golf club head  100  and improving launch characteristics. 
     This contour of the rear  103  of the golf club head  100  enables mass to be placed lower in the golf club head  100  than in golf club heads with a flat rear design. By moving mass lower in the club head, the CG is lowered. This allows for improved ball launch and spin characteristics of the golf ball when impact by the golf club head  100 . The full benefits of the CG location are best understood by way of comparison to a golf club head with a flat rear, as provided below in Example 3. In some embodiments, the golf club head  100  can comprise a CG that is lower than the CG of a flat back comparison golf club head by between 0.030 inch and 0.050 inch. In some embodiments, the CG is lowered by between 0.030 inch and 0.032 inch, 0.032 inch and 0.034 inch, 0.034 inch and 0.036 inch, 0.036 inch and 0.038 inch, 0.038 inch and 0.040 inch, 0.040 inch and 0.042 inch, 0.042 inch and 0.044 inch, 0.044 inch and 0.046 inch, 0.046 inch and 0.048 inch, or 0.048 inch and 0.050 inch. 
     The rear contour can vary between embodiments in order to allow the upper portion  108  and the lower portion  109  to have different depths, volumes, or masses. As shown in the cross sections of  FIGS.  10  and  11   , in some embodiments, the lower wall  132  of the rear  103  can comprise a shelf  139  just below the inflection seam  130 . The shelf  139  can be between the upper wall  131  and the remainder of the lower wall  132 . In these embodiments, the shelf  139  extends backwards and/or downwards from the inflection seam  130 . In some embodiments, such as the one illustrated in  FIG.  11   , the shelf  139  is approximately perpendicular to the loft plane  20 . By varying the rear contour, the depths, volumes, or masses of the upper and lower portions  108 ,  109  can be altered, which affects the location of the CG and the value of the MOI. 
     2) Heights of the Upper Portion and Lower Portion 
     As illustrated in  FIGS.  4  and  5   , the golf club head  100  comprises the upper portion  108  and the lower portion  109 , which are divided by the inflection seam  130 . The upper portion  108  comprises a height  188  measured along the centerplane  45  from the top rail  106  to the inflection seam  130 , in a direction parallel to the loft plane  20 . The upper portion height  188  can be between 0.60 inch and 0.90 inch. In some embodiments, the upper portion height  188  can be between 0.60 inch and 0.65 inch, 0.65 inch and 0.70 inch, 0.70 inch and 0.75 inch, 0.75 inch and 0.80 inch, 0.80 inch and 0.85 inch, 0.085 inch and 0.90 inch, 0.60 inch and 0.70 inch, 0.70 inch and 0.80 inch, or 0.80 inch and 0.90 inch. 
     The lower portion  109  comprises a height  189  measured along the centerplane  45  from the top rail  106  to the inflection seam  130 , in a direction parallel to the loft plane  20 . The lower portion height  189  can be between 0.80 inch and 1.10 inch. In some embodiments, the lower portion height  189  can be between 0.80 inch and 0.85 inch, 0.85 inch and 0.90 inch, 0.90 inch and 0.95 inch, 0.95 inch and 1.0 inch, 1.0 inch and 1.05 inch, 1.05 inch and 1.10 inch, 0.9 inch and 1.0 inch, or 1.0 inch and 1.1 inch. 
     A ratio of the upper portion height  188  and the lower portion height  189  can be between 9:8 (54:48) and 6:11 (54:99). In some embodiments, the ratio of the upper portion height  188  and the lower portion height  189  can be between 9:8 (54:48) and 6:8 (54:72), 6:8 (54:72) and 9:11 (54:66), or 9:11 (54:66) and 6:11 (54:99). A higher ratio of the upper and lower portion heights  188 ,  189  can result in a lower CG because the lower portion  109  comprises a greater depth and mass, as described below. A low CG improves launch and spin characteristics by reducing the torque imparted to the golf club head  100  upon impact with a golf ball. A low CG can also increase the ball speed and improve the feel of the golf club head  100 . 
     3) Depths of the Upper Portion and Lower Portion of the Golf Club Head 
     As illustrated in  FIGS.  4  and  5   , the upper portion  108  of the golf club head  100  can comprise a uniform depth. The upper portion depth  116  of club head  100  can be between 0.200 inch and 0.250 inch. In some embodiments, the upper portion depth  116  can be between 0.200 inch and 0.210 inch, 0.205 inch and 0.215 inch, 0.210 inch and 0.220 inch, 0.215 inch and 0.225 inch, 0.220 inch and 0.230 inch, 0.225 inch and 0.235 inch, 0.230 inch and 0.240 inch, 0.235 inch and 0.245 inch, 0.240 inch and 0.250 inch, or 0.245 inch and 0.250 inch. 
     The lower portion  109  comprises a depth  118  measured perpendicular to the loft plane  20  from the strikeface  111  to an outer surface of the rear  103 , along the centerplane  45 . The lower portion depth  118  can vary in a top rail-to-sole direction and/or in a heel-to-toe direction. The lower portion depth  118  is equal or greater in depth than the depth of the upper portion  116  of the golf club head  100 . The lower portion depth  118  can be between 0.270 inch and 0.780 inch. In other embodiments, the lower portion depth  118  can be between 0.270 inch and 0.320 inch, 0.320 inch and 0.380 inch, 0.380 inch and 0.430 inch, 0.430 inch and 0.480 inch, 0.480 inch and 0.530 inch, 0.530 inch and 0.580 inch, 0.580 inch and 0.630 inch, 0.630 inch and 0.680 inch, 0.680 inch and 0.730 inch, 0.730 inch and 0.780 inch, 0.270 inch and 0.470 inch, 0.320 inch and 0.520 inch, 0.370 inch and 0.570 inch, 0.420 inch and 0.620 inch, 0.470 inch and 0.670 inch, 0.420 inch and 0.620 inch, 0.470 inch and 0.670 inch, 0.520 inch and 0.720 inch, or 0.570 inch and 0.770 inch. 
     In the toe  101  and the heel  102  of the club head  100 , the lower portion depth  118  can differ from the lower portion depth  118  at the centerplane  45 . A minimum lower portion depth  118  in the toe  101  can be between 0.300 inch and 0.460 inch. In other embodiments, the lower portion depth  118  in the toe region  101  can be between 0.300 inch and 0.320 inch, 0.320 inch and 0.330 inch, 0.330 inch and 0.340 inch, 0.340 inch and 0.360 inch, 0.360 inch and 0.380 inch, 0.380 inch and 0.400 inch, 0.400 inch and 0.420 inch, 0.420 inch and 0.440 inch, or 0.440 inch and 0.460 inch. 
     The lower portion depth  118  at the heel  102  can differ from the lower portion depth at the centerplane  45  as well. A minimum lower portion depth  118  in the heel region  102  can be between 0.270 inch and 0.315 inch. In other embodiments, the lower portion depth  118  in the heel region  102  can be between 0.270 inch and 0.280 inch, 0.280 inch and 0.290 inch, 0.290 inch and 0.300 inch, 0.300 inch and 0.310 inch, 0.310 inch and 0.320 inch, 0.320 inch and 0.340 inch, 0.340 inch and 0.360 inch, 0.360 inch and 0.380 inch, 0.380 inch and 0.400 inch, 0.400 inch and 0.420 inch, 0.420 inch and 0.440 inch, or 0.440 inch and 0.460 inch. 
     A maximum depth of the club head  100  is located within the lower portion  109  of the body  110 . The maximum of depth of the club head  100  is measured perpendicular to the loft plane  20  from the strikeface  111  to an outer surface of the rear  103 . The maximum depth can be between 0.670 inch to 0.770 inch. In other embodiments, the maximum depth can be between 0.670 inch to 0.690 inch, 0.690 inch and 0.710 inch, 0.710 inch and 0.730 inch, 0.730 inch and 0.750 inch, or 0.750 inch and 0.770 inch. 
     In some embodiments, a ratio between the upper portion depth  116  and the lower portion depth  118  can be between 1:3 and 4:5. In some embodiments, the ratio between the upper  116  and lower  118  depths can be between 1:3 and 1:2, between 1:2 and 2:3, or between 2:3 and 4:5. 
     4) Volume of the Upper Portion and Lower Portion of the Golf Club Head 
     Referring to  FIGS.  4  and  5   , the upper and lower portions  108 ,  109  of the golf club head  100  can comprise a volume. The volume is measured from a plane adjacent the heel  102  and coincident with an edge/periphery of the faceplate  155  to the toe  101 . The volume of the upper portion  108  can be between 0.20 cubic inches and 0.60 cubic inches. In some embodiments, the volume of the upper portion  108  can be between 0.20 cubic inches and 0.30 cubic inches, 0.25 cubic inches and 0.35 cubic inches, 0.30 cubic inches and 0.40 cubic inches, 0.35 cubic inches and 0.45 cubic inches, 0.40 cubic inches and 0.50 cubic inches, 0.45 cubic inches and 0.55 cubic inches, or 0.50 cubic inches and 0.60 cubic inches. In some embodiments, the volume of the upper portion  108  is 0.48 cubic inches. 
     As illustrated in  FIG.  5   , the upper portion  108  and the lower portion  109  together form the body  110 , which defines the cavity  120 . A portion of the cavity  120  within the upper portion  108  of the body  110  can have a volume between 0.05 cubic inches and 0.40 cubic inches (0.82 cc and 6.55 cc). In some embodiments, the cavity volume in the upper portion  108  can be between 0.05 cubic inches and 0.15 cubic inches, 0.10 cubic inches and 0.20 cubic inches, 0.15 cubic inches and 0.25 cubic inches, 0.20 cubic inches and 0.30 cubic inches, 0.25 cubic inches and 0.35 cubic inches, 0.30 cubic inches and 0.40 cubic inches, or 0.35 cubic inches and 0.45 cubic inches. In some embodiments, the cavity volume in the upper portion  108  is 0.17 cubic inches. 
     To properly place the CG low within the golf club head  100 , the golf club head  100  below the inflection seam  130  (i.e. the lower portion  109 ), is larger in volume than the golf club head  100  above the infection seam  130  (i.e. the upper portion  108 ). The volume of the lower portion  109  of the club head  100  is measured the same as the upper portion  108  (i.e., measured from a plane adjacent the heel  102  and coincident with an edge/periphery of the faceplate  155  to the toe) The volume of the lower portion  109  can be between 1.15 cubic inches and 1.55 cubic inches. In some embodiments, the volume of the lower portion  109  can be between 1.15 cubic inches and 1.35 cubic inches, 1.25 cubic inches and 1.45 cubic inches, 1.35 cubic inches and 1.55 cubic inches, 1.20 cubic inches and 1.30 cubic inches, 1.30 cubic inches and 1.40 cubic inches, or 1.40 cubic inches and 1.50 cubic inches. In some embodiments, the volume of the upper portion is 1.36 cubic inches. 
     A portion of the cavity  120  within the lower portion  109  can have a volume between 0.15 cubic inches and 0.60 cubic inches (2.46 cc and 9.83 cc). In some embodiments, the cavity volume in the lower portion  109  can be between 0.15 cubic inches and 0.25 cubic inches, 0.20 cubic inches and 0.30 cubic inches, 0.25 cubic inches and 0.35 cubic inches, 0.30 cubic inches and 0.40 cubic inches, 0.35 cubic inches and 0.45 cubic inches, 0.40 cubic inches and 0.50 cubic inches, 0.45 cubic inches and 0.55 cubic inches, or 0.50 cubic inches and 0.60 cubic inches. In some embodiments, the cavity volume in the lower portion  109  is 0.37 cubic inches. 
     5) Overall Volume of the Cavity 
     Referring back to  FIG.  1   , the golf club head  100  can comprise the body  110  comprising a cavity  120  in a central portion of the golf club head  100 . The cavity  120  is filled with the low-density insert  140 , which increases the forgiveness of the golf club head  100  without sacrificing the solid feel and look of a tour iron. The forgiveness of the golf club head  100  corresponds to the amount of perimeter weighting, which is affected by the volume of the cavity  120 . A larger cavity eliminates more mass from a central region of the golf club head  100  than a smaller cavity. Consequently, a larger cavity allows more weight to be positioned on the perimeter of the golf club head  100 . 
     The cavity  120  can have a volume between 0.2 cubic inches and 0.8 cubic inches (3.28 cc and 13.11 cc). In some embodiments, the cavity  120  volume can be between 0.2 cubic inches and 0.3 cubic inches, 0.2 cubic inches and 0.25 cubic inches, 0.25 cubic inches and 0.30 cubic inches, 0.30 cubic inches and 0.40 cubic inches, 0.30 cubic inches and 0.35 cubic inches, 0.35 cubic inches and 0.40 cubic inches, 0.40 cubic inches and 0.50 cubic inches, 0.40 cubic inches and 0.45 cubic inches, 0.45 cubic inches and 0.50 cubic inches, 0.50 cubic inches and 0.60 cubic inches, 0.50 cubic inches and 0.55 cubic inches, 0.55 cubic inches and 0.60 cubic inches, 0.60 cubic inches and 0.70 cubic inches, 0.60 cubic inches and 0.65 cubic inches, 0.65 cubic inches and 0.70 cubic inches, 0.70 cubic inches and 0.80 cubic inches, 0.70 cubic inches and 0.75 cubic inches, 0.75 cubic inches and 0.80 cubic inches. In other embodiments, the cavity  120  can have a volume of 0.20 cubic inch, 0.22 cubic inch, 0.24 cubic inch, 0.26 cubic inch, 0.28 cubic inch, 0.30 cubic inch, 0.32 cubic inch, 0.34 cubic inch, 0.36 cubic inch, 0.38 cubic inch, 0.40 cubic inch, 0.42 cubic inch, 0.44 cubic inch, 0.46 cubic inch, 0.48 cubic inch, 0.50 cubic inch, 0.52 cubic inch, 0.54 cubic inch, 0.56 cubic inch, 0.58 cubic inch, 0.60 cubic inch, 0.62 cubic inch, 0.64 cubic inch, 0.66 cubic inch, 0.68 cubic inch, 0.70 cubic inch, 0.72 cubic inch, 0.74 cubic inch, 0.76 cubic inch, 0.78 cubic inch, or 0.80 cubic inch. 
     The cavity  120  can have a volume that is between 5% and 60% of the total club head volume, described above. In some embodiments, the cavity  120  can have a volume that is between 5% and 10%, 10% and 30%, 15% and 35%, 20% and 40%, 25% and 45%, 30% and 50%, 35% and 55%, or 40% and 60% of the total club head volume. In one embodiment, the volume of the cavity  120  is between 17% and 32% of the club head volume. 
     Increasing the volume of the cavity  120  results in the elimination of weight from the central region of body  110 . This saved weight can be redistributed around the perimeter of the golf club head  100  to give the golf club head  100  greater forgiveness. 
     The heights, depths, and volumes of the upper and lower portions  108 ,  109  of the body  110  provide the club head  100  with a low-positioned CG  60 . Therefore, the golf club head  100  comprises a lower CG than a golf club head having a flat rear, as exemplified in Example 3 below. As described above, the golf club head  100  can comprise a CG  60  that is lower than the CG of a flat back comparison golf club head by between 0.030 inch and 0.050 inch. The lower CG  60  causes the golf club head  100  to have better launch characteristics, better spin characteristics, and higher ball speed than a flat back golf club head. 
     6) Thickness Profiles of the Golf Club Head 
     The thickness of the rear  103  of the body  110  also affects the weighting and thereby the CG location of the golf club head  100 . The thickness is measured from an exterior surface of the rear  103  to an interior surface of the rear  103  within the cavity  120 . In some embodiments, the rear  103  of the body  110  is thicker adjacent the sole  107  of the body  110 . Due to the density of the body  110  material, the greater thickness adjacent the sole  107  moves mass downward compared to a golf club head body having a uniform rear thickness. As illustrated in the cross-section of  FIG.  5   , the rear  103  of the body  110  can have a thickness  113 . The rear thickness  113  can range between 0.030 inch and 0.100 inch. In some embodiments, the thickness  113  can be 0.030 inch, 0.040 inch, 0.050 inch, 0.060 inch, 0.070 inch, 0.080 inch, 0.090 inch, or 0.100 inch. The rear thickness  113  can be constant across the rear  103 . In some embodiments, the rear thickness  113  varies across the rear  103  in a heel-to-toe direction and/or in a top rail-to-sole direction. Varying the thickness  113  of the rear  103  can assist in moving mass towards the sole  107  and rear  103  of the golf club head  100 . Shifting the mass towards the sole  107  and rear  103  lowers the CG, which improves launch characteristics, improves spin characteristics, and increases ball speed. 
     7) Cavity of the Body 
     As illustrated in  FIGS.  1  and  5   , body  110  can comprise an internal peripheral edge  127  that defines the cavity  120  outer boundaries. The internal peripheral edge  127  circumscribes the cavity  120 . The peripheral edge  127  internally bounds the top rail  106 , sole  107 , toe  101 , and heel  102 . The internal peripheral edge  127  can follow the contours of the external edge of the golf club head  100 . Because the peripheral edge  127  of the cavity  120  extends as close to the edges of the golf club head  100  as possible, the size of the cavity  120  is maximized. Consequently, the size of the low-density insert  140  and its weighting benefits are also maximized. 
     In some embodiments, not depicted, the peripheral edge  127  gently tapers so that in a cross-section of the golf club head  100 , taken in a front-to-rear direction, the cavity  120  covers a larger area closer to the front  104  and smaller area closer to the rear  103 . In these embodiments, this tapered geometry enables the larger area adjacent the front  104  to harbor more surface area of the low-density insert thereby placing it closer to the front  104 . Less internal cavity area is left for the low density insert and more of the high density material is left in the rear  103  of the golf club head  100 . Thus, the shaping of the cavity  120  can enable the placement of more mass adjacent the rear  103  and sole  107  of the golf club head  100 , shifting the CG down and back. 
     8) Indentation in the Cavity of the Golf Club Head 
     As shown in  FIGS.  1  and  5   , the front  104  of the body  110  further comprises an indentation  142  for receiving the faceplate  155 . The indentation  142  connects to a front opening of the cavity  120 , but is not considered part of the cavity  120 . The indentation  142  comprises a peripheral edge  143  that generally follows the contours of the golf club head  100 , including, but not limited to, the top rail  106 , an edge of the body within the toe  101 , the sole  107 , and a roughly vertical dividing line adjacent the heel  102 . The peripheral edge  143  of the indentation  142  is offset from the internal peripheral edge  127  that defines the cavity  120 . The footprint of the indentation  142 , as bounded by the peripheral edge  143 , is larger than the area circumscribed by the internal peripheral edge  127  at a front of the cavity  120 . The indentation  142  has a depth approximately equivalent to the thickness of the faceplate  155 , described below. 
     The faceplate  155  aligns with the indentation  142  and sits within the cavity  120  and is seated on the indentation  142 . The insert  140  (as described below) fits within the cavity to a volume that is flush with the indentation  142 . The remaining volume of the cavity  120  is filled by the faceplate  155  that seats on the indentation  142 . Together, the insert  140  and the faceplate  155  fill the entire volume of the cavity  120  and the indentation  142  of the golf club head  100 . The insert  140  does not cover the indentation  142 , but rather sits flush with the indentation  142 . Thereby, the insert  140  does not interfere with the faceplate  155  seating on the indentation  142 . 
     In other embodiments as described below, the insert  140  does not fill the volume of the cavity  120  to the indentation  142 , but only a portion. Again, these embodiments entail an insert  140  that does not interfere with the faceplate  155  seating on the indentation  142 . 
     B. Inserts of the Golf Club Head 
     In contrast to traditional, single-material tour irons, the golf club head  100  comprises a low-density insert  140  that fits within the cavity  120  of the body  110 . As illustrated in  FIG.  1   , the insert  140  is shaped to fit within the cavity  120 . The insert  140  completely fills or partially fills the cavity  120 , as described above. In some embodiments, the insert  140  shares wall geometry with the cavity  120 . The shape of the insert  140  can be identical or almost identical to the shape of the cavity  120 . In embodiments where the insert substantially fills the cavity  140 , the volume and other dimensions of the insert  120  approximately correspond to the respective volume and other dimensions of the cavity  140 . As described below, manufacturing tolerances and the insertion of tape and/or adhesive into the cavity  120  can necessitate a slightly smaller volume for the insert  140  compared to the cavity  120 . 
     1) Multi-Material (Multi-Density) Inserts 
     In some embodiments, a multi-material insert  440  is employed in place of the insert  140 . The multi-material insert  440  can comprise dimensions and a volume similar to the dimensions and volume of insert  140 . The multi-material insert  440  can comprise a first portion  150  and a second portion  160  of different materials having different densities. In some embodiments, the first portion  450  is a low-density portion and the second portion  460  is a weight. Adding weight to a lower portion of the insert  440  lowers the CG  60  of the golf club head  100 , which improves launch characteristics and increases ball speed. Adding weight to lower the CG  60  can also increase ball speed and improve the feel of the golf club head  100 . In other embodiments, the first portion  450  is a vibration damping material, and the second portion  460  is a low-density material. Forming the first portion  450  from a vibration damping material can affect the feel and sound of the golf club head  100 . The feel, sound, and perimeter weighting of the golf club head  100  can be altered by forming the insert  440  from multiple materials. 
     The insert  440  can be formed with the first portion  450  and the second portion  460  in any orientation or combination with respect to each other, so long as the first and second portions  450 ,  460  form an insert  440  configured to fit within the cavity  120  of the body  110  as described above. The first portion  450  can be separate from the second portion  460  or integrally formed into a single multi-material insert  440 . Various embodiments of a multi-material insert  440 ,  440 B,  440 C, and  440 D are depicted in  FIGS.  6 - 9    and described below. 
     Referring to  FIG.  6   , the insert  440  comprises a first portion  450  and a second portion  460 . Insert  440  can be designed to fit within the cavity  120  of golf club head  100 . The cross-sectional cutaway of  FIG.  6    is taken along the centerplane  45  of the golf club head  100 . The first portion  450  of the insert  440  is adjacent the strikeplate  155  and comprises a first material. The second portion  460  of the insert  440  is adjacent the rear  103  of the body  110  and comprises a second material. The first portion  450  overlaps the second portion  460 . The first portion  450  of the insert  440  comprises a front surface that abuts a rear surface  128  of the faceplate  155 . The second portion  460  does not engage the faceplate  155 . The second portion  460  comprises a front surface that engages a rear surface of the first portion  450 . The second portion  460  is confined within a section of the cavity  120  within the lower portion  109  of the golf club head  100 . 
     In some embodiments, the engaging surfaces of one or both of the first and second portions  450 ,  460  comprise small features (not shown) that extend out from the generally planar surfaces to increase the engagement surface area. These small features can comprise protrusions, lips, ribs, hooks, or any other suitable feature. These features allow the first portion  450  to be secured onto the second portion  460  through a molding process or co-molding process. 
     Turning now to  FIGS.  7 - 9   , three more example embodiments of multi-material inserts are depicted within a cross-sectional view of the club head  100 , taken along the centerplane  45 . The second embodiment of a multi-material insert  440 B comprises a first portion  450 B and a second portion  460 B, arranged as illustrated in  FIG.  7   . In this embodiment, the first portion  450 B forms an upper section of the insert  440 B and the second portion  460 B forms a lower section of the insert  440 B. Both the first portion  450 B and the second portion  460 B are flush against the faceplate  155 . The first portion  450 B fills the section of the cavity  120  within the upper portion  108  of the body  110 . The second portion  460 B fills the section of the cavity  120  within the lower portion  109  of the body  110 . The second portion  460 B is flush against the entire interior sole wall of the cavity  120 . 
     The third embodiment of a multi-material insert  440 C comprises a first portion  450 C and a second portion  460 C, arranged as illustrated in  FIG.  8   . In this embodiment, the first portion  450 C comprises a majority of the volume of the insert  440 C. The first portion  450 C extends partially into a rear end of the insert  440 C. The entire second portion  460 C is located rearward of the first portion  450 C. The first portion  450 C is flush against the faceplate  155  from the top rail  106  to the sole  107  in the cavity of the golf club head  100 . The second portion  460 C does not engage the faceplate  155 . The second portion  460 C partially fills and is completely located in the section of the cavity  120  within the lower portion  109  of the body  110 . The second portion  460 C engages a section of an interior sole wall and rear backwall of the cavity  120 . In some embodiments, the second portion  460 C is formed from a high density material. 
     The fourth embodiment of a multi-material insert  440 D comprises a first portion  450 D and a second portion  460 D, arranged as illustrated in  FIG.  9   . In this embodiment, the first portion  450 D extends partially into a rear end of the insert  440 D. The first portion  450 D engages the second portion  460 D along a plane that is angled with respect to the loft plane  20 . Furthermore, the first portion  450 D is wider adjacent a bottom of the insert  440 D than adjacent a top of the insert  440 D. With respect to the golf club head  100 , the first portion  450 D is wider adjacent the sole  107  than adjacent the top rail  106 . The first portion  450 D is flush against the faceplate  155  from the top rail  106  to the sole  107  in the cavity  120  of the golf club head  100 . The second portion  460 D does not engage the faceplate  155 . The second portion  460 D partially fills and is completely located in the section of the cavity  120  within the lower portion  109  of the body  110 . The second portion  460 C engages a rear backwall of the cavity  120 . In some embodiments, the second portion  460 D is formed from a high density material. The golf club head  100  having the multi-material insert  440  offers feel and sound improvements over a tour iron lacking an insert. 
     In yet another embodiment of the golf club head  100  having a multi-material insert, not shown, the second portion, similar to second portions  460 ,  460 B,  460 C,  460 D, can be located primarily in the toe  101  of the golf club head  110 . This provides a toe weighting effect, acting similar to the toe weight  161 , described below. Embodiments with the second portion of the insert acting as a toe weight have no need for an external toe weight. This can improve the aesthetics and simplify manufacturing by eliminating the need for welding in a toe weight. 
     2) Volume of the Cavity Filled by Insert of the Golf Club Head 
     As mentioned above, the insert  140  can fully or partially fill the cavity  120  of the golf club head  100 . The insert  140  can fill a volume of the cavity  120  between 80% and 100%. In some embodiments, the insert  140  can fill a volume of the cavity  120  between 80% and 85%, 85% and 90%, 90% and 95%, 95% and 100%, 80% and 90%, or 90% and 100%. In embodiments having a multi-material insert, such as insert  440 , the first portion  450  can fill a majority of the cavity  120 . The second portion  460  can fill the remainder of the cavity  120 . In some embodiments, not depicted, the first and second portions together only partially fill the cavity  120 . In embodiments having a multi-material insert  440 , the first portion  450  can fill between 20% to 90% of the volume of the cavity  120 . In some embodiments, the first portion  450  can fill between 20% and 30%, 30% and 40%, 40% and 50%, 50% and 60%, 60% and 70%, 70% and 80%, or 80% and 90%. The second portion  460  can fill between 10% to 80% of the volume of the cavity  120 . In some embodiments, the second portion  460  can fill between 10% and 20%, 20% and 30%, 30% and 40%, 40% and 50%. 
     The volumes of the first and second portions  450 ,  460  affect the overall weighting of the golf club head  100  because the first and second portions  450 ,  460  are formed with different materials having different densities, as described in detail below. In the design of a golf club head, many design parameters must be considered together. By forming the insert from multiple materials, the mass placement can be controlled to increase perimeter weighting and lower the CG, leading to improved launch characteristics and higher ball speeds. 
     3) Tape Layers Combined with Insert in the Golf Club Head 
     In some embodiments, a tape layer  150  is placed within the cavity  120  between the insert  140  and the strikeface  111 . As seen in  FIG.  12   , the tape layer  150  is sandwiched between the insert  140  and the faceplate  155 . Golf club head embodiments having a multi-material insert, such as  440 , can similarly comprise a tape layer  150  between the first portion  450  and the faceplate  155  or between the first portion  450  of the insert  440  and the body  110 . Within the golf club head  100 , the insert  140  fits within the body  110 , the tape layer  150  can optionally lay on the insert  140 , and the faceplate  155  covers the tape layer  150  and fills the indentation  142  of the body  110 . 
     In some embodiments, not shown, a second tape layer can lie flush with an interior surface of the rear  103  of the body  110  within the cavity  120 . The second tape layer can be sandwiched between the rear  103  of the body  110  and the insert  140 . In some embodiments, a third tape layer can lie flush at a bottom of the cavity  120 . The third tape layer can be sandwiched between the sole  107  of the body  110  and the insert  140 . The golf club head  100  can comprise one or more of the first tape layer  150 , the second tape layer, and the third tape layer. 
     The tape layer  150 , second tape layer, or third tape layer can comprise a material such as a very high bond (hereafter “VHB”) tape. The VHB tape is compressible, such that an original thickness of the tape layer  150  (measured orthogonal to the strikeface  111 ) when initially provided is greater than a thickness of the compressed tape layer within the assembled golf club head  100 . The second and third tape layers can be similarly compressible. The compressible nature of the one or more tape layers reduces the likelihood of rattling caused by manufacturing tolerances between the body  110  and the insert  140 . Furthermore, the one or more tape layers can provide vibration damping as well as positively affect the feel and sound of the golf club head  100 . 
     C. Faceplate of the Golf Club Head 
     The full golf club head  100  is formed by the combination of the body  110 , the insert  120 , and the faceplate  155 . The body  110  comprises an opening of the cavity  120  at the front  104  of the golf club head  100 . The opening is covered by the faceplate  155 , to entirely enclose the cavity  120  and the insert  140 . As shown in  FIGS.  2  and  3   , the cavity  120  and the insert  140  are not visible from the outside of the golf club head  100  when the insert  140  is positioned within the cavity  120 . By concealing the insert  140  within the golf club head  100 , the look of the golf club head  100  can resemble the look of traditional tour irons. 
     Consequently, a portion of the front  104  of the body  110  and the faceplate  155  form the strikeface  111 . The strikeface  111  can cover between 70% and 95% of the surface area of the front  104  of the golf club head  100 . In some embodiments, the strikeface  111  can cover between 70% and 80%, 75% and 85%, 80% and 90%, or 85% and 95% of the surface area of the front of the golf club head  100 . Furthermore, a front surface of the strikeface  111  may comprise one or more grooves. In some embodiments, the grooves extend beyond the edge of the faceplate  155  and onto a portion of the body  110 . 
     The faceplate  155  can comprise a different material than the body  110 , as described below. In some embodiments, the material of the faceplate  155  is stronger than the material of the body  110 . To exploit the benefits of the faceplate  155  material, the majority of the strikeface  111  is formed by the faceplate  155 . The faceplate  155  can form between 50% and 95% of the surface area of the front  104  of the golf club head  100 . In some embodiments, the faceplate  155  can form between 50% and 60%, 60% and 70%, 70% and 80%, 80% and 90%, or 85% and 95% of the surface area of the strikeface  111 . Despite having different materials, the faceplate  155  and the body  110  portion of the strikeface  111  both give a solid feel because the insert  140  solidly supports the faceplate  155 . The body  110 , the insert  140 , and the faceplate  155  can all contribute to a consistent feel and sound for the golf club head  100  when the golf club head  100  impacts a golf ball on various regions of the faceplate  155 . 
     1) Other Faceplate Characteristics 
     The support provided to the faceplate  155  by the insert  140  enables a thin faceplate  155  to be used in the golf club head  100 . As illustrated in  FIG.  5   , the faceplate  155  of the golf club head  100  has a thickness  112 . The thickness  112  can range between 0.030 inch and 0.100 inch. In some embodiments, the faceplate thickness  112  can be 0.030 inch, 0.040 inch, 0.050 inch, 0.060 inch, 0.070 inch, 0.080 inch, 0.090 inch, or 0.100 inch. The faceplate thickness  112  can be constant across the faceplate  155 . In some embodiments, the faceplate thickness  112  can vary in a heel-to-toe direction or in a top rail-to-sole direction. In some embodiments, the faceplate thickness  112  can vary in a radial direction from a center of the faceplate  155 . 
     In other embodiments, the faceplate  155  can further comprise variable thickness regions. In some embodiments, a central region of the faceplate  155  can be thicker than a peripheral region of the faceplate  155 . In some embodiments, the thickened central region can comprise an elliptical shape. The thickness of the faceplate  155  can taper from the central towards a periphery of the faceplate  155 . 
     D. Other Peripheral Weights (Tip Weights, Toe Weights) in the Golf Club Head 
     In addition to the perimeter weighting and swing characteristics provided by the insert  140  and the body  110 , the golf club head  100  can further comprise other perimeter types of weights. In some embodiments, the golf club head  100  can further comprise a tip weight  160 . The tip weight  160  is a weight that fits at the juncture between the hosel  105  and the golf club shaft. The tip weight  160  provides additional perimeter weighting to the club head  100 . As illustrated in  FIG.  13   , the tip weight  160  fits within the hosel  105  of the body  110 . The tip weight  160  can by cylindrical, spherical, cube-shaped, or any other suitable shape. The tip weight  160  may be located higher or lower in the hosel  105  than is pictured in  FIG.  13   . 
     As illustrated in  FIGS.  1  and  13   , the body  110  of the golf club head  100  can further comprise a toe cavity  114 . The toe cavity  114  is designed to house a toe weight  161 , which improves the perimeter weighting and swing characteristics of the golf club head  100 .  FIG.  3    illustrates the toe cavity  114  with the toe weight  161  installed.  FIG.  13    illustrates the toe weight  161  removed from the toe cavity  114 . In some embodiments, the toe cavity  114  is located partially in the sole  107  and partially in the toe  101 . In some embodiments, the toe cavity  114  is located fully in the toe  101  of the golf club head  100 , adjacent the sole  107 . In some embodiments, the toe cavity  114  is located completely in the sole  107 , adjacent the toe  101 . In some embodiments, the toe cavity  114  is located completely in the toe  101 . In some embodiments, the toe cavity  114  is located in the center of the toe  101 , approximately half way between the top rail  106  and the sole  107 . 
     In some embodiments, the toe cavity  114  is visible from the rear view of the body  110  of the club head  100 . In other embodiments, the toe cavity  114  is not visible from the rear view of the body  110 . In some embodiments, the toe cavity  114  is visible from the toe-side view of the body  110 . In other embodiments, the toe cavity  114  is not visible from the toe-side view of the body  110 . In some embodiments, the toe cavity  114  is visible from the sole view of the body  110 . In other embodiments, the toe cavity  114  is not visible from the sole view of the body  110 . In the embodiment of  FIGS.  1 - 13   , the toe cavity  114  is visible from the rear view, the sole view, and the toe-side view. 
     The toe weight  161  is shaped to match the contours of the toe cavity  114  of the body  110 . An external wall of the toe weight  161  is designed follow the curve of the golf club head body  110 . In some embodiments, the mass of the toe weight  161  can be between 5% and 45% of the mass of the body  110 . In some embodiments, the mass of the toe weight  161  can be between 5% and 20%, 5% and 15%, 10% and 20%, 15% and 25%, 20% and 40%, 20% and 30%, 30% and 40%, or 35% and 45% of the mass of the body  110 . 
     In some embodiments, the body  110  of the golf club head  100  can further comprise a toe screw weight port, not depicted, in the toe  101 . The golf club head  100  can further comprise a toe screw weight that fits within the screw weight port. In some embodiments, the toe screw weight can comprise a weight between 2 grams and 15 grams, as described below. A screw weight having one weight value can be exchanged for a different screw weight having a different weight value in order to customize the golf club head  100  to a golfer&#39;s swing. 
     In some embodiments, there is a combination of weights as described above including the insert, toe weight, tip weight, and the toe screw weight. Other embodiments can comprise a multi-material insert combined with one or more of a toe weight, a tip weight, and a toe screw weight. 
     E. Materials 
     The materials that form the body  110 , the insert  140 , and the faceplate  155  affect the mass distribution of the golf club head  100 . Consequently, the MOI and CG of the golf club head  100  are also affected by the densities of the materials. Furthermore, the materials provide the strength and flexibility necessary for the golf club head  100 . The golf club head  100  comprises one or more, two or more, three or more, or four or more materials. In some embodiments, the materials may be a first density, second density, third density, fourth density, fifth density or sixth density. 
     In some embodiments, the faceplate  155  can comprise a first material of a first density. The body  110  can comprise a second material of a second density. The insert  140  can comprise a third material of a third density. The third density can be less than the first density and/or the second density. In some embodiments, the faceplate  155  can be the same material as the body  110  (and thereby the same densities). As discussed above and in some embodiments, the insert  440  can comprise two or more materials wherein the materials are a different density over each other, and can be different or the same over the materials of the faceplate  155  and/or the body  110 . 
     1) Body Materials 
     The body  110  may comprise a material, such as steel, a steel alloy, or any other suitable material. In some embodiments, the body  110  can comprise a material of a density that is different over the faceplate  155  and the insert  140 . The material can comprise a material selected from the group consisting of a steel-based material or a steel alloy. In some embodiments, the body material can be 8620 carbon steel, which comprises iron and approximately 0.17-0.23% wt. carbon, 0.15-0.35% wt. silicon, 0.60-0.90% wt. manganese, 0.15-0.30% wt. molybdenum, 0.40-0.70% wt. nickel, 0.40-0.65% wt. chromium, 0.040% wt. phosphorus, and trace amounts of other elements. In some embodiments, the body material can be 300 grade steel, which comprises iron and approximately 18-19% wt. nickel, 8.5-9.5% wt. cobalt, 4.6-5.2% wt. molybdenum, 0.5-0.8% wt. titanium, 0.05-0.15% wt. aluminum, and trace amounts of other elements. In some embodiments, the body material can be maraging steel, which comprises iron and approximately 17-19% wt. nickel, 8-12.5% wt. cobalt, 3.0-5.2% wt. molybdenum, 0.15-1.6% wt. titanium, 0.05-0.15% wt. aluminum, and trace amounts of other elements. The density of the body  110  material can range between 7.70 and 8.10 grams per cubic centimeter (hereafter “g/cc”). In some embodiments, the density of the body material can be 7.70 g/cc, 7.75 g/cc, 7.80 g/cc, 7.85 g/cc, 7.90 g/cc, 7.95 g/cc, 8.05 g/cc, or 8.10 g/cc. In one embodiment, the density of the body material is 7.85 g/cc. 
     2) Insert Materials 
     The insert  140  comprises a material, such as titanium, a titanium alloy, aluminum, an aluminum alloy, an elastomer, a polymer matrix composite, any other suitable low density material, or any other suitable density material that is lower than the body  110  material. The aluminum alloy can be high strength aluminum alloy, or a composite aluminum alloy coated with a high-strength alloy. The polymer matrix composite can be a glass-filled elastomer, a stainless steel-filled elastomer, a tungsten-filled elastomer, a thermoplastic polyurethane (TPU), a thermoplastic elastomer (TPE), or any other elastomer matrix composite, a Kevlar® (aramid) fiber-reinforced polymer, a carbon-fiber reinforced polymer, or any combination of a suitable resin and a suitable reinforcing fiber. The polymer matrix composite material can be an elastomer matrix composite. In some embodiments the metal material can be a steel-based material, a titanium-based material, an aluminum alloy, a titanium alloy, or any combination thereof. The steel-based material can be a 17-4 PH stainless steel, 431, 455, 475, C300, a maraging steel, or other types of stainless steel. The aluminum alloy can be high strength aluminum alloy, or a composite aluminum alloy coated with a high-strength alloy. The titanium alloy can be Ti-9S, Ti-6-4, and Ti-15-3-3-3. The titanium alloy can be an α-β titanium alloy. 
     The insert  140  may comprise a material of a density that is different over the body  110  and the faceplate  155 . Suitable materials for the insert  140  can include any materials that have a density lower than the density of the body material. In some embodiments, particularly ones with a metal insert material, the density of the insert  140  material can range between 2.4 to 5.0 g/cc. In some embodiments, the density of the insert  140  material can be 2.4 g/cc, 2.5 g/cc, 2.6 g/cc, 2.7 g/cc, 2.8 g/cc, 2.9 g/cc, 3.0 g/cc, 3.1 g/cc, 3.2 g/cc, 3.3 g/cc, 3.4 g/cc, 3.5 g/cc, 3.6 g/cc, 3.7 g/cc, 3.8 g/cc, 3.9 g/cc, 4.0 g/cc, 4.1 g/cc, 4.2 g/cc, 4.3 g/cc, 4.4 g/cc, 4.5 g/cc, 4.6 g/cc, 4.7 g/cc, 4.8 g/cc, 4.9 g/cc, or 5.0 g/cc. In one embodiment, the insert  140  material is aluminum and the density of the insert  130  material is approximately 2.7 g/cc. In another embodiment, the insert  140  material is titanium and the density of the insert  140  material is approximately 4.5 g/cc. 
     In some embodiments, particularly ones with a polymer matrix composite material, the density of the insert  140  can range between 1.0 and 12.0 g/cc. In polymer matrix composite material preferred embodiments, the density of the insert  140  can range between 1.0 g/cc and 5.0 g/cc. In some embodiments, the density of the insert  140  can be 1.0 g/cc, 1.5 g/cc, 2.0 g/cc, 2.5 g/cc, 3.0 g/cc, 3.5 g/cc, 4.0 g/cc, 4.5 g/cc, or 5.0 g/cc. When the density of the insert  140  is low, a central portion of the club head that houses the insert  140  is lighter, allowing weight to be redistributed to the periphery of the club head. The redistributed weight increases the MOI. 
     In some embodiments of the golf club head  100 , the insert  440  comprises distinct portions formed from different materials and different densities. In some embodiments, the first and second portions  450 ,  460  of the insert  440  can each be formed from any of the materials mentioned above for the single-material insert. In some embodiments, the first portion  450  of the insert  140  is formed from an elastomer or polymer matrix composite material, comprising a density between 0.8 g/cc and 1.4 g/cc, and the second portion  460  of the insert  440  is formed from aluminum or an aluminum alloy, comprising a density between 1.5 g/cc and 3.0 g/cc. 
     In some embodiments of the golf club head  100 , the first portion  450  of the insert  440  can comprise any of the material mentioned above having a density between 1.0 g/cc and 12.0 g/cc. In some embodiments, the second portion  460  of the insert  440  can comprise a material that has a density higher than the density of the body material. In some embodiments, the second portion  460  of the insert  440  can be a weight portion comprising any of the materials described below for the toe weight  161  and having a density between 14.0 and 19.6 g/cc. In some of these embodiments, the toe weight  161  is not necessary, because the second portion  460  of the insert  140  serves a similar purpose. 
     The weight of the insert  140  or  440  can range between 10 grams and 50 grams. In some embodiments, the weight of the insert  140  can be 10 grams, 11 grams, 12 grams, 13 grams, 14 grams, 15 grams, 16 grams, 17 grams, 18 grams, 19 grams, 20 grams, 21 grams, 22 grams, 23 grams, 24 grams, 25 grams, 26 grams, 27 grams, 28 grams, 29 grams, 30 grams, 31 grams, 32 grams, 33 grams, 34 grams, 35 grams, 36 grams, 37 grams, 38 grams, 39 grams, 40 grams, 41 grams, 42 grams, 43 grams, 44 grams, 45 grams, 46 grams, 47 grams, 48 grams, 49 grams, or 50 grams. In multi-material insert embodiments where the second portion  460  of the insert comprises a material similar to the material of the toe weight  161  described below, the insert  140  or  440 , and the weight of the insert  140  or  440  can range between 10 grams and 70 grams. In some embodiments, the weight of the multi-material insert  140  or  440  can be between 10 grams and 20 grams, 20 grams and 30 grams, 30 grams and 40 grams, 40 grams and 50 grams, 50 grams and 60 grams, or 60 grams and 70 grams. 
     Furthermore, the insert  140  and  440  provides structural support to the strikeface  111 . For embodiments having a metal insert material, the insert  140  or  440  or a portion of the insert  140  or  440  can comprise a Rockwell B hardness between 30 HRB and 100 HRB. In some embodiments, the insert  140  or  440  or a portion of the insert  140  or  440 , can have Rockwell B hardness between 30 HRB and 40 HRB, 40 HRB and 50 HRB, 50 HRB and 60 HRB, 60 HRB and 70 HRB, 70 HRB and 80 HRB, 80 HRB and 90 HRB, 90 HRB and 100 HRB. In other embodiments the insert  140  or a portion of the insert  140  can have a Rockwell B hardness of 30 HRB, 31 HRB, 32 HRB, 33 HRB, 34 HRB, 35 HRB, 36 HRB, 37 HRB, 38 HRB, 39 HRB, 40 HRB, 41 HRB, 42 HRB, 43 HRB, 44 HRB, 45 HRB, 46 HRB, 47 HRB, 48 HRB, 49 HRB, 50 HRB, 51 HRB, 52 HRB, 53 HRB, 54 HRB, 55 HRB, 56 HRB, 57 HRB, 58 HRB, 59 HRB, 60 HRB, 61 HRB, 62 HRB, 63 HRB, 64 HRB, 65 HRB, 66 HRB, 67 HRB, 68 HRB, 69 HRB, 70 HRB, 71 HRB, 72 HRB, 73 HRB, 74 HRB, 75 HRB, 76 HRB, 77 HRB, 78 HRB, 79 HRB, 80 HRB, 81 HRB, 82 HRB, 83 HRB, 84 HRB, 85 HRB, 86 HRB, 87 HRB, 88 HRB, 89 HRB, 90 HRB, 91 HRB, 92 HRB, 93 HRB, 94 HRB, 95 HRB, 96 HRB, 97 HRB, 98 HRB, 99 HRB, or 100 HRB. For other embodiments having a metal insert the insert  140  or  440  or a portion of the insert  140  or  440  can comprise a Rockwell C hardness between 30 HRC and 60 HRC. In some embodiments, the insert  140  or  440  can have a hardness between 30 HRC and 40 HRC, 35 HRC and 45 HRC, 40 HRC and 50 HRC, 45 HRC and 50 HRC, or 50 HRC and 60 HRC. In other embodiments, the insert can have a Rockwell C hardness of 30 HRC, 31 HRC, 32 HRC, 33 HRC, 34 HRC, 35 HRC, 36 HRC, 37 HRC, 38 HRC, 39 HRC, 40 HRC, 41 HRC, 42 HRC, 43 HRC, 44 HRC, 45 HRC, 46 HRC, 47 HRC, 48 HRC, 49 HRC, 50 HRC, 51 HRC, 52 HRC, 53 HRC, 54 HRC, 55 HRC, 56 HRC, 57 HRC, 58 HRC, 59 HRC, or 60 HRC. For some embodiments comprising a titanium or titanium alloy insert  140  or  440 , the insert hardness is 44 HRC. 
     3) Faceplate Materials 
     The faceplate  155  can be formed from a faceplate material. In some embodiments, the faceplate material is the same material as the body  110  material. In other embodiments, the faceplate material is a different material than the body material. In some embodiments, the faceplate  155  can comprise a material of a density that is different over the body  110  and the insert  140 . 
     The faceplate material can be a steel-based material, a titanium-based material, a titanium alloy, or any combination thereof. The steel-based material can be a carbon steel, a 17-4 PH stainless steel, 431, 455, 475, C300, a maraging steel, or other types of stainless steel. The titanium alloy can be Ti-7S+(ST721), Ti-9S, Ti-6-4, Ti-15-3-3-3, or any other suitable titanium alloy. The titanium alloy may be an α-β titanium alloy. In embodiments where the faceplate  155  is a titanium-based material, an aluminum alloy, a titanium alloy, or any combination thereof, the density of the faceplate  155  material can range between 2.6 and 8.7 g/cc. In some embodiments, the density of the faceplate material can be 2.6 g/cc, 2.8 g/cc, 3.0 g/cc, 3.2 g/cc, 3.4 g/cc, 3.6 g/cc, 3.8 g/cc, 4.0 g/cc, 4.2 g/cc, 4.4 g/cc, 4.6 g/cc, 4.8 g/cc, 5.0 g/cc, 5.2 g/cc, 5.4 g/cc, 5.6 g/cc, 5.8 g/cc, 6.0 g/cc, 6.2 g/cc, 6.4 g/cc, 6.6 g/cc, 6.8 g/cc, 7.0 g/cc, 7.2 g/cc, 7.4 g/cc, 7.6 g/cc, 7.8 g/cc, 8.0 g/cc, 8.2 g/cc, 8.4 g/cc, 8.6 g/cc, or 8.7 g/cc. In embodiments where the faceplate  155  is a steel-based material, the density of the faceplate material can range between 7.7 g/cc and 8.1 g/cc. 
     4) Tip Weight Material 
     The tip weight  160  can comprise a material that is different over the material of the body  110 , faceplate  155 , and the insert  140  or  440 . The tip weight  160  comprises a high-density material, such as tungsten or any other suitable metal or metal alloy material. The density of the tip material  160  can range between 1.1 g/cc and 19.6 g/cc. In some embodiments, the density of the tip weight  160  material can be 1.1 g/cc, 1.5 g/cc, 2.0 g/cc, 2.5 g/cc, 3.0 g/cc, 3.5 g/cc, 4.0 g/cc, 4.5 g/cc, 5.0 g/cc, 5.5 g/cc, 6.0 g/cc, 6.5 g/cc, 7.0 g/cc, 7.5 g/cc, 8.0 g/cc, 8.5 g/cc, 9.0 g/cc, 9.5 g/cc, 10.0 g/cc, 10.5 g/cc, 11.0 g/cc, 11.5 g/cc, 12.0 g/cc, 12.5 g/cc, 13.0 g/cc, 13.5 g/cc, 14.0 g/cc, 14.5 g/cc, 15.0 g/cc, 15.5 g/cc, 15.8 g/cc, 16.0 g/cc, 16.2 g/cc, 16.4 g/cc, 16.6 g/cc, 16.8 g/cc, 17.0 g/cc, 17.2 g/cc, 17.4 g/cc, 17.6 g/cc, 17.8 g/cc, 18.0 g/cc, 18.2 g/cc, 18.4 g/cc, 18.6 g/cc, 18.8 g/cc, 19.0 g/cc, 19.2 g/cc, 19.4 g/cc, or 19.6 g/cc. The weight of the tip weight  160  can range between 0 grams and 18 grams. In some embodiments, the weight of the tip weight  160  can be 0 grams (in the embodiment where there is no tip weight), 1 grams, 2 grams, 3 grams, 4 grams, 5 grams, 6 grams, 7 grams, 8 grams, 9 grams, 10 grams, 11 grams, 12 grams, 13 grams, 14 grams, 15 grams, 16 grams, 17 grams, or 18 grams. In most embodiments, the tip weight  160  ranges between 0 grams and 9 grams. 
     5) Toe Weight Material 
     The toe weight  161  can comprise a material that is different over the material of the body  110 , faceplate  155 , the tip weight  160 , and the insert  140  or  440 . The toe weight  161  comprises a high-density material, such as tungsten or any other suitable metal or metal alloy material. The density of the toe weight  161  material can range between 14.0 and 19.6 g/cc. In some embodiments, the density of the toe weight  161  material can be 14.0 g/cc, 14.2 g/cc, 14.4 g/cc, 14.6 g/cc, 14.8 g/cc, 15.0 g/cc, 15.2 g/cc, 15.4 g/cc, 15.6 g/cc, 15.8 g/cc, 16.0 g/cc, 16.2 g/cc, 16.4 g/cc, 16.6 g/cc, 16.8 g/cc, 17.0 g/cc, 17.2 g/cc, 17.4 g/cc, 17.6 g/cc, 17.8 g/cc, 18.0 g/cc, 18.2 g/cc, 18.4 g/cc, 18.6 g/cc, 18.8 g/cc, 19.0 g/cc, 19.2 g/cc, 19.4 g/cc, or 19.6 g/cc. The weight of the toe weight  161  can range between 10 grams and 40 grams. In some embodiments, the weight of the toe weight  161  can be 10 grams, 11 grams, 12 grams, 13 grams, 14 grams, 15 grams, 16 grams, 17 grams, 18 grams, 19 grams, 20 grams, 21 grams, 22 grams, 23 grams, 24 grams, 25 grams, 26 grams, 27 grams, 28 grams, 29 grams, 30 grams, 31 grams, 32 grams, 33 grams, 34 grams, 35 grams, 36 grams, 37 grams, 38 grams, 39 grams, and 40 grams. In some embodiments, the weight of the toe weight  161  can range between 12 grams and 26.5 grams. 
     6) Toe Screw Weight Material 
     The toe screw weight (swing weight) can comprise any high-density material similar to the high-density materials of the tip weight or the toe weight. The density of the toe screw material can be similar to the density of the tip weight materials. The weight of the toe screw weight can be similar to the weight of the tip weight, described above. 
     II. Golf Club Head with Rear Opening 
     Described herein is a golf club head  600 . Like golf club head  100 , golf club head  600  can be a tour style golf club head with forgiveness as discussed above. The golf club head  100  can comprises a body  610  having a cavity  620  that houses an insert  640 . The golf club head  600  comprises a faceplate  655 , a body  610 , and an insert  640 . The body  610  comprises an upper portion  608 , a lower portion  609 , a sole  607 , a rear  603 , and a top rail  606 . The rear  603  can further comprise an inflection seam  630 . The inflection seam  630  is the boundary between the upper portion  608  and lower portion  609  of the golf club head  600 . The faceplate  655  and a portion of the body define a strikeface  611  (striking surface) of the golf club head. The faceplate  655 , the sole  607 , the rear  603 , and the top rail  606  enclose a cavity  620 . 
       FIGS.  14 - 23    depict a golf club head  600  similar to golf club head  100 . The golf club head  600  comprises a body  610  forming a cavity  620 , a faceplate  655 , a rear opening  680  and a low-density insert  640  in the cavity. The body  610  comprises an upper portion  608 , a lower portion  609 , a sole  607 , a rear  603 , and a top rail  606 . The rear  603  can further comprise an inflection seam  630 . The inflection seam  630  is the boundary between the upper portion  608  and lower portion  609  of the golf club head  600 . The faceplate  655  and a portion of the body  610  define a strikeface  611  (striking surface) of the golf club head  600 . 
     The body  610  is similar to body  110 . The faceplate  655 , the sole  607 , and the rear  603  form a cavity  620  with a rear opening  680  in the upper portion  608  of the golf club head  600 . The rear opening  680  of the body  610  partially exposes the cavity  620 . After assembly, the insert  640  is visible through the opening  680  in the rear  603 . The body  610  further comprises an indentation  642  in the front  604  of the body  610  for receiving the faceplate  655  similar to the indentation  142  described above for club head  100 . 
     The insert  640  harbors within the cavity  620 . The insert  640  can comprise a non-metal or polymer based material. The insert material can be injected into the cavity  620  of the golf club head  600  through the rear opening  680  to form the insert  640  within the cavity  620 . In other embodiments, the insert  640  can comprise a metal material, similar to the insert  140  described above. The faceplate  655  encloses the cavity  620  at a front  604  of the golf club head  600 . The faceplate  655  and a front  604  of the body  610  together define a strikeface  611 . 
     The golf club head  600  is a tour iron club head, and has a volume between 1.8 cubic inches and 2.7 cubic inches (30 cubic centimeters (cc) and 45 cc). The body  610  of the golf club head  600  can be cast or forged from a metal material. 
     The insert  640  comprises a low-density material and fills the cavity  620  formed by the body  610  of the golf club head  600 . Reducing mass in the center of the golf club head  600  allows extra mass to be concentrated at its perimeter to increase moment of inertia values of the golf club head  600 . As discussed above, the golf club head  600  comprises a lower portion  609  and an upper portion  608 . The lower portion  609  comprises a depth greater than the upper portion  608 . The lower portion  609  thereby has more mass concentrated on the peripheral heel  602 , toe  601 , and the sole  607 . Lowering the mass of the body  610  results in a low CG  60 , which increases launch angle, reduces spin, and increases ball speed. As introduced above, there is a need in the art for an iron that couples tour iron sizing with a comparatively high moment of inertia from perimeter weighting and a low CG from low positioning of mass. In some embodiments, a tip weight  660  positioned in the hosel and/or a toe weight  661  positioned in a toe cavity  614  of the body  610  provide additional perimeter weighting. In some embodiments, a toe screw weight  662  (swing weight) positioned in a toe screw weight cavity  663  (swing weight cavity) of the body  610  provides additional perimeter weighting. 
     The golf club head  600  can be described with the same reference planes and axes as golf club head  100 . The definitions of the ground plane  10 , loft plane  20 , centerplane  45 , centerpoint  80 , lead edge axis  35 , lead edge plane, x-axis  30 , y-axis  40 , z-axis  50 , and hosel axis  70  remain the same for golf club head  600  as for golf club head  100 . 
     A. Parts of the Golf Club Head 
     As discussed above and illustrated in  FIGS.  15  and  16   , the body  610  comprises at least an upper portion  608 , a lower portion  609 , a sole  607 , a top rail  606 , a rear  603 , a front  604 , a toe  601 , a heel  602 , and a hosel  605  respectively similar to the upper portion  108 , the lower portion  109 , sole  107 , top rail  106 , rear  103 , front  104 , toe  101 , heel  102 , and hosel  605  of golf club head  100 . In some embodiments, the faceplate  655  that is welded or swedged (swagged) over the front opening of the body  610 . 
     The body  610  comprises an inflection seam  630  and rear contours similar to the inflection seam  130  and rear contours of golf club head  100 . The heights of the upper and lower portions  608 ,  609 , the depths of the upper and lower portions  608 ,  609 , and the thickness of the rear  603  are similar to the heights of the upper and lower portions  108 ,  109 , the depths of the upper and lower portions  108 ,  109 , and the thickness of the rear  103  of golf club head  100 . 
     The body  610  further comprises an opening wall  682  in the rear of the body  610 . The opening wall  682  defines the rear opening  680 . The rear opening  680  of the body  610  is located in upper portion  608  of the club head  600 , which is above the inflection seam  630 . The uniform depth of the upper portion  608  in conjunction with the location of the rear opening  680  fully in the upper portion  608  allows for a flat surface surrounding the opening  680 . On all sides of the opening wall  682  of the body  610  (the rear opening  680 ), an exterior surface of the golf club head  600  is planar. This planar surface is necessary to provide a seal around the rear opening  680  during injection of the insert material into the cavity  620  during manufacturing, as described further below. 
     To identify the size of the rear opening  680 , a projected area can be taken of the rear  603  (not including the hosel  605  or the sole  607 ), parallel to the loft plane  20 . The projected area of the rear  603  can be compared to the projected area circumscribed by the opening wall  682 . The opening wall  682  circumscribes (the rear opening covers) an area between 25% and 50% of a projected area of a rear  603  of the club head  600 . In some embodiments, the opening wall  682  can circumscribe a percent of the rear area between 25% and 30%, 25% and 35%, 30% and 40%, 35% and 45%, 40% and 50%, or 45% and 50%. In other embodiments, the opening wall  682  can circumscribe a percent of the rear area of 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%. 
     In some embodiments, the insert  640  is visible through the rear opening  680 . In some embodiments, between 10% and 60% of the insert can be visible through the rear opening  680 . In some embodiments, between 10% and 20%, 15% and 25%, 20% and 30%, 25% and 35%, 30% and 40%, 35% and 45%, 40% and 50%, 45% and 55%, or 50% and 60% of the insert  640  can be visible through the rear opening  680 . In some embodiments, a badge, not shown, is placed over the rear opening  680 . In these embodiments, the badge can cover between 10% and 60% of the insert. In some embodiments, the badge can cover between 10% and 20%, 15% and 25%, 20% and 30%, 25% and 35%, 30% and 40%, 35% and 45%, 40% and 50%, 45% and 55%, or 50% and 60% of the insert  640 . 
     The rear  603  with an opening wall  682  defining a rear opening  680  contributes to a low mass of the upper portion  608 . Filling the rear opening  680  with a material having a density lower than the density of the body material results in a golf club head  600  having a low CG. Reducing the mass of the upper portion  608  both lowers CG and allows weight to be distributed to the perimeter to improve the golf club head&#39;s forgiveness. Various design parameters can contribute to a low mass of the upper portion. As described above for golf club head  100 , the keeping a uniform upper portion depth also contributes to a low mass of the upper portion  608 . 
     Since the material used to form the body  610  generally has a higher density than the material of the insert  640 , the mass of the upper portion  608  can be reduced by replacing the portion of the rear body  610  circumscribed by the opening wall  682  with insert material. When compared to a similar golf club head having a solid rear formed fully from a body material, the golf club head  600  comprises a lower CG because of the rear opening  680 . The percent projected area of the opening  680  and the density of the insert material can reduce the mass of the upper portion  608  by between 1 gram and 17 grams. In some embodiments, the mass of the upper portion  608  can be reduced by between 1 gram and 3 grams, 3 grams and 5 grams, 5 grams and 7 grams, 7 grams and 9 grams, 9 grams and 11 grams, 11 grams and 13 grams, 13 grams and 15 grams, or 15 grams and 17 grams. In other embodiments, the mass of the upper portion  608  can be reduced by 1 gram, 2 grams, 3 grams, 4 grams 5 grams, 6 grams, 7 grams, 8 grams, 9 grams, 10 grams, 11 grams, 12 grams, 13 grams, 14 grams, 15 grams, 16 grams, or 17 grams. This reduction in the mass of the upper portion  108  of the body  610  assists in lowering the CG, improving launch and spin characteristics and increasing ball speed. 
     The body  610  of the golf club head  600  defines the cavity  620 . The cavity  620  of the body  610  can be configured to receive a low-density insert  640  that increases the MOI of the golf club head  600  without sacrificing the desirable solid feel of a tour iron. The regions, volumes, and contours of the cavity  620  are similar to the regions, volumes, and contours of cavity  120 . Adjacent a front opening of the cavity  620 , the body  610  comprises an internal peripheral edge  627 , similar to the internal peripheral edge  127  of golf club head  100 . The sole  607 , the top rail  606 , the rear  603 , the internal peripheral edge  627 , and the faceplate  655  define the cavity  620 . The cavity  620  both connects to the rear opening  680  of the body  610  and is enclosed at the front  604  of the body  610  by the faceplate  655 . The cavity  620  is exposed through the rear opening  680  of the rear  603  of the body  610 . 
     B. Insert of the Golf Club Head 
     The insert  640  is configured to fit within the cavity  620  of the body  610  in order to increase the MOI and retain the solid feel of the golf club head  600 . The volume of the insert  640  can be similar to the volume of the insert  140  of golf club head  100 . In some embodiments, the volume of the insert  640  can be greater than the volume of the cavity  620  because the insert  640  extends beyond the cavity  620  into the rear opening  680 . 
     The insert  640  completely fills or partially fill the cavity  620 , as described above for golf club head  100 . The insert  640  can fill a percent volume of the cavity  620 , as described for golf club head  100 . In some embodiments, as illustrated in  FIG.  19   , the insert  640  can fill 100% of the cavity  620  and extend into the rear opening  680 . As illustrated in  FIG.  20   , the insert  640  can fill 60% of the cavity  620 . As illustrated in  FIG.  21   , the insert  640  can fill 70% of the cavity  620  and extend partially into the rear opening  680 . As illustrated in  FIG.  22   , the insert  640  can fill 80% of the cavity  620  and extend partially into the rear opening  680 . As illustrated in  FIG.  23   , the insert  640  can fill 90% of the cavity  620  and extend partially into the rear opening  680 . In some embodiments, not shown, the insert  640  can fill only the cavity  620  and not fill the rear opening  680 . In some embodiments, the insert  640  can comprise a metal material and fill only the cavity  620 . In this example embodiment, not shown, the opening wall  682  of the body  610  can taper to blend into the insert  640 , providing a less distinct boundary for the rear opening  680 . 
     In some embodiments, the insert  640  is formed prior to insertion into golf club head  600 , as described below. In other embodiments, the insert  640  is formed within the cavity  620  of the body  610 . In these embodiments, the opening wall  682  that forms the rear opening  680  can serve as a port for the insert  640  to be injected into the cavity  620 , as described below. 
     C. Cavity of the Body 
     A front surface of the body cavity  620  can be enclosed by the faceplate  655 . The faceplate  655  and the strikeface  611  can be similar to the faceplate  155  and strikeface  611  of golf club head  100 . However, in some embodiments, the strikeface  611  can be integrally formed with the body  610 . The strikeface  611  comprises a thickness  612  similar to the thickness  112  of strikeface  111  of golf club head  100 . 
     The body  610  is partially or fully filled by the insert  640 , which is secured within the golf club head  600  by the faceplate  655 . In some embodiments, the cavity  620  further houses a tape layer  150  and/or adhesive, similar to the tape layer  150  and/or adhesive of golf club head  100 . 
     In some embodiments, the golf club head  600  further comprises a shaft tip weight  660 , similar to the shaft tip weight  160  of golf club head  100 . In some embodiments, the body  610  further comprises a toe cavity  614  housing a toe weight  661 , similar to the toe cavity  114  and toe weight  161  of golf club head  100 . The golf club head  600  can further comprise a toe screw cavity  663  and a toe screw weight  662  for adjusting swing weighting, as depicted in  FIGS.  17  and  18   . The toe screw weight can comprise a weight between 2 grams and 15 grams, as described for the optional toe screw weight of golf club head  100 . The toe screw weight  662  can be removed and replaced with a different screw weight  662  having a different weight value to customize the golf club head  600  to a golfer&#39;s swing. 
     D. Materials of the Club Head Body with Rear Opening 
     The materials used to form the components of golf club head  600 , can be similar to the materials used to form the components of golf club head  100 , as described above. In particular, the body  610  can comprise the same body material as body  110 . The insert  640  can comprise the same insert material as insert  140 . The faceplate  655  can comprise the same faceplate material as faceplate  155 . The toe weight  661 , tip weight  660 , and toe screw weight  662  can comprise the same materials as the toe weight  161 , tip weight  160 , and toe screw weight materials as golf club head  100 . 
     III. Golf Club Head Characteristics 
     A. Golf Club Head Measurements 
     The golf club head  100 ,  600  can be a tour iron. The golf club heads  100 ,  600  described herein can be a tour iron head comprising a blade length, a hosel-x length, an offset distance, and an upper portion depth characteristic of tour iron. 
     As illustrated in  FIG.  2   , the golf club head  100  comprises a blade length  173 . The blade length  173  is measured as the maximum distance from an edge of the strikeface  111  in the heel region  102  to an edge of the club head  100  in the toe region  101 . The blade length of a generic tour iron can be less than 2.8 inches. The blade length of a game-improvement iron is generally greater than 2.8 inches. The blade length  173  of golf club head  100  is less than 2.8 inches, as is characteristic of a tour iron. In some embodiments, the blade length  173  of golf club head  100  can be between 2.2 inch and 2.8 inch, 2.2 inch and 2.4 inch, 2.4 inch and 2.6 inch, or 2.6 inch and 2.8 inch. 
     As illustrated in  FIG.  2   , a hosel-X length  174  is measured from the centerplane  45  to an intersection of the hosel axis  70  with the lead edge axis  35 . The hosel-X length of a tour iron is generally less than 1.5 inches, and the hosel-X length of a game improvement iron is generally greater than 1.5 inches. The hosel-X length of the golf club head  100  is less than 1.5 inches, as is characteristic of a tour iron. In some embodiments, the hosel-X length  174  can be between 1.30 inches and 1.50 inches, 1.30 inches and 1.40 inches, or 1.40 inches and 1.50 inches. 
     As illustrated in  FIG.  4   , an offset distance  173  is measured between a forward edge of the hosel  105  to a forwardmost point of the golf club head  100 . Typically, the forwardmost point is located at the bottom of the strikeface  111  and adjacent the sole  107 . The offset distance  172  can vary for golf club heads within the same set due to different loft angles. Therefore, in order to compare sets of irons, an average is taken of the offset distances  173  of all golf clubs within a set. The average offset for a tour iron set is generally less than 0.140 inch. The average offset for a game-improvement iron set is generally greater than 0.140 inch. The average offset for a set of golf clubs comprising golf club heads similar to club head  100  is less than 0.140 inch. The offset distance  172  of a single golf club head  100  can be between 0.100 inches and 0.160 inches. In some embodiments, the offset distance can be between 0.100 inch and 0.110 inch, 0.110 inch and 0.120 inch, 0.120 inch and 0.130 inch, 0.130 inch and 0.140 inch, 0.140 inch and 0.150 inch, or 0.150 inch and 0.160 inch. 
     An upper portion depth  116  is measured adjacent the top rail  106  and orthogonal to the strikeface  111  from the front  104  to the rear  103 , as shown in  FIG.  4   . The average upper portion depth of a tour iron is generally less than 0.290 inch. The average upper portion depth of a game improvement iron is generally greater than 0.290 inch. The average upper portion depth for a set of golf clubs comprising golf club heads similar to golf club head  100  is less than 0.290 inch, as is characteristic of a set of tour irons. 
     A parameter that is similar between game-improvement and tour irons is the height of the golf club head. As illustrated in  FIG.  2   , the golf club head  100  can each have a maximum height  175  measured along the loft plane  20  from the lead edge axis  35  to the highest point on the top rail  106 . Golf club head  600  can have a similar height golf club head  100 . The maximum height  175  can be between 2.0 inches and 2.5 inches. In some embodiments, the maximum height  175  can be between 2.0 inches and 2.1 inches, 2.1 inches and 2.2 inches, 2.2 inches and 2.3 inches, 2.3 inches and 2.4 inches, and 2.4 inches and 2.5 inches. 
     Table I, below, compares blade length, hosel X, average offset, average upper portion depth, and maximum height of a tour iron versus a game improvement iron. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE I 
               
               
                   
               
               
                   
                   
                   
                 Offset  
                 Upper  
                   
               
               
                   
                   
                   
                 (AVG 
                 Portion Depth 
                   
               
               
                   
                 Blade 
                 Hosel  
                 of All 
                 (AVG of  
                 Maximum 
               
               
                   
                 Length 
                 X 
                 Lofts) 
                 All Lofts) 
                 Height 
               
               
                   
               
             
            
               
                 Tour Iron 
                 &lt;2.8″ 
                 &lt;1.5″ 
                 &lt;0.140″ 
                 &lt;0.290″ 
                 2.0”-2.5” 
               
               
                 Game 
                 &gt;2.8″ 
                 &gt;1.5″ 
                 &gt;0.140″ 
                 &gt;0.290″ 
                 2.0”-2.5” 
               
               
                 Improvement 
               
               
                   
               
            
           
         
       
     
     B. CG and MOI of Golf Club Head 
     In order to accurately understand the benefits of the perimeter weighting of the golf club head  100 , one must consider both the MOI and CG characteristics of the golf club head  100  and the tour size of the golf club head  100 . Although game-improvement irons are known for having high MOT values, they lack other features unique to tour irons. The golf club described herein marries the benefits of a game-improvement iron with a tour iron style. 
     In some embodiments, the CG  60  of the golf club head  100 ,  600  was shifted down and back compared to a flat back tour iron. The CG  60  position of the golf club head  100  can also be measured from the lead edge plane. 
     The CG  60  of the golf club heads  100 ,  600  can be located above the lead edge plane by between 0.380 inch and 0.670 inch. In some embodiments, the CG  60  of the golf club heads  100 ,  600  can be located above the lead edge plane by between 0.400 inch and 0.650 inch, 0.380 inch and 0.400 inch, 0.400 inch and 0.420 inch, 0.420 inch and 0.440, 0.440 inch and 0.460 inch, 0.460 inch and 0.480 inch, 0.480 inch and 0.500 inch, 0.500 inch and 0.520 inch, 0.520 inch and 0.540 inch, 0.540 inch and 0.560 inch, 0.560 inch and 0.580 inch, 0.580 inch and 0.600 inch, 0.600 inch and 0.620 inch, 0.620 inch and 0.640 inch, 0.640 inch and 0.660 inch, or 0.660 inch and 0.670 inch. In other embodiments, the CG  60  can be located above the lead edge plane by 0.380 inch, 0.390 inch, 0.400 inch, 0.410 inch, 0.420 inch, 0.430 inch, 0.440 inch, 0.450 inch, 0.460 inch, 0.470 inch, 0.480 inch, 0.490 inch, 0.500 inch, 0.510 inch, 0.520 inch, 0.530 inch, 0.540 inch, 0.550 inch, 0.560 inch, 0.570 inch, 0.580 inch, 0.590 inch, 0.600 inch, 0.610 inch, 0.620 inch, 0.630 inch, 0.640 inch, 0.650 inch, 0.660 inch, or 0.670 inch. 
     As described above, the golf club heads  100  and  600  described herein can comprise light weight inserts  140 ,  440 , and  640  in the center of the golf club heads. These weights can be added to the perimeter of the golf club heads  100  and  600  without greatly changing the overall weight of the golf club heads  100 ,  600 , but does allow for a shifting of the CG  60 , and raising MOI. This perimeter weighting can come in the form of toe weights, a tip weight, or added body material around the perimeter. The compact nature of the golf club heads  100  and  600  leads to material properties playing a greater role in MOI improvement than structural properties. As described above, the MOI about the CG  60  and about the x-axis  30 , Ixx, can range from 78 to 120 gram square inches. The MOI about the CG  60  and about the y-axis  40 , Iyy, can range from 310 to 466 gram square inches. These MOI values can apply to golf club head  100  and  600 . These MOI values can further apply to any embodiment having insert  140 ,  640 , or multi-material insert  440 . 
     IV. Methods 
     As shown in  FIG.  24   , a method  500  of manufacturing the golf club head  100  is described herein. The method comprises providing each component  510 , placing the insert in the body  520 , swedging (swagging) the faceplate onto the body  530 , laser welding a boundary between the faceplate and the body  540 , and cleaning up the final product through grinding and polishing. In some embodiments of the method  500 , the method  500  can consist of steps  510 ,  520 ,  530  and  550 . 
     Step  510  can comprise providing at least a body  110 , an insert  140  or a multi-material insert  440 , and a faceplate  155  as components for the golf club head  100 . In some embodiments, providing the body  110  can consist of one or more of: forging, casting, forming by additive manufacturing, machining, or any other suitable method for forming the body  110 . Step  510  can comprise forming the body  110  as a unitary piece. 
     In some embodiments, providing the insert  140  can consist of one or more of: forging, casting, forming by additive manufacturing, machining, or any other suitable method for forming the body  140 . In some embodiments, the insert  140  or a portion of the multi-material insert  440  is molded by pouring a resin into a fiber reinforcing structure to form an elastomeric matrix composite. The insert  140  can be formed as a unitary piece having a uniform density or as multiple pieces having different densities. In some embodiments, having the multi-material insert  440 , the insert  440  can be formed into a single unit or can be placed into the cavity  120  in two separate portions. 
     In some embodiments providing the multi-material insert  440  comprises (1) providing a first portion  450  of the insert  440 , (2) providing a second portion  460  of the insert  440 , and (3) joining the first and second portions  450 ,  460  of the insert  440 . Providing the first portion  450  of the insert  440  can comprise molding the first portion  440 . Providing the second portion  460  of the insert  440  can comprise casting, forging, stamping, die casting, or other means of providing the second portion  460 . In some embodiments, the sub-steps of (1) providing the second portion  460  and (2) joining the first and second portions  450 ,  460  are combined when the first portion  450  is molded and joined to the second portion  460 . In some embodiments, the insert  440  may be sanded, ground, or polished before being inserted into the cavity  120  of the golf club head  100 . 
     In some embodiments, forming the faceplate  155  can consist of forging, casting, machining, forming by additive manufacturing, or otherwise forming the faceplate  155 . In some embodiments, forming the faceplate  155  can comprise machining, casting, or forging a variable thickness geometry into the faceplate  155 . 
     In some embodiments, step  510  of method  500  can further comprise providing a toe weight, a tip weight, and/or a toe screw weight. In these embodiments, step  510  further comprises welding the toe weight  161  into a toe cavity  114  of the body  110 . In other embodiments, the toe weight  161  can be swedged (swaged), adhered, or otherwise secured onto the body  610 . For embodiments of the golf club head  100  further comprising a toe screw weight, the toe screw weight can be screwed into the golf club head in step  510 ,  520 ,  530 , or  550 . 
     Step  520  of the method  500  comprises placing the insert  140  in a cavity  120  of the body  110 . The insert  140  is inserted through a front opening of the cavity  120  at a front  104  of the body  110 . In some embodiments, this step  520  involves applying adhesive, such as epoxy, to the cavity  120  of the body  110  and to the insert  140  to secure the insert  140  into the body  110 . In some embodiments, this step  520  involves applying one more tape layers, such as tape layer  150 , to the cavity  120  before placing the insert  140  into the cavity. The one or more tape layers, such as tape layer  150 , can form a strong and durable connection between the insert  140  and the cavity  120  of the body  110 . Furthermore, the use of tape can reduce the possibility for rattling and other undesirable quality issues. In some embodiments, various other methods of fastening the insert  140  to the body  110  are combined for maximum security. Not all embodiments of the method  500  require adhering or securing the insert  140  into the cavity  120 . 
     Step  530  of method  500  comprises securing the faceplate  155  onto the body  110 . The faceplate  155  is placed within the indentation  142 . By placing the faceplate  155  in the indentation  142 , the faceplate  155  is positioned so that it covers the insert  140  and the cavity  120  of the body  110 . Step  530  can further comprise swedging (swagging) the faceplate  155  onto the body  110  so that the faceplate  155  is embedded in the indentation  142  on the front  104  of the body  110 . In this way, the insert  140  is held within the golf club head  100  and completely isolated from the outside of the golf club head  100 . In other embodiments, the faceplate  155  is adhered, press-fit, or otherwise secured to the body. 
     Some golf club heads are manufactured by methods including co-forging (also known as integrated forging) and joining individually cast parts by high temperature and high applied pressure. These methods apply high temperatures which affect multiple components of the golf club head, including any inserts. For example, the co-forging process occurs at temperatures between 700 and 1000 degrees Celsius. The melting point of some aluminum alloys falls between 650 and 680 degrees Celsius. Thus, for an aluminum insert, co-forging would ruin the integrity of the aluminum material. The insert  140 ,  440 , the body  110 , and the faceplate  155  are not co-forged together, because co-forging can lead to high temperatures which can compromise the insert  140 ,  440 . 
     Furthermore, TIG welding a faceplate onto the golf club head could also impart high temperatures to the golf club head which could compromise the insert. The possible materials for a low-density center of an iron-type golf club head are significantly limited due to conventional manufacturing processes. The golf club head  100  can be manufactured with a wide variety of insert materials, because the manufacturing process does not place the final assembly under high temperatures. Additionally, some insert materials described herein, such as a thermoplastic composite, simply cannot be co-forged with a metal body material. The manufacturing method  500  described herein allows the insert  140 ,  440  to be formed from any suitable material without requiring that the material be able to be co-forged with the body  110 . 
     Step  530  and step  540 , described below, both employ low-heat methods of securing the faceplate  155  to enclose the insert  140  within the cavity  120 . Swedging, laser welding, and other low temperature methods of securing the faceplate  155  allow the insert  140  or  440  to comprise a wide variety of materials in order to fine-tune acoustics, feel, and weighting. The low-head methods of steps  530  and  540  further allow versatility in the design, such as the use of adhesives and/or tape around the cavity  120  to reduce unwanted rattling and vibration. 
     Step  540  comprises laser welding a boundary between the faceplate  155  and the body  110 . The process of step  540  is also referred to as surface fusion treatment. After the faceplate  155  is swedged onto the body  110  in step  530 , the overlapping region or boundary between the faceplate  155  and the body  110  is laser welded. This laser welding process blends the metal materials of the faceplate  155  and the body  110  without creating a deep heat affected zone (hereafter “HAZ”). Laser welding the boundary eliminates any cracks or seams between the faceplate  155  and the body  110 . In some embodiments, the golf club head  100  is finished with a coating in step  550 , as described below. If the boundary has even minute cracks or seams, the coating can seep into the seams and cause quality issues. Laser welding the boundary in step  540  eliminates this manufacturing issue. 
     Step  540 , described above, can be conducted without compromising the integrity of the materials within the cavity  120  because the HAZ depth is between 0.03 inch and 0.08 inch, which can be less than the thickness  112  of the faceplate  155 . In some embodiments, the HAZ depth can be less than 0.08 inch, less than 0.07 inch, less than 0.06 inch, less than 0.05 inch, less than 0.04 inch, or less than 0.03 inch. In some embodiments, the HAZ depth can be 0.03 inch, 0.04 inch, 0.05 inch, 0.06 inch, 0.07 inch, or 0.08 inch. Laser welding heats the insert and other cavity fillers, such as tape layer(s), to a temperature that is lower than a melting temperature of the insert material. The heat imparted to the golf club head  100  during step  540  does not compromise any of the materials sealed within the cavity  120 . 
     In step  550  of the method  550 , the golf club head  100  is cleaned up through grinding and polishing. Grinding is used to create a smooth surface on the strikeface  111  of the golf club head  100 . Furthermore, this step  550  can comprise polishing the surface of the golf club head  100  after grinding. In some embodiments, grooves are ground into the strikeface  111  of the faceplate  155 , and the strikeface  111  is thereafter polished. No step in the manufacturing method  500  comprises co-forging with different materials. 
     As shown in  FIG.  25   , a method  700  of manufacturing a golf club head, similar to golf club head  600 , comprises providing at least a body  610 , an insert material, a faceplate  655 , welding or swedging the faceplate  655  onto the body  610 , injecting an insert material into the cavity  620  of the body  610 , and polishing and cleaning the golf club head  600 . 
     In step  710 , the body  610  can be forged, cast, or formed by additive manufacturing. The faceplate  655  can be forged, cast, or formed by additive manufacturing. In a variation of the manufacturing process  700 , the strikeface  655  is integrally formed as part of the body  610  rather than being separately formed as a faceplate  655  and welded or swedged onto a front opening of the body  610 . In some embodiments, step  710  of method  700  further comprises providing a toe weight  661 , a tip weight  650 , and/or a toe screw weight  662 . In these embodiments, step  710  further comprises welding the toe weight  661  into a toe cavity  614  of the body  610 . In other embodiments, the toe weight  661  can be swedged (swaged), adhered, or otherwise secured onto the body  610 . For embodiments of the golf club head  600  further comprising a toe screw weight  662 , the toe screw weight  662  can be screwed into the golf club head in step  710 ,  720 ,  730 , or  750 . 
     Furthermore, in step  710  of method  700 , an opening wall  782  defining a rear opening  680  can either be formed into the body  610  or can be cut into the rear  603  of the body  610  after the body  610  is formed. Step  710  can further comprise polishing or finishing the opening wall  782  of the rear  603 . 
     Step  720  comprises placing the faceplate  655  within an indentation  642  of the body. The faceplate  655  is welded, swedged (swaged), or otherwise secured to the body  610 . The body  610  and strikeplate  655  form a cavity  620 . After the faceplate  655  is secured to the body  610 , the only opening to the cavity  620  is the rear opening  680  of the body  610 , as illustrated for the embodiment of  FIGS.  14 - 23   . In some embodiments, step  720  of method  700  can further comprise a laser welding or surface fusion treatment process, similar to that described in step  540  of method  500  above. 
     In step  730 , the insert material is injected, in liquid form, into the cavity  620  through the opening  60  in the rear. The cavity  620  of the body  610  serves as a mold for the injected material. In some embodiments, the injection molding process results in the insert material bonding to the surfaces of the cavity  620 . To inject the material into the cavity  620  under pressure, an injection apparatus must be sealed to the mouth of the rear opening  680 . The planar surface surrounding the rear opening  680  in the upper portion  608  of the golf club head  600  allows a good seal to be made between the injection apparatus and the body  610  of the golf club head  600 . In some embodiments, where the insert  640  only partially fills the cavity  620 , the injection apparatus is configured to further form a seal with a portion of the cavity  620  to prevent the material from filling the entire cavity  620 . 
     Step  740  of the method  700 , the golf club head  600  is cleaned up through grinding and polishing. Grinding is used to create a smooth surface on the strikeface  611  of the golf club head  600 . Furthermore, this step  740  can comprise polishing the surface of the golf club head  600  after grinding. In some embodiments, grooves are ground into the strikeface  611  of the faceplate  655 , and the strikeface  611  is thereafter polished. 
     A method of making some embodiments of the golf club head  600 , resembles the method  500  more closely than the method  700  described above. In some embodiments, a method of forming the golf club head  600  wherein the golf club head  600  comprises a metal insert  640 , would require placing the insert  640  within the cavity  640  prior to swedging on the faceplate  655 . 
     V. Examples 
     Example 1: Measurement of Golf Club Head 
     The golf club head  100 , as described above, was measured using several different parameters. The included the blade length  173 , hosel-x length  174 , the offset distance  172 , the upper portion depth  116 , and the maximum height  175 . These values were compared to a game improvement iron and are both shown in Table II, below. Both the golf club head  100  and the game improvement iron that were measured were 7-irons, having a roughly equivalent loft angle. 
     
       
         
           
               
             
               
                 TABLE II 
               
             
            
               
                   
               
               
                 Parameters for Example 1. 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Blade 
                   
                   
                 Upper  
                 Maximum 
               
               
                   
                 Length 
                 Hosel X 
                 Offset 
                 Portion Depth 
                 Height 
               
               
                   
               
               
                 Golf club head 
                 2.727” 
                 1.345” 
                 0.085″ 
                 0.250” 
                 2.040” 
               
               
                 100 
                   
                   
                   
                   
                   
               
               
                 Game 
                 2.802” 
                 1.630” 
                 0.175” 
                 0.315” 
                 2.045” 
               
               
                 Improvement 
               
               
                   
               
            
           
         
       
     
     Example 2: Moment of Inertia (MOI) Comparison and Center of Gravity (CG) Comparison 
     A test has been conducted to compare the MOI of a traditional tour iron head to golf club heads  100  described above. The traditional tour iron head used in this comparison test is identical in size and headweight to the sample golf club head. Thus, this test isolated the MOI as a variable, to provide an accurate comparison of the performance of the sample over the traditional tour iron head. The test produced an Ixx value of roughly 108 gram square inches for the sample club head and an Ixx value of roughly 103 gram square inches for the traditional tour iron head. Therefore, the MOI around the x-axis  30  is approximately 4.8% higher in the sample club head. The test produced an Iyy value of roughly 413 gram square inches for the sample club head and an Iyy value of roughly 398 gram square inches for the traditional tour iron head. Therefore, the MOI around the y-axis  40  is approximately 3.7% higher in the sample club head. This test shows that the lightweight insert for the golf club head  100  provides an improvement in MOI without altering the size or weight of the golf club head  100 . 
     Additionally, a comparison was done between five club heads: (1) an iron similar to golf club head  600 , having an opening in the rear and an insert formed from TPC; (2) an iron similar to golf club head  600 , having an opening in the rear and an insert formed from aluminum; (3) an iron similar to golf club head  100 , having an enclosed cavity filled with a TPC insert; (4) an iron similar to golf club head  100 , having an enclosed cavity filled with an aluminum insert; and (5) a solid steel club head having a similar overall club head volume to the golf club heads described herein. Measurements were taken using computer aided design (CAD) models of each golf club head. Table III below summarizes the MOI data collected. Table IV below summarizes the CG data collected. 
     
       
         
           
               
             
               
                 TABLE III 
               
             
            
               
                   
               
               
                 MOI Comparison Data for Example 2 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Mass 
                   
                   
                 MOIxx 
                 MOIyy 
               
               
                 Club Head 
                 (g) 
                 MOIxx 
                 MOIyy 
                 efficiency 
                 efficiency 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 (1) Filled with  
                 265.0 
                 97.4 
                 414.4 
                 0.368 
                 1.564 
               
               
                 TPC (opening in 
                   
                   
                   
                   
                   
               
               
                 rear) 
                   
                   
                   
                   
                   
               
               
                 (2) Filled with  
                 278.0 
                 100.0 
                 421.8 
                 0.360 
                 1.517 
               
               
                 Aluminum 
                   
                   
                   
                   
                   
               
               
                 (opening in rear) 
                   
                   
                   
                   
                   
               
               
                 (3) Filled with  
                 254.1 
                 96.1 
                 410.3 
                 0.378 
                 1.615 
               
               
                 TPC (enclosed 
                   
                   
                   
                   
                   
               
               
                 cavity) 
                   
                   
                   
                   
                   
               
               
                 (4) Filled with  
                 265.0 
                 98.0 
                 415.5 
                 0.370 
                 1.568 
               
               
                 Aluminum 
                   
                   
                   
                   
                   
               
               
                 (enclosed cavity) 
                   
                   
                   
                   
                   
               
               
                 (5) Solid Steel 
                 314.0 
                 106.6 
                 438.8 
                 0.340 
                 1.398 
               
               
                   
               
            
           
         
       
     
     Since MOI is a function of distance from the CG and mass, the MOI will reflect changes in the overall mass of the golf club head. Therefore, to accurately compare club head MOI, the difference in total mass of the golf club head must be accounted for. In order to illustrate the efficiency of the MOI across the compared golf club heads, the MOI was divided by the mass of the golf club head to arrive at an MOI efficiency value. The MOI efficiency value of golf club heads can be compared, independent of mass, to show how the structure and localized weighting of the golf club heads affects the MOI. Therefore, although the MOI values in both the x-axis  30  and the y-axis  40  directions were higher for the solid steel golf club head (5) than for the low-density insert golf club heads (1) through (4), the MOI efficiency of the solid steel golf club head (5) was lower than the MOI efficiency of golf club heads (1) through (4). Therefore, the golf club heads (1) through (4) with low-density inserts are more forgiving than a golf club head lacking the low-density insert  140 ,  440 ,  460  of the golf club head  100 ,  600  described herein. 
     As can be seen from Table III, the golf club heads (1) through (4) with low-density inserts have MOI efficiencies in the x-axis  30  direction of 5.9% to 11.2% higher than solid steel golf club head (5). As can be seen from Table III, the club heads (1) through (4) with low-density inserts have MOI efficiencies in the y-axis  40  direction of 8.5% to 15.5% higher than solid steel golf club head (5). 
     In addition to increasing the MOI, lowering of the CG can also benefit golf club head performance. The golf club heads  100 ,  600  described herein comprise a lower CG  60  than an equivalent solid steel iron having a similar shape to golf club heads  100  and  600 . Lower CG is desirable in tour irons because shots are easier to shape when the CG is lower. For golf club head  600 , the lowering of the CG is due in part to the elimination of high-density body material by inclusion of the opening  680  in the rear  603 . 
     
       
         
           
               
             
               
                 TABLE IV 
               
             
            
               
                   
               
               
                 CG Comparison Data for Example 2 
               
            
           
           
               
               
               
               
               
            
               
                 Golf Club Head 
                 Mass (g) 
                 CGx 
                 CGy 
                 CGz 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 (1) Filled with TPC 
                 265.0 
                 0.037 
                 0.528 
                 −0.510 
               
               
                 (opening in rear) 
                   
                   
                   
                   
               
               
                 (2) Filled with 
                 278.0 
                 0.022 
                 0.532 
                 −0.517 
               
               
                 Aluminum (opening in 
                   
                   
                   
                   
               
               
                 rear) 
                   
                   
                   
                   
               
               
                 (3) Filled with TPC 
                 254.1 
                 0.055 
                 0.566 
                 −0.525 
               
               
                 (enclosed cavity) 
                   
                   
                   
                   
               
               
                 (4) Filled with 
                 265.0 
                 0.040 
                 0.562 
                 −0.528 
               
               
                 Aluminum (enclosed 
                   
                   
                   
                   
               
               
                 cavity) 
                   
                   
                   
                   
               
               
                 (5) Solid Steel 
                 314.0 
                 −0.012 
                 0.543 
                 −0.539 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG.  1   , the CGy is measured in the y-axis  40  direction (vertical) and upward from the lead edge axis  35 . The CGx is measured horizontally along the lead edge axis  35  with the origin at the y-axis  40 , such that the CG is closer to the heel  102  when the CGx value is positive. The CGz is measured rearward, horizontally along the z-axis  50  from the lead edge axis  35 . The CGy value is lower in golf club heads 1 and 2 than in golf club heads 3-5. This shows that the golf club heads having the opening in the rear of the body (similar to golf club head  600 , described above) have a desirably lower CG. The CG is 2.06% lower in club head 2 than in steel club head 5. The CG is 2.84% lower in golf club head 1 than in steel golf club head 5, indicating that the low-density TPC insert results in an even better CG placement than it&#39;s aluminum insert counterpart (golf club head 2). 
     The comparison data in Tables III and IV further illustrates the strengths of the enclosed cavity embodiments and the rear opening embodiments. Although all embodiments of the invention (comparison golf club heads (1) through (4)) show improvements over the solid club head (5), both the enclosed cavity embodiments (comparison golf club heads (3) and (4)) and the rear opening embodiments (comparison golf club heads (1) and (2)) provide unique benefits. The comparison data shows that the MOI efficiency in both the x-axis  30  direction and the y-axis  40  direction is higher in the enclosed cavity club heads (3) and (4) than in the club heads (1), (2), and (5), as shown in the MOI efficiency columns of Table II. This suggests that the enclosed cavity embodiments, similar to golf club heads  100  described herein or comparison club heads (3) and (4), are more forgiving than embodiments having an opening in the rear, such as golf club head  600  or comparison club heads (1) and (2). However, embodiments with a rear opening  680  in the body  610  have lower CG values than the embodiments having an enclosed cavity, as shown in the CGy column of Table IV. 
     Example 3: Center of Gravity Flat Back Versus Inflection Seam Back Comparison 
     In addition to MOI and feel, the location of the CG of a golf club head affects performance. In particular, the CG location affects the amount of torque that is imparted to the golf club head upon impact with a golf ball. By lowering the CG, the arm between the force applied by the golf ball and the CG is lessened, since the golf ball is typically struck with a lower portion of the strikeface. This shortened arm between the applied force and the CG results in lower torque and improved launch characteristics upon impact with a golf ball. Therefore, in order to provide the golfer with the best possible experience, the golf club head described herein comprises a low CG. 
     To illustrate the how the uniform depth of the upper portions  108 ,  608  of the golf club head  100 ,  600  leads to a lower CG  60 , a comparison was done between a golf club head, similar to golf club heads  100  and  600 , and a comparison golf club head having a varying depth from its top rail to its sole. The comparison golf club head has a planar rear stretching from its top rail to its sole. In order to provide an accurate illustration, the comparison golf club head and the golf club head similar to  100  and  600  were both modeled with the same total mass. The results of the comparison are outlined in Table IV below. 
     
       
         
           
               
             
               
                 TABLE IV 
               
             
            
               
                   
               
               
                 CG Comparison Data for Example 3 
               
            
           
           
               
               
               
               
               
            
               
                 Golf Club Head 
                 Mass (g) 
                 CGx 
                 CGy 
                 CGz 
               
               
                   
               
               
                 Golf club head similar to 
                 261.0 
                 0.044 
                 0.569 
                 −0.528 
               
               
                 100 and 600 (rear with 
                   
                   
                   
                   
               
               
                 inflection point &amp; uniform 
                   
                   
                   
                   
               
               
                 upper portion depth) 
                   
                   
                   
                   
               
               
                 Comparison golf club head 
                 261.0 
                 0.047 
                 0.608 
                 −0.542 
               
               
                 (planar rear) 
               
               
                   
               
            
           
         
       
     
     As shown in Table IV, the CGy value, which is measured along the vertical y-axis  40 , is significantly lower for the golf club head similar to  100  and  600 . Specifically, the golf club head similar to  100  and  600  comprises a CGy 0.039 inch lower than the comparison golf club head. This shows that the uniform depth of the upper portion  108 ,  608  above the inflection point  130 ,  630 , lowers the CG, providing better launch and spin characteristics and higher ball speed. 
     Furthermore, the CGz value, is measured along the z-axis  50 , wherein rearward of the CG  60  is negative and forward of the CG  60  is positive. The CG  60  of the golf club head similar to  100  and  600  is closer to the front of the golf club head. 
     Example 4: Feel and Sound 
     Part of the appeal of tour irons is their compact profile and sleek aesthetic design. Furthermore, forged golf club heads are perceived by many golfers to perform better than cast club heads. Therefore, it is critical that a tour iron satisfy these expectations. Golfers especially enjoy the sound and feel of forged tour irons over other types of irons. In golf the “feel” of the golf club head, as perceived by a golfer, plays a big role in the golfer&#39;s performance. The “feel” is generally affected by weighting, materials, acoustics, and the thickness of the strikeface. Most golfers agree that tour irons provide a solid feel that is absent from many other types of irons. The golf club heads described herein exhibit a solid feel and acoustic quality that equals if not exceeds existing tour irons. 
     A survey has been conducted to quantify the feel of a sample tour iron, having a golf club head similar to the golf club head  100  described herein. Twenty golfers participated in the survey and compared their experiences with the sample iron to their experiences with a traditional tour iron. After using both the sample and the traditional iron, survey participants were asked the following question for each iron: “How satisfied are you with the impact experience (feel/sound) that this iron provides?” A majority of the players preferred the impact experience of the sample tour iron over the traditional tour iron. 
     Finally, the quality and durability of the iron is critical to lasting performance. The strikeface  111  and  611  is engineered to withstand, alone, the stresses placed on it by striking a golf ball. However, the inclusion of the thermoplastic composite insert  140 ,  640 , the fully metal insert  140 ,  640 , or the multi-material insert  440  gives the golf club head an additionally solid feel and improves the acoustic quality of the golf club head over similar hollow-bodied golf club heads. The faceplate  155 ,  655  can improve the quality and durability of the golf club head by ensuring that the insert  140 ,  640  remains secured inside the golf club head at all times. 
     By combining and balancing CG placement, perimeter weighting for MOI, and a tour iron look and feel, the golf club head  100 ,  600  described herein fills a need in the art for an iron type club head that marries the reliability of a game-improvement iron with the elegance of a tour iron. 
     The golf club heads  100  and  600  described herein functions as tour type golf club heads. They offer a high MOI while remaining smaller than typical game-improvement irons. These multi-material golf club heads  100  and  600  offer a compact product with exceptional forgiveness. 
     While  FIGS.  1 - 23    depict specific embodiments of golf club heads, the disclosure of embodiments is intended to be illustrative of the scope of the present disclosure and is not intended to be limiting. It is intended that the scope of the present disclosure shall be limited only to the extent required by the appended 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), golf equipment related to the methods, apparatus, and/or 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 methods, apparatus, and/or articles of manufacture described herein may be advertised, offered for sale, and/or sold as conforming or non-conforming golf equipment. The methods, apparatus, and/or articles of manufacture described herein are not limited in this regard. 
     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 stated in such claim. 
     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. 
     Clause 1: A golf club head comprising a faceplate, a body, and an insert; the body comprising an upper portion, a lower portion, a sole, a rear, and a top rail; wherein: the faceplate and a portion of the body define a striking surface of the golf club head; the faceplate, the sole, the rear, and the top rail enclose a cavity; the rear comprises an inflection seam; the sole rests on a ground plane; a loft plane is tangential to the faceplate and intersects the ground plane; a centerplane, perpendicular to the loft plane, and coincident with a centerpoint of the striking surface; the upper portion is bounded by the top rail and the inflection seam; the upper portion comprises a height measured along the centerplane from the top rail to the inflection seam, in a direction parallel to the loft plane; the lower portion comprises a height measured along the centerplane from the sole to the inflection seam, in a direction parallel to the loft plane; the height of the upper portion and the height of the lower portion have a ratio of between 9:8 and 6:11; the upper portion comprises a first depth and the lower portion comprises a second depth, wherein the depths are measured perpendicular to the loft plane from the striking surface to an outer surface of the rear, along the centerplane; the first depth is constant and is less than the second depth; the sole, the rear, the top rail, and the faceplate enclose a cavity; the insert is received in the cavity, and the insert complements 90% or more of the cavity; the faceplate comprises a first material of a first density; the body comprises a second material of a second density; the insert comprises a third material of a third density; and the third density is less than the first and second densities. 
     Clause 2: The golf club head of clause 1, further comprising: a heel and a toe; an x-axis, extending in a heel-to-toe direction, parallel to the striking surface, and coincident with a center of gravity of the club head; a y-axis, orthogonal to the ground plane and coincident with the center of gravity; wherein: a moment of inertia, Ixx, measured about the x-axis ranges between 78 gram square inches and 120 gram square inches; and a moment of inertia, Iyy, measured about the y-axis ranges between 310 gram square inches and 466 gram square inches. 
     Clause 3: The golf club head of clause 3, wherein the third density is between 2.4 and 5.0 g/cc. 
     Clause 4: The golf club head of clause 3, wherein the third material comprises a material selected from the group consisting of: aluminum and titanium. 
     Clause 5: The golf club head of clause 1, wherein the first density is between 2.6 and 8.7 g/cc and the second density is between 7.7 and 8.1 g/cc. 
     Clause 6: The golf club head of clause 5, wherein the first material comprises a material selected from the group consisting of: a steel-based material, a titanium-based material, an aluminum alloy, or a titanium alloy; the second material comprises a material selected from the group consisting of: a steel-based material or a steel alloy. 
     Clause 7: The golf club head of clause 1, further comprising: a total mass; a toe weight; wherein: the body further comprises: a toe cavity; the toe cavity receives the toe weight; and the toe weight comprises a mass between 5% and 45% of the total mass of the club head. 
     Clause 8: The golf club head of clause 1, wherein a ratio of the first depth to a maximum of the second depth is between 1:3 and 4:5. 
     Clause 9: The golf club head of clause 1, further comprising: a center of gravity; and a lead edge axis, parallel to the ground plane, extending in a heel-to-toe direction, and coincident with a point on the centerplane that is lowest on the striking surface; a lead edge plane, parallel to the ground plane and coincident with the lead edge axis; a y-axis, orthogonal to the ground plane, and coincident with the center of gravity; and wherein the center of gravity of the golf club head is located between 0.380 inch and 0.670 inch above the lead edge plane. 
     Clause 10: The golf club head of clause 1, further comprising: a heel and a toe; a cylindrical hosel integral to the body; a hosel reference plane, parallel to a front edge of the cylindrical hosel, when viewed from a toe side view; a hosel axis, defined as the central axis of the cylindrical hosel; a lead edge axis, parallel to the ground plane, extending in a heel-to-toe direction, and coincident with a point on the centerplane that is lowest on the striking surface; a hosel-X distance, measured from the intersection of the lead edge axis with the centerplane to the intersection of the lead edge axis with the hosel axis, when viewed from a front view, wherein the hosel-X distance is less than 1.5 inches; and an offset distance, measured as the minimum distance between the lead edge axis and the hosel reference plane; wherein the offset distance between 0.05 inch and 0.27 inch. 
     Clause 11: The golf club head of claim 1, further comprising: a heel and a toe; and a blade length, measured in a heel-to-toe direction from an edge of the striking surface in the heel to an outermost point on the toe; wherein the blade length is less than 2.8 inches. 
     Clause 12: The golf club head of claim 1, further comprising a high density tape disposed between the insert and the faceplate. 
     Clause 13: The golf club head of claim 1, wherein: the body further comprises an indentation; the indentation abuts a periphery of the cavity; an area of a rear surface of the faceplate contacts the insert; a remaining area of the rear surface of the faceplate contacts the indentation. 
     Clause 14: A method of forming a golf club head comprising the following steps: (1) providing a faceplate comprising a first material of a first density; (2) providing a body, comprising a second material of a second density, an upper portion, a lower portion, a sole, a rear, and a top rail; wherein: the faceplate and a portion of the body define a striking surface of the golf club head; the rear comprises an inflection seam; the sole rests on a ground plane; a loft plane is tangential to the faceplate and intersects the ground plane; a centerplane, extending in a top rail-to-sole direction, and coincident with a centerpoint of the striking surface; the upper portion is bounded by the top rail and the inflection seam; the upper portion comprises a height measured along the centerplane from the top rail to the inflection seam, in a direction parallel to the loft plane; the lower portion comprises a height measured along the centerplane from the sole to the inflection seam, in a direction parallel to the loft plane; the height of the upper portion and the height of the lower portion have a ratio of between 9:8 and 6:11; the upper portion comprises a first depth and the lower portion comprises a second depth, wherein the depths are measured perpendicular to the loft plane from the striking surface to an outer surface of the rear, along the centerplane; the first depth is constant and is less than the second depth; the sole, the rear, and the top rail define a cavity; (3) providing an insert, comprising a third material of a third density, wherein the third density is less than the first and second densities; and (4) placing the insert within the cavity; where after the insert complements 90% or more of the cavity; and (5) securing the faceplate to the body, wherein the faceplate further defines and encloses the cavity. 
     Clause 15: The method of forming a golf club head of clause 14, wherein securing the faceplate to the body in step (5) comprises: swedging the faceplate onto the body; laser welding a boundary between the faceplate and the body. 
     Clause 16: The method of forming a golf club head of clause 15, wherein laser welding the boundary of the faceplate and the body comprises creating a heat affected zone comprising a depth of less than 0.070 inch. 
     Clause 17: The method of forming a golf club head of clause 15, wherein: the golf club head further comprises: a heel and a toe; an x-axis, extending in a heel-to-toe direction, parallel to the striking surface, and coincident with a center of gravity of the club head; a y-axis, orthogonal to the ground plane and coincident with the center of gravity; wherein: a moment of inertia, Ixx, measured about the x-axis ranges between 78 gram square inches and 120 gram square inches; and a moment of inertia, Iyy, measured about the y-axis ranges between 310 gram square inches and 466 gram square inches. 
     Clause 18: A method of forming a golf club head of clause 14, further comprising placing a tape layer onto the insert between steps (4) and (5), wherein the tape layer is sandwiched between the insert and the faceplate upon completion of step (5). 
     Clause 19: A method of forming a golf club head of clause 14, wherein: the method further comprises forming a cylindrical hosel integral to the body; the golf club head further comprises: a heel and a toe; a hosel reference plane, parallel to a front edge of the cylindrical hosel, when viewed from a toe side view; a hosel axis, defined as the central axis of the cylindrical hosel; a lead edge axis, parallel to the ground plane, extending in a heel-to-toe direction, and coincident with a point on the centerplane that is lowest on the striking surface; a hosel-X distance, measured from the intersection of the lead edge axis with the centerplane to the intersection of the lead edge axis with the hosel axis, when viewed from a front view, wherein the hosel-X distance is less than 1.5 inches; and an offset distance, measured as the minimum distance between the lead edge axis and the hosel reference plane; wherein the offset distance between 0.05 inch and 0.27 inch. 
     Clause 20: A method of forming a golf club head of clause 14, wherein: the golf club head comprises a total mass; the body further comprises a toe cavity; and the method further comprising: forming a toe weight, the toe weight comprising a mass between 5% and 45% of the total mass of the golf club head; and securing the toe weight within the toe cavity. 
     Clause 21: A golf club head comprising a faceplate, a body, and an insert; the body comprising an upper portion, a lower portion, a sole, a rear, and a top rail; wherein: the faceplate and a portion of the body define a striking surface of the golf club head; the faceplate, the sole, the rear, and the top rail enclose a cavity; the rear comprises an inflection seam; the sole rests on a ground plane; a loft plane is tangential to the faceplate and intersects the ground plane; a centerplane, perpendicular to the loft plane, and coincident with a centerpoint of the striking surface; the upper portion is bounded by the top rail and the inflection seam; the upper portion comprises a height measured along the centerplane from the top rail to the inflection seam, in a direction parallel to the loft plane; the lower portion comprises a height measured along the centerplane from the sole to the inflection seam, in a direction parallel to the loft plane; the height of the upper portion and the height of the lower portion have a ratio of between 9:8 and 6:11; the upper portion comprises a first depth and the lower portion comprises a second depth, wherein the depths are measured perpendicular to the loft plane from the striking surface to an outer surface of the rear, along the centerplane; the first depth is constant and is less than the second depth; the sole, the rear, the top rail, and the faceplate enclose a cavity; the insert is received in the cavity, and the insert complements 90% or more of the cavity; the insert comprises a first portion and a second portion; the faceplate comprises a first material of a first density; the body comprises a second material of a second density; the first portion of the insert comprises a third material of a third density; the second portion of the insert comprises a fourth material of a fourth density; and the third density is less than the first, second, and fourth densities. 
     Clause 22: The golf club head of clause 21, wherein the second portion of the insert does not contact the faceplate. 
     Clause 23: The golf club head of clause 22, wherein the second portion of the insert is wholly located in the lower portion of the body. 
     Clause 24: The golf club head of clause 21, wherein the fourth density is greater than the first and second densities. 
     Clause 25: The golf club head of clause 21, wherein a ratio of the first depth to a maximum of the second depth is between 1:3 and 4:5. 
     Clause 26: The golf club head of clause 21, further comprising: a center of gravity; and a lead edge axis, parallel to the ground plane, extending in a heel-to-toe direction, and coincident with a point on the centerplane that is lowest on the striking surface; a lead edge plane, parallel to the ground plane and coincident with the lead edge axis; a y-axis, orthogonal to the ground plane, and coincident with the center of gravity; and wherein the center of gravity of the golf club head is located between 0.380 inch and 0.670 inch above the lead edge plane. 
     Clause 27: The golf club head of clause 21, further comprising: a heel and a toe; a cylindrical hosel integral to the body; a hosel reference plane, parallel to a front edge of the cylindrical hosel, when viewed from a toe side view; a hosel axis, defined as the central axis of the cylindrical hosel; a lead edge axis, parallel to the ground plane, extending in a heel-to-toe direction, and coincident with a point on the centerplane that is lowest on the striking surface; a hosel-X distance, measured from the intersection of the lead edge axis with the centerplane to the intersection of the lead edge axis with the hosel axis, when viewed from a front view, wherein the hosel-X distance is less than 1.5 inches; and an offset distance, measured as the minimum distance between the lead edge axis and the hosel reference plane; wherein the offset distance between 0.05 inch and 0.27 inch. 
     Clause 28: The golf club head of clause 21, further comprising: a heel and a toe; and a blade length, measured in a heel-to-toe direction from an edge of the striking surface in the heel to an outermost point on the toe; wherein the blade length is less than 2.8 inches. 
     Clause 29: The golf club head of clause 21, further comprising a high density tape disposed between the insert and the faceplate. 
     Clause 30: The golf club head of clause 21, wherein the first depth is less than 0.290 inch. 
     Clause 31: The golf club head of clause 21, wherein the third density is between 2.4 and 5.0 g/cc. 
     Clause 32: The golf club head of clause 31, wherein: the third material comprises a material selected from the group consisting of: aluminum and titanium; and the fourth material comprises tungsten. 
     Clause 33: The golf club head of clause 21, further comprising: a total mass; a toe weight; wherein: the body further comprises: a toe cavity; the toe cavity receives the toe weight; and the toe weight comprises a mass between 5% and 45% of the total mass of the club head. 
     Clause 34: The golf club head of clause 21, further comprising: a heel and a toe; an x-axis, extending in a heel-to-toe direction, parallel to the striking surface, and coincident with a center of gravity of the club head; a y-axis, orthogonal to the ground plane and coincident with the center of gravity; wherein: a moment of inertia, Ixx, measured about the x-axis ranges between 78 gram square inches and 120 gram square inches; and a moment of inertia, Iyy, measured about the y-axis ranges between 310 gram square inches and 466 gram square inches. 
     Clause 35: A method of forming a golf club head comprising the following steps: (1) providing a faceplate comprising a first material of a first density; (2) providing a body, comprising a second material of a second density, an upper portion, a lower portion, a sole, a rear, and a top rail; wherein: the faceplate and a portion of the body define a striking surface of the golf club head; the rear comprises an inflection seam; the sole rests on a ground plane; a loft plane is tangential to the faceplate and intersects the ground plane; a centerplane, extending in a top rail-to-sole direction, and coincident with a centerpoint of the striking surface; the upper portion is bounded by the top rail and the inflection seam; the upper portion comprises a height measured along the centerplane from the top rail to the inflection seam, in a direction parallel to the loft plane; the lower portion comprises a height measured along the centerplane from the sole to the inflection seam, in a direction parallel to the loft plane; the height of the upper portion and the height of the lower portion have a ratio of between 1:1 and 2:1; the upper portion comprises a first depth and the lower portion comprises a second depth, wherein the depths are measured perpendicular to the loft plane from the striking surface to an outer surface of the rear, along the centerplane; the first depth is constant and is less than the second depth; the sole, the rear, and the top rail define a cavity; (3) providing an insert, comprising a first portion and a second portion; wherein: the first portion comprises a third material of a third density; the second portion comprises a fourth material of a fourth density; the third density is less than the first, second, and fourth densities; (4) placing the insert within the cavity; where after the insert fills 90% or more of the cavity; and (5) securing the faceplate to the body, wherein the faceplate further defines and encloses the cavity. 
     Clause 36: A method of forming a golf club head of clause 35, wherein securing the faceplate to the body in step (5) comprises: swedging the faceplate onto the body; heat treating (or laser welding) a boundary between the faceplate and the body. 
     Clause 37: The method of forming a golf club head of clause 35, wherein laser welding the boundary of the faceplate and the body comprises creating a heat affected zone comprising a depth of less than 0.070 inch. 
     Clause 38: The method of forming a golf club head of clause 35, wherein: the golf club head further comprises: a heel and a toe; an x-axis, extending in a heel-to-toe direction, parallel to the striking surface, and coincident with a center of gravity of the club head; a y-axis, orthogonal to the ground plane and coincident with the center of gravity; wherein: a moment of inertia, Ixx, measured about the x-axis ranges between 78 gram square inches and 120 gram square inches; and a moment of inertia, Iyy, measured about the y-axis ranges between 310 gram square inches and 466 gram square inches. 
     Clause 39: A method of forming a golf club head of clause 35, further comprising placing a tape layer onto the insert between steps (4) and (5), wherein the tape layer is sandwiched between the insert and the faceplate upon completion of step (5). 
     Clause 40: A method of forming a golf club head of clause 35, wherein the first portion and the second portion of the insert are integrally formed prior to step (4). 
     Clause 41: A golf club head comprising: a faceplate, a body, and an insert; the body comprising an upper portion, a lower portion, a sole, a rear, and a top rail; wherein: the faceplate and a portion of the body define a striking surface of the golf club head; the faceplate, the sole, the rear, and the top rail define a cavity; the rear comprises an inflection seam and a wall defining an opening; the opening wall is above the inflection seam, and comprises: a top wall adjacent the top rail, a bottom wall adjacent the inflection seam, a toe wall, and a heel wall; the sole rests on a ground plane; a loft plane is tangential to the faceplate and intersects the ground plane; a centerplane, perpendicular to the loft plane, and coincident with a centerpoint of the striking surface; a projected area of the opening, taken parallel to the loft plane, comprises an area between 25% and 50% of a projected area of the entire rear; the upper portion is bounded by the top rail and the inflection seam; the upper portion comprises a height measured along the centerplane from the top rail to the inflection seam, in a direction parallel to the loft plane; the lower portion comprises a height measured along the centerplane from the sole to the inflection seam, in a direction parallel to the loft plane; the height of the upper portion and the height of the lower portion have a ratio of between 1:1 and 2:1; the upper portion comprises a first depth and the lower portion comprises a second depth, wherein the depths are measured perpendicular to the loft plane from the striking surface to an outer surface of the rear, along the centerplane; the first depth is constant and is less than the second depth; the sole, the rear, the top rail, and the faceplate enclose a cavity; the insert is received in the cavity, and the insert complements up to 90% of the cavity; the faceplate comprises a first material of a first density; the body comprises a second material of a second density; the insert comprises a third material of a third density; and the third density is less than the first and second densities.