Patent Publication Number: US-11383139-B2

Title: Golf club head or other ball striking device with weighted body member

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of U.S. patent application Ser. No. 16/513,551, now U.S. Pat. No. 10,799,777, filed on Jul. 16, 2019, which is a continuation of U.S. patent application Ser. No. 15/983,001, now U.S. Pat. No. 10,369,432, filed May 17, 2018, which is a continuation of U.S. patent application Ser. No. 15/493,507, now U.S. Pat. No. 9,993,702, filed Apr. 21, 2017, which is a continuation of U.S. patent application Ser. No. 14/621,762, now U.S. Pat. No. 9,630,072, filed Feb. 13, 2015, which is a continuation of U.S. patent application Ser. No. 13/485,329, now U.S. Pat. No. 8,968,114, filed May 31, 2012. This application claims priority to and the benefit of all of the above listed applications, which are incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The invention relates generally to ball striking devices, such as golf clubs and heads. Certain aspects of this invention relate to golf clubs and golf club heads having a body member connected to a face member, with the body member having strategic weighting. 
     BACKGROUND 
     Golf is enjoyed by a wide variety of players—players of different genders, and players of dramatically different ages and skill levels. Golf is somewhat unique in the sporting world in that such diverse collections of players can play together in golf outings or events, even in direct competition with one another (e.g., using handicapped scoring, different tee boxes, etc.), and still enjoy the golf outing or competition. These factors, together with increased golf programming on television (e.g., golf tournaments, golf news, golf history, and/or other golf programming) and the rise of well known golf superstars, at least in part, have increased golfs popularity in recent years, both in the United States and across the world. 
     Golfers at all skill levels seek to improve their performance, lower their golf scores, and reach that next performance “level.” Manufacturers of all types of golf equipment have responded to these demands, and recent years have seen dramatic changes and improvements in golf equipment. For example, a wide range of different golf ball models now are available, with some balls designed to fly farther and straighter, provide higher or flatter trajectory, provide more spin, control, and feel (particularly around the greens), etc. 
     Being the sole instrument that sets a golf ball in motion during play, the golf club also has been the subject of much technological research and advancement in recent years. For example, the market has seen improvements in golf club heads, shafts, and grips in recent years. Additionally, other technological advancements have been made in an effort to better match the various elements of the golf club and characteristics of a golf ball to a particular user&#39;s swing features or characteristics (e.g., club fitting technology, ball launch angle measurement technology, etc.). 
     Despite the various technological improvements, golf remains a difficult game to play at a high level. For a golf ball to reliably fly straight and in the desired direction, a golf club should meet the golf ball square (or substantially square) to the desired target path. Moreover, the golf club should meet the golf ball at or close to a desired location on the club head face (i.e., on or near a “desired” or “optimal” ball contact location) to reliably fly straight, in the desired direction, and for a desired distance. Off-center hits that deviate from squared contact and/or are located away from the club&#39;s desired ball contact location may tend to “twist” the club face when it contacts the ball, thereby sending the ball in the wrong direction, often imparting undesired hook or slice spin, and/or robbing the shot of distance. Accordingly, club head features that can help a user keep the club face square with the ball, such as by reducing twisting, would tend to help the ball fly straighter and truer, in the desired direction, and often with improved and/or more reliable distance. 
     Various golf club heads have been designed to improve a golfer&#39;s accuracy by assisting the golfer in squaring the club head face at impact with a golf ball. When the club face is not square at the point of engagement, the golf ball may fly in an unintended direction, may follow a route that curves left or right, ball flights that are often referred to as “pulls,” “pushes,” “draws,” “fades,” “hooks,” or “slices,” and/or may exhibit more boring or climbing trajectories. The distance and direction of ball flight can also be significantly affected by the spin imparted to the ball by the impact with the club head. Additionally, the spin of the ball can change the behavior of the ball as it rolls and bounces after impact with the ground. Various speeds and directions of spin on the ball can be a product of many factors, including the point of impact, the direction of the club head upon impact, the degree of twisting of the club head upon impact, and the location of the center of gravity of the club head. 
     The energy and velocity transferred to the ball by a golf club also may be related, at least in part, to the flexibility of the club face at the point of contact, and can be expressed using a measurement called “coefficient of restitution” (or “COR”). The maximum COR for golf club heads is currently limited by the USGA at 0.83. Generally, a club head will have an area of highest COR response relative to other areas of the face, which imparts the greatest energy and velocity to the ball, and this area is typically positioned at or near the geometric center of the face. In one example, the area of highest response may have a COR that is equal to the prevailing USGA limit which is currently 0.83 and may change over time. However, because golf clubs are typically designed to contact the ball at or around the center of the face, off-center hits may result in less energy being transferred to the ball, decreasing the distance of the shot. 
     The weighting and weight distribution of a golf club head may also influence the energy and velocity transferred to the ball by the impact, as well as the moment of inertia and the center of gravity of the club head. The moment of inertia of the head can be increased, for example, by distributing a greater amount of weight around the perimeter of the head. This, in turn, can reduce the amount of twisting of the club head that occurs on off-center hits, and increase the distance and accuracy of shots on off-center hits. Likewise, the location of the center of gravity of the head can be influenced by the weight distribution of the head. Generally, the desired contact area of the face is aligned with the center of gravity of the head. However, it may be desirable to shift the location of the center of gravity of the head, such as to adjust for common off-center hitting patterns by a golfer, or to produce a certain shot characteristic (e.g., to induce a hook, slice, draw, fade, etc.). Additionally, different clubs having different loft angles can benefit from different weighting, such as a set of iron-type golf clubs having different centers of gravity. For example, a center of gravity that is lower and/or farther backward can produce higher loft and lower spin on the shot, while a center of gravity that is higher and/or farther forward may produce lower loft, greater distance, and higher spin on the shot and/or greater control, each of which may be desirable in certain clubs or for certain golfers. Accordingly, club head features that can permit the weighting and weight distribution of the head to be adjusted or customized may provide improved performance in several ways. 
     The present device and method are provided to address the problems discussed above and other problems, and to provide advantages and aspects not provided by prior ball striking devices of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings. 
     BRIEF SUMMARY 
     The following presents a general summary of aspects of the invention in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a general form as a prelude to the more detailed description provided below. 
     Aspects of the invention relate to ball striking devices, such as golf clubs, with a head that includes a face having a ball striking surface configured for striking a ball and a body connected to the face and extending rearward from the face. A face member forms the face, and a body member is connected to the face member and extends rearward from the face member to form at least a portion of the body. The body member and/or the face member is formed at least partially of a polymer material, and has a doped portion containing a doping material dispersed within the polymer material. The doping material may have a different density than the polymer material, such that the doped portion has a different density than the portions of the head not containing the doping material. The face member may be formed primarily of a metallic material in one embodiment. Additionally, the head may be completely or partially coated with a particulate metallic nano-coating material. 
     According to one aspect, the polymer material of the body member includes at least one of the following materials: acrylonitrile butadiene styrene, polyamide alloys, high density polyethylene (HDPE), styrene ethylene butylene styrene block copolymer, thermoplastic polyurethane, other polyurethanes, rubber materials, silicones, and other polymers and copolymers, and combinations thereof. The doping material includes at least one of the following particulate materials: tungsten, stainless steel, brass, copper, lead, etc., as well as non-metals such as various oxides, sulfates, etc. and combinations thereof, or any other material or combination of such materials having one or more desired properties, 
     According to another aspect, the body member further may comprise a fiber reinforcing material engaged with the polymer material and reinforcing the polymer material. 
     According to a further aspect, the face member can be connected to the body member in many different configurations. In one embodiment, the face member and the body member may have complementary mating structures connecting the face member to the body member. For example, one of the face member and the body member may have a projection and the other may have a receiver that receives the projection to connect the face member to the body member. The face member and the body member may have a dovetail mating structure, with appropriate projection(s) and recess(es). The projection may be a ridge extending around at least a portion of the periphery of the face member, and the recess may be a complementarily-shaped channel extending around at least a portion of the periphery of the body member. A bonding material (e.g., adhesives, cements, etc.) may additionally or alternately be used. 
     According to yet another aspect, the face member and the body member are connected by forming the body member in connection to the face member in a co-molding process. 
     According to a still further aspect, the body member has a plurality of doped portions, each containing the doping material dispersed within the polymer material, and the doped portions are positioned in different locations. 
     Additional aspects of the invention relate to an iron-type golf club head that includes a face member forming an iron-type face defined by a plurality of peripheral edges and having a ball striking surface configured for striking a ball, and a body member connected to the rear surface of the face member and extending rearward from the face member, with the body member forming at least a portion of an iron-type body extending rearwardly from the peripheral edges of the face. The face member is formed primarily of a metallic material, and the body member is formed at least partially of a polymer material. The body member has a doped portion containing a doping material dispersed within the polymer material. The doping material has a different density than the polymer material, such that the doped portion has a different density than the portions of the body member not containing the doping material. Any aspects described above also may be incorporated into this club head structure. 
     According to another aspect, the face member is joined to the body member around at least a portion of a periphery of the face member. 
     Further aspects of the invention relate to a set of iron-type golf clubs that includes six iron-type golf clubs, each having an iron-type golf club head that includes a face defined by a plurality of peripheral edges, with the face having a ball striking surface configured for striking a ball and an inner surface opposite the ball striking surface, and a body connected to the face and extending rearward from the peripheral edges of the face. The body is formed at least partially of a polymeric material having a doped portion containing a doping material dispersed within the polymer material. The doping material has a different density than the polymer material, such that the doped portion has a different density than a portion of the body not containing the doping material. The six golf clubs have different loft angles that increase in a sequence, such that the loft angle of each of the golf clubs is about 5° greater than a previous golf club in the sequence. Such a set of clubs may also include one or more clubs of a different type, such as one or more wood-type clubs. 
     According to one aspect, the six golf clubs include a first club having a loft angle of about 20°, a second club having a loft angle of about 25°, a third club having a loft angle of about 30°, a fourth club having a loft angle of about 35°, a fifth club having a loft angle of about 40°, and a sixth club having a loft angle of about 45°. 
     According to another aspect, the set further includes a seventh club, such as a pitching wedge having a loft angle of about 50°, a gap wedge having a loft of about 55°, a lob wedge having a loft of about 60° or 65°, or another wedge or longer iron club. 
     According to a further aspect, the set of golf clubs may have differently or progressively weighted heads. For example, at least one of the six golf club heads has the doped portion located in a different location relative to the doped portion of at least one other of the six golf club heads. As another example, each of the six golf club heads has the doped portion located in a different location relative to the doped portions of each of the others of the six golf club heads. A set of differently-weighted clubs may be progressively weighted, such as by progressively moving the center of gravity of the club head top-to-bottom and/or heel-to-toe as the clubs become progressively longer or shorter. 
     Still further aspects of the invention relate to methods that may be used in connection with a provided face member formed primarily of a metallic material. The face member forms a golf club face defined by a plurality of peripheral edges and having a ball striking surface configured for striking a ball and a rear surface located rearwardly from the ball striking surface. The face member is positioned in communication with a tool, such that at least a portion of the rear surface of the face member is in communication with the tool. Then, a polymer material is introduced into contact with the tool such that the polymer material contacts at least a portion of the tool and contacts the rear surface of the face member. The polymer material forms a body member connected to the rear surface of the face member when the polymer material hardens or solidifies. The face member and the body member combine to form a golf club head comprising the face and a body extending rearwardly from the face. Such methods may be considered co-molding methods. 
     According to one aspect, the tool is a mold having a mold cavity. The polymer material is introduced into the mold cavity such that the polymer material fills at least a portion of the mold cavity and contacts the rear surface of the face member. The polymer material may be introduced into the mold cavity by injection of the polymer material in flowable form. In one example, the polymer material forms around an interior surface of the mold cavity and is spaced from at least a portion of the rear surface of the face member, such that the face member and the body member combine to define an interior cavity within the club head. 
     According to another aspect, a doping material is positioned proximate the tool prior to introducing the polymer material into contact with the tool, such that the doping material becomes embedded within the polymer material when the polymer material is introduced into contact with the tool. The doping material has a different density than the polymer material, such that the doped portion has a different density than the portions of the body member not containing the doping material. 
     According to a further aspect, the face member has a mating structure and the polymer material forms the body member with complementary mating structure. The mating structure may include a projection on the face member, such that the polymer material forms around the projection to form a receiver that receives the projection to connect the face member to the body member. In one example, the face member has a dovetail mating structure and the body member has a complementary dovetail mating structure. 
     According to yet another aspect, a fiber reinforcing material is positioned proximate the tool prior to introducing the polymer material into contact with the tool, such that the fiber reinforcing material becomes embedded within the polymer material when the polymer material is introduced into contact with the tool. 
     According to a still further aspect, the polymer material contains a fiber reinforcing material that is introduced into contact with the tool along with the polymer material, such that the fiber reinforcing material is embedded within the polymer material after the polymer material forms the body member. In one example, the polymer material and the fiber reinforcing material may be formed together as a prepreg. In this configuration, the polymer material and the fiber reinforcing material can be introduced into contact with the tool by placing the prepreg into contact with the tool. In another example, the polymer material may be in flowable form and the fiber reinforcing material may be particles dispersed throughout the flowable material. In this configuration, the polymer material and the fiber reinforcing material can be introduced into contact with the tool by injecting the polymer material into contact with the tool along with the dispersed fiber reinforcing material. 
     Other aspects of the invention relate to golf clubs that include a golf club head as described above and a shaft connected to the head, or a set of golf clubs including at least one golf club having a head as described above. 
     Other features and advantages of the invention will be apparent from the following description taken in conjunction with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To allow for a more full understanding of the present invention, it will now be described by way of example, with reference to the accompanying drawings in which: 
         FIG. 1  is a front view of an illustrative embodiment of an iron-type ball striking device according to aspects of the present invention; 
         FIG. 2  is a front view of an illustrative embodiment of a head of the ball striking device of  FIG. 1 ; 
         FIG. 3  is a rear view of the head of  FIG. 2 ; 
         FIG. 4  is a cross-section view of the head of  FIG. 2 , taken along lines  4 - 4  of  FIG. 2 ; 
         FIG. 4A  is a cross-section view of the head as shown in  FIG. 4 , having a coating material disposed on an outer surface thereof; 
         FIG. 5A-5I  show illustrative embodiments of iron-type ball striking heads as illustrated in  FIG. 4 , having doped portions positioned in different locations; 
         FIG. 6  is a cross-sectional view of one illustrative embodiment of a mold and process capable of forming a head of a ball striking device as shown in  FIG. 2 ; 
         FIG. 7  is a cross-sectional view of the mold and process of  FIG. 6 , shown after a polymer material is introduced into a cavity of the mold; 
         FIG. 7A  is a cross-sectional view of another illustrative embodiment of a mold and process capable of forming a head of a ball striking device; 
         FIG. 8  is a cross-section view of a second illustrative embodiment of an iron-type ball striking head suitable for use with the ball striking device of  FIG. 1 , having a dovetail-type mating connecting structure; 
         FIG. 8A  is a rear view of a face member of the head of  FIG. 8 ; 
         FIG. 9  is a cross-section view of a third illustrative embodiment of an iron-type ball striking head suitable for use with the ball striking device of  FIG. 1 , having a mating connecting structure; 
         FIG. 10  is a rear view of a fourth illustrative embodiment of an iron-type ball striking head suitable for use with the ball striking device of  FIG. 1 ; 
         FIG. 11  is a cross-section view of the head of  FIG. 10 , taken along lines  11 - 11  of  FIG. 10 ; 
         FIG. 12  is a rear view of a fifth illustrative embodiment of an iron-type ball striking head suitable for use with the ball striking device of  FIG. 1 ; 
         FIG. 13  is a cross-section view of the head of  FIG. 12 , taken along lines  13 - 13  of  FIG. 12 ; 
         FIG. 14  is a cross-section view of a sixth illustrative embodiment of an iron-type ball striking head suitable for use with the ball striking device of  FIG. 1 ; 
         FIG. 15A-15F  is a schematic view of an illustrative embodiment of a set of iron-type golf club heads, with the heads labeled  FIG. 15A-15F  in sequential order of increasing loft angle; 
         FIG. 16  is a schematic view of an iron-type club head, illustrating changes in position of a doped portion for club heads corresponding to the set of  FIG. 15A-15F ; 
         FIG. 17  is a rear view of one embodiment of the iron-type ball striking head of  FIGS. 12 and 13 ; 
         FIG. 18  is a rear view of another embodiment of the iron-type ball striking head of  FIGS. 12 and 13 ; and 
         FIG. 19  is a of a further embodiment of the iron-type ball striking head of  FIGS. 12 and 13 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of various example structures according to the invention, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various example devices, systems, and environments in which aspects of the invention may be practiced. It is to be understood that other specific arrangements of parts, example devices, systems, and environments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. Also, while the terms “top,” “bottom,” “front,” “back,” “side,” “rear,” and the like may be used in this specification to describe various example features and elements of the invention, these terms are used herein as a matter of convenience, e.g., based on the example orientations shown in the figures or the orientation during typical use. Additionally, the term “plurality,” as used herein, indicates any number greater than one, either disjunctively or conjunctively, as necessary, up to an infinite number. Nothing in this specification should be construed as requiring a specific three dimensional orientation of structures in order to fall within the scope of this invention. Also, the reader is advised that the attached drawings are not necessarily drawn to scale. 
     The following terms are used in this specification, and unless otherwise noted or clear from the context, these terms have the meanings provided below. 
     “Ball striking device” means any device constructed and designed to strike a ball or other similar objects (such as a hockey puck). In addition to generically encompassing “ball striking heads,” which are described in more detail below, examples of “ball striking devices” include, but are not limited to: golf clubs, putters, croquet mallets, polo mallets, baseball or softball bats, cricket bats, tennis rackets, badminton rackets, field hockey sticks, ice hockey sticks, and the like. 
     “Ball striking head” means the portion of a “ball striking device” that includes and is located immediately adjacent (optionally surrounding) the portion of the ball striking device designed to contact the ball (or other object) in use. In some examples, such as many golf clubs and putters, the ball striking head may be a separate and independent entity from any shaft or handle member, and it may be attached to the shaft or handle in some manner. 
     The terms “shaft” and “handle” are used synonymously and interchangeably in this specification, and they include the portion of a ball striking device (if any) that the user holds during a swing of a ball striking device. 
     “Integral joining technique” means a technique for joining two or more pieces so that the pieces effectively become a single, integral piece, including, but not limited to, irreversible joining techniques, such as adhesively joining, cementing, and welding (including brazing, soldering, or the like), where separation of the joined pieces cannot be accomplished easily and/or without structural damage to at least one of the pieces. 
     In general, aspects of this invention relate to ball striking devices, such as golf club heads, golf clubs, putter heads, putters, and the like. Such ball striking devices, according to at least some examples of the invention, may include a ball striking head and a ball striking surface. In the case of a golf club, the ball striking surface is a substantially flat surface on one face of the ball striking head (although, in some structures, the face may include some curvature, e.g., known as “bulge” and/or “roll”). Some more specific aspects of this invention relate to iron-type golf clubs and golf club heads, including long irons, short irons, wedges, etc. Alternately, some aspects of this invention may be practiced with hybrid clubs, chippers, and the like, or wood-type golf clubs and the like. 
     According to various aspects of this invention, the ball striking device may be formed of one or more of a variety of materials, such as metals (including metal alloys), ceramics, polymers, composites (including fiber-reinforced composites), and wood, and may be formed in one of a variety of configurations, without departing from the scope of the invention. In one illustrative embodiment, some or all components of the head, including the face and at least a portion of the body of the head, are made of metal. It is understood that the head may contain components made of several different materials, including carbon-fiber and other components. Additionally, the components may be formed by various forming methods. For example, metal components (such as titanium, aluminum, titanium alloys, aluminum alloys, steels (including stainless steels), and the like) may be formed by forging, molding, casting, stamping, machining, and/or other known techniques. In another example, composite components, such as carbon fiber-polymer composites, can be manufactured by a variety of composite processing techniques, such as prepreg processing, powder-based techniques, mold infiltration, and/or other known techniques. 
     The various figures in this application illustrate examples of ball striking devices according to this invention. When the same reference number appears in more than one drawing, that reference number is used consistently in this specification and the drawings refer to the same or similar parts throughout. 
     At least some examples of ball striking devices according to this invention relate to golf club head structures, including heads for wood-type golf clubs, such as drivers, as well as long iron clubs (e.g., driving irons, zero irons through five irons), short iron clubs (e.g., six irons through pitching wedges, as well as sand wedges, lob wedges, gap wedges, and/or other wedges), hybrid clubs, and putters. Such devices may include a one-piece construction or a multiple-piece construction. Example structures of ball striking devices according to this invention will be described in detail below in conjunction with  FIG. 1 , which illustrates an example of a ball striking device  100  in the form of an iron-type golf club, in accordance with at least some examples of this invention. 
       FIG. 1  illustrates a ball striking device  100  in the form of a golf iron, in accordance with at least some examples of this invention, and illustrative embodiments of heads  102 , et seq., of ball striking devices  100  of this type and methods of making them are shown in  FIGS. 2-15 . The golf club head  102  of  FIG. 1  may be representative of any iron-type golf club head in accordance with examples of the present invention. As shown in  FIGS. 1-4 , the ball striking device  100  includes a ball striking head  102  and a shaft  104  connected to the ball striking head  102  and extending therefrom. The ball striking head  102  of the ball striking device  100  of  FIGS. 1-2  has a face  112  connected to a body  108 , with a hosel  109  extending therefrom. Any desired hosel and/or head/shaft interconnection structure may be used without departing from this invention, including conventional hosel or other head/shaft interconnection structures as are known and used in the art, or an adjustable, releasable, and/or interchangeable hosel or other head/shaft interconnection structure such as those shown and described in U.S. Pat. No. 6,890,269 dated May 10, 2005, in the name of Bruce D. Burrows, U.S. Published Patent Application No. 2009/0011848, filed on Jul. 6, 2007, in the name of John Thomas Stites, et al., U.S. Published Patent Application No. 2009/0011849, filed on Jul. 6, 2007, in the name of John Thomas Stites, et al., U.S. Published Patent Application No. 2009/0011850, filed on Jul. 6, 2007, in the name of John Thomas Stites, et al., and U.S. Published Patent Application No. 2009/0062029, filed on Aug. 28, 2007, in the name of John Thomas Stites, et al., all of which are incorporated herein by reference in their entireties. 
     As shown in  FIGS. 2-4 , the golf club head  102  includes a body member  108 , a face  112 , and a hosel  109  extending from the body  108  for attachment of the shaft  104 . For reference, the head  102  generally has a top  116 , a bottom or sole  118 , a heel  120  proximate the hosel  109 , a toe  122  distal from the hosel  109 , a front  124 , and a back or rear  126 . The shape and design of the head  102  may be partially dictated by the intended use of the device  100 . The heel portion  120  is attached to and/or extends from the hosel  109  (e.g., as a unitary or integral one piece construction, as separate connected elements, etc.). In the embodiment shown in  FIGS. 2-4 , the face  112  and the hosel  109  are formed as a single, integral piece, such as by casting, forging, etc. to form a face member  140  as described below. In another embodiment, the face  112  and the hosel  109  may be formed of two or more separate pieces that are connected together by an integral joining technique or another joining technique. It is understood that in each embodiment described herein, the face  112  and hosel  109  may be integrally formed as a single piece, or formed of separate pieces. In other applications, such as for a different type of golf club, the head may be designed to have different dimensions and configurations. 
     The face  112  is located at the front  124  of the head  102 , and has an outer surface  110 , as well as an inner surface  111  located opposite the outer surface  110 . The face  112  is defined by a plurality of peripheral edges, including a top edge  113 , a bottom edge  115 , a heel edge  117 , and a toe edge  119 . The face  112  also has a plurality of face grooves  121  on the ball striking surface  110 . For reference purposes, the portion of the face  112  nearest the top face edge  113  and the heel  120  of the head  102  is referred to as the “high-heel area”; the portion of the face  112  nearest the top face edge  113  and toe  122  of the head  102  is referred to as the “high-toe area”; the portion of the face  112  nearest the bottom face edge  115  and heel  120  of the head  102  is referred to as the “low-heel area”; and the portion of the face  112  nearest the bottom face edge  115  and toe  122  of the head  102  is referred to as the “low-toe area”. Conceptually, these areas may be recognized and referred to as quadrants of substantially equal size (and/or quadrants extending from a geometric center of the face  112 ), though not necessarily with symmetrical dimensions. For at least some types of club heads, the face  112  may include some curvature in the top to bottom and/or heel to toe directions (e.g., bulge and roll characteristics), as is known and is conventional in the art for such clubs. As seen in the illustrative embodiments in  FIGS. 2-5 , the ball striking surface  110  is inclined (i.e., at a loft angle), to give the ball an appreciable degree of lift and spin when struck. In other illustrative embodiments, the ball striking surface  110  may have a different incline or loft angle, to affect the trajectory of the ball. 
     The body  108  and the face  112  of the golf club head  102  may be constructed from a wide variety of different materials, including materials conventionally known and used in the art, such as steel, titanium, aluminum, tungsten, graphite, polymers, or composites, or combinations thereof. Also, if desired, the club head  102  may be made from any number of pieces (e.g., having a separate face mask, etc.) and/or by any construction technique, including, for example, casting, forging, welding, and/or other methods known and used in the art. 
     The ball striking device  100  may include a shaft  104  connected to or otherwise engaged with the ball striking head  102 , as shown in  FIG. 1 . The shaft  104  is adapted to be gripped by a user to swing the ball striking device  100  to strike the ball. The shaft  104  can be formed as a separate piece connected to the head  102 , such as by connecting to the hosel  109 , as shown in  FIG. 1 . In other illustrative embodiments, at least a portion of the shaft  104  may be an integral piece with the head  102 , and/or the head  102  need not contain a hosel  109  or may contain an internal hosel structure. Still further embodiments are contemplated without departing from the scope of the invention. The shaft  104  may be constructed from one or more of a variety of materials, including metals, ceramics, polymers, composites, or wood. In some illustrative embodiments, the shaft  104 , or at least portions thereof, may be constructed of a metal, such as stainless steel or titanium, or a composite, such as a carbon/graphite fiber-polymer composite. However, it is contemplated that the shaft  104  may be constructed of different materials without departing from the scope of the invention, including conventional materials that are known and used in the art. A grip element  105  may be positioned on the shaft  104  to provide a golfer with a slip resistant surface with which to grasp golf club shaft  104 , as shown in  FIG. 1 . The grip element  105  may be attached to the shaft  104  in any desired manner, including in conventional manners known and used in the art (e.g., via adhesives or cements, threads or other mechanical connectors, swedging/swaging, etc.). 
     In one exemplary embodiment, shown in  FIGS. 3-4 , the head  102  includes a rear cavity  130  located behind the face  112 , which is defined at least partially by the inner surface  111  of the face  112 . As shown in  FIGS. 2-4 , the body  108  further includes a sole body member  131  extending rearward from the bottom edge  115  of the face  112  and defining a portion of the rear cavity  130 . The rear cavity  130  may also be partially defined by peripheral or perimeter walls  133  extending rearward from the peripheral edges of the face  112 , including from the top edge  113 , the heel edge  117 , and the toe edge  119  of the face  112 . It is understood that the sole member  131 , or a portion thereof, may be considered to be a peripheral wall  133  as that term is used herein. The peripheral walls  133  follow the curvilinear contour of the body  108 , and portions of the rear cavity  130  are defined by the peripheral walls  133 , including the sole member  131 . Further, the head  102  of  FIGS. 2-4  includes a rear wall  132  extending upward from the rear of the sole member  131 , and partially defining the rear cavity  130 . In the embodiment shown, the rear wall  132  extends the entire width of the rear cavity  130 , and is connected to the rear of the sole member  131  and the peripheral walls  133  on the heel side  120 , the toe side  122 , and the top side  116  of the head  102 . The rear wall  132  may have a different thickness than other portions of the body member  142 , and in an alternate embodiment, may comprise a thin polymer sheet that may be transparent and may influence impact attenuation and/or acoustic characteristics. In additional embodiments, the head  102  may have a differently configured sole member, cavity, or rear wall, or may not contain some of these components. For example, the features described herein can be used in connection with the embodiments illustrated in  FIGS. 8-15  and other known configurations for club heads, including other iron-type club head configurations, as well as hybrid club heads and wood-type club heads. As described below, the head  402  of  FIGS. 10-11  includes a rear wall  432  that extends completely across the rear cavity  430  of the head  402 , from the peripheral wall  433  on the heel side  420  to the peripheral wall  433  on the toe side  422 , but only extends a portion of the distance from the sole member  431  to the peripheral wall  433  on the top side  416 . Additionally, the head  502  of  FIGS. 12-13  has a rear cavity  532  with no rear wall extending upward from the sole member  531 , and the head  602  of  FIG. 14  has a blade-type configuration with a solid body  608  and no rear cavity. 
     In general, the head  102  is formed of at least two separate pieces, including a face member  140  and a body member  142  connected to the face member  140 . The face member  140  and the body member  142  combine to define the head  102  and features thereof, including the face  112  and the body  108  of the head  102 , as described below. It is understood that each of the face member  140  and/or the body member  142  individually may be formed of multiple pieces, and thus, the head  102  may be formed of two or more pieces connected together. 
     The face member  140  generally includes and defines at least the face  112  of the head  102 , including the ball striking surface  110  and the inner surface  111 . The face member  140  is also understood to have a rear surface  141 , which may include the inner surface  111  of the face  112 . In the embodiment shown in  FIG. 4 , the face member  140  includes the face  112 , as well as wall portions  127  that extend rearwardly on the edges  113 ,  115 ,  117 ,  119  of the face  112  and form at least a part of the peripheral walls  133  (including the sole member  131 ). In other embodiments, such as the embodiments shown in  FIGS. 13-14  and described in greater detail below, the face member  140  does not include the rearwardly-extending wall portions  127 . The face member  140  may be made at least partially of a metallic material, and in one embodiment, at least primarily of a metallic material, including the metallic materials described above. For example, the face member  140  may be formed primarily, or at least partially, of a titanium alloy, a stainless steel alloy, or another material commonly used in forming iron-type club heads, or combinations of such materials. In another embodiment, the face member  140  may be formed primarily, or at least partially, of a polymer material that may include a reinforcing material and/or a doping material, such as the materials described below with respect to the body member  142 . Additionally, in one embodiment, the face member  140  is formed entirely of a single material, and may also be formed as a single piece. Further, the hosel  109  may also be formed of the same material(s), and may be part of an integral single-piece face member  140 . For example, in the embodiment shown in  FIGS. 2-4 , the hosel  109  and the face member  140  are integrally formed as a single piece. In another embodiment, the hosel  109  may be joined to the face member  140  and/or the body member  142 , such as by using an integral joining technique, to form a single, integral piece. 
     The body member  142  is connected to face member  140  and extends rearwardly from the face member  140  to form at least a portion of the body  108  of the club head  102 . In the embodiment shown in  FIGS. 2-4 , the body member  142  is connected to the perimeter portions of the rear surface  141  of the face member  140 . In another embodiment, the body member  142  (or a portion thereof) and the face member  140  (or a portion thereof) may be formed of the same material, and may be formed of a single, integral piece, such as shown in  FIG. 7C . Additionally, as described above, at least some portions of the body member  142  may be spaced from at least some portions of the rear surface  141  of the face member  140  to create a rear cavity  130  behind the face  112  and within the head  102 . In the embodiment of  FIGS. 2-4 , the face member  140  and body member  142  define an enclosed rear cavity  130  that extends from the top  116  to the sole  118  and from the heel  120  to the toe  122  of the head  102 . Further, in this embodiment, the peripheral walls  133 , including the sole member  131 , are formed partially by the rearwardly-extending wall portions  127  of the face member  140  and partially by the body member  142 . In other embodiments, the rear cavity  130  may be at least partially open, such as the rear cavities  430 ,  530  of the heads  402 ,  502  in  FIGS. 10-13 , or may have a different configuration, or the head  102  may have no rear cavity  130  at all, such as the head  602  in  FIG. 14 . 
     The body member  142  may be made from one or more of a variety of materials, and the body member  142  may be made from a different material than the face member  140 . As described above, in some embodiments, the body member  142  and the face member  140  may be completely or partially made from the same material. In one embodiment, the body member  142  and/or the face member  140  is made entirely, primarily, or at least partially from a polymer material. It is understood that a “polymer material” may include blends of different polymers, copolymers, etc. In one embodiment, the body member  142  may also contain non-polymer materials along with the polymer material, such as a reinforced polymer composite material that includes a polymer material and a reinforcing material such as a fiber engaged with the polymer material. Examples of polymer materials that can be used include acrylonitrile butadiene styrene (ABS), polyamide alloys (e.g., polyamide 6, polyamide 6/10, polyamide 6/6), high density polyethylene (HDPE), styrene ethylene butylene styrene block copolymer (SEBS), thermoplastic polyurethane (TPU) or other polyurethane, rubber materials, silicones, and other polymers and copolymers. Examples of reinforcing materials that can be used include carbon/graphite fibers, glass fibers, basalt fibers, boron fibers, liquid crystal polymer fibers (e.g., Vectran) or other polymer-based fibers (e.g. UHMWPE, Kevlar, etc.). The polymer material can be formed using a variety of techniques, such as injection molding or other molding techniques, prepreg processing or other composite processing techniques, or other polymer processing techniques available to those skilled in the art. In one embodiment, the polymer material may be lightweight, and the polymer material may be selected for other properties as well. For example, polymer materials with lower flexibility may be selected for enhanced strength and/or rigidity, or polymer materials with higher flexibility may be selected for sound and/or vibration dampening properties. As another example, polymer materials may be selected for their thermal properties or ease of processing. In another embodiment, the body member  142  may be formed of another material that does not contain any polymer material. Further, like the face member  140 , the body member  142  may be formed of several pieces or a single, integral piece, and may be formed from multiple pieces joined together by an integral joining technique. 
     As illustrated in  FIG. 4A , the head  102  may also include a coating material  160  disposed on at least a portion of the outer surface of the head  102 . The coating material  160  may impart one or more desirable properties to the coated portions of the head  102 , including strength, hardness, visual appearance or other optical properties, frictional properties, wear resistance, corrosion resistance, or other properties. In one embodiment, the coating material  160  is a nano-coating material, such as a fine coating of metallic particles (e.g. nickel, iron, and/or zinc), which may be applied by spraying. This coating material  160  can add structural strength and hardness, particularly to polymer-based components of the head  102 , as well as creating a metallic appearance. The coating material  160  may also help bind different components of the head  102  together, such as the face member  140  and the body member  142 . As shown in  FIG. 4A , the entire outer surface of the head  102  may be coated to create a uniform visual impression. In another embodiment, at least the outer surface of the portion(s) of the head  102  that are formed of the polymer material are coated with the coating material  160 . 
     In the embodiment shown in  FIGS. 2-4 , the body member  142  also contains a doping material that is dispersed throughout a portion of the material of the body member  142 , such as a powder or other particulate material. In general, the doping material has at least one different property from the material of the body member  142  and thereby changes the properties of the body member  142 . In one embodiment, the doping material has a greater density than the material of the body member  142 , so that the area or areas where the doping material is located have a higher density or weight than the other portions of the body member  142 . This allows the weighting and the weight distribution of the body member  142  to be controlled, adjusted, and/or customized. One example of a dense doping material that can be used is tungsten powder, although other dense metals or other materials may be used, including stainless steel, brass, copper, lead, etc., as well as non-metals such as various oxides, sulfates, etc. In one embodiment, at least a portion of the body member  142  is formed of rubber doped with tungsten powder. 
     It is understood that the doping material may include more than one different material substance, and that multiple doped portions may be provided throughout the body member  142 , and, if desired, these multiple doped portions may contain different doping materials. Additionally, in one embodiment, doped or weighted portions having substantially identical sizes, but with densities that vary ten-fold, such as from 1.2-12.0 g/cc, can be created by using different doping materials and/or different volume fractions of doping materials in the doped portions. In other embodiments, further weights and densities can be achieved. In one embodiment, one or more of the doped portions containing the doping material may have a density of 9.0-10.0 g/cc. 
       FIGS. 5A-5I  illustrate different embodiments of club heads  102 A-I that have similar structure to the head  102  of  FIGS. 2-4 , each having a doped portion  144  positioned in different locations.  FIG. 5A  illustrates a head  102 A where the doped portion  144  comprises the entire body member  142 .  FIG. 5B  illustrates a head  102 B where the doped portion  144  comprises the entire face member  140 .  FIG. 5C  illustrates a head  102 C where the doped portion  144  comprises an upper portion of the body member  142 .  FIG. 5D  illustrates a head  102 D where the doped portion  144  comprises a lower portion of the body member  142 .  FIG. 5E  illustrates a head  102 E where the face member  140  comprises a first doped portion  144 A and the body member  142  comprises a second doped portion  144 B, with the first and second doped portions  144 A,B having different doping configurations. For example, the first and second doped portions  144 A,B may have different doping materials, doping materials having different properties, etc.  FIG. 5F  illustrates a head  102 F where the upper portion of the body member  142  comprises a first doped portion  144 A and a lower portion of the body member  142  comprises a second doped portion  144 B, with the first and second doped portions  144 A,B having different doping configurations.  FIG. 5G  illustrates a head  102 G where the doped portion  144  is located within an internal cavity  130  of the head  102 G. The doped portion  144  could be formed along with the head  102 G, such as shown in  FIGS. 6-7  below, or may be an insert that is subsequently placed in the cavity  130 . In the embodiment illustrated in  FIG. 5G , the doped portion  144  is positioned in a lower portion of the internal cavity.  FIGS. 5H and 5I  illustrate heads  102 H and  102 I where the doped portion  144  is a more discrete area of the head  102 H,  102 I and is completely embedded within the body member  142 . 
     In the heads  102 C and  102 I of  FIGS. 5C and 5I , the dense doping material would result in a higher center of gravity relative to the other embodiments and relative to a non-doped head. In the heads  102 D,  102 F,  102 G, and  102 H of  FIGS. 5D, 5F, 5G, and 5H , the dense doped portion  144  would result in a lower center of gravity relative to the other embodiments and relative to a non-doped head. In the heads  102 A and  102 C-I of  FIGS. 5A, and 5C-5I , the dense doped portion  144  would result in a center of gravity that is more rearward relative to the other embodiments and relative to a non-doped head. In the head  102 B of  FIG. 5B , the dense doped portion  144  would result in a center of gravity that is more frontward relative to the other embodiments and relative to a non-doped head. It is understood that the embodiments of  FIGS. 5A-5I  illustrate higher and lower portions of the head  102  being formed with doping material, however in other embodiments, lateral portions of the head may be formed with different weighting through the use of doping material, such as in  FIGS. 17-19 . Thus, a nearly infinite number of weighting configurations are possible by positioning the doped portion  144  in different locations in the body member  142 , including changing the weighting in the heel-to-toe direction as well. In other embodiments, the head  102  may include multiple doped portions  144  that have dispersed doping material. 
     The face and body members  140 ,  142  may be formed and connected in a variety of manners. For example, the face and body members  140 ,  142  may be formed as separate pieces and connected together. In one illustrative embodiment, the face and body members  140 ,  142  can be formed together in a co-molding process, as shown in  FIGS. 6-7 . In the embodiment shown in  FIGS. 6-7 , the face member  140  may be formed using any techniques described herein, prior to the commencement of the co-molding process. In one embodiment, the face member  140  may be formed wholly or primarily of a metallic material. The face member  140  may then be brought into communication with a tool T that is used for forming the body member  142 . In this embodiment, the tool T is a mold having a cavity C that can be used for forming the body member  142 , and the face member  140  is placed into communication with the mold cavity C. At least a portion of the rear surface  141  of the face member  140  may be in communication with (e.g., exposed to the interior of) the cavity C, and in the embodiment shown in  FIG. 6 , the entire rear surface  141  of the face member  140  is positioned within the mold cavity C. Once the face member  140  and the tool T are in position, the body member  142  can be formed using the tool T, such as by introducing a material M into contact with the tool T and the face member  140  to form the body member  142  in connection with the face member  140 . In the embodiment illustrated in  FIG. 7 , the material M is a flowable polymer material that is injected into the mold cavity C through injection port P and fills at least a portion of the cavity C, forming around the cavity C and in contact with the rear surface  141  of the face member  140 . It is understood that the tool T may contain additional structures for forming the flowable material M into the shape of the body member  142 , such as an inflatable bladder, a mold core, etc., or that gravity, fluid pressure, etc. could also be used to shape the flowable material M. The material M can then harden and/or solidify to form the body member  142 . As shown in  FIG. 7 , in this embodiment, the polymer material M forms around the interior surface of the mold cavity C and is spaced from at least a portion of the rear surface  141  of the face member  140 , such that the face member  140  and the body member  142  combine to define the interior cavity  130 . 
     In other embodiments, the material M may be introduced into contact with the tool T in a different manner. For example, the material M may be poured into the mold cavity C, or may be brought into contact with the tool T in a non-flowable form, such as a blank preform, a prepreg, etc. It is understood that as described above, the tool T may contain additional structures for forming the inside of the body member  142 , such as an inflatable bladder, a mold core, etc. A different type of tool T may be used in other embodiments. Further, the tool T is illustrated as a two-piece mold that can be separated or opened in order to bring the face member  140  into communication with the cavity C, although in other embodiments, the tool T may have a single-piece configuration or another multi-piece configuration. 
     The doping material may also be utilized in the process as illustrated in  FIGS. 6-7 . In one embodiment, a doped portion  144  is introduced into the tool T before or after introducing the polymer material M into contact with the tool T, as illustrated schematically in  FIGS. 6-7 . For example, the doped portion  144  may be positioned in contact with the tool T using a two-shot or multi-shot molding technique. In such a technique, a loaded polymer material M′ is first shot into the tool T, or otherwise brought into contact with or placed in the tool T in the appropriate locations, as shown in  FIG. 6 , to form the doped portion  144 . The tool T may have suitable injection control mechanisms and features, as known in the art. Thereafter, a non-doped polymer material M is brought into contact with the tool T to create the rest of the part such as by injection, as shown in  FIG. 7 . The doped material M′ becomes at least partially connected to the polymer material M when the polymer material M is introduced into contact with the tool T, and is thereby at least partially contained or dispersed within a portion of the body member  142  after the body member  142  hardens or solidifies. As shown in this embodiment, the doped material M′ may also be in contact with the face member  140 . The base polymer of the loaded polymer material M′ may be the same or a similar material as the polymer material M, or it may be a different material. 
     In another embodiment, as illustrated in  FIG. 7A , both the face member  140  and the body member  142  (or portions thereof) may be formed by a tool T. For example, as described above, both the face member  140  and the body member  142  may be formed of the same material and may be formed together by injecting the polymer material M into the tool T.  FIG. 7A  illustrates this configuration, and it is understood that at least a portion of the face member  140  and/or the body member  142  may be formed of a doped material M′ as described above. As another example, the face member  140  and the body member  142  may be formed of different polymer materials that are both formed by using the tool T. Either or both of the face member  140  and the body member  142  may include a doped material M′ as described above. 
     In a further embodiment, at least a portion of the face member  140  and/or the body member  142  may be formed of a polymer material M, as shown in  FIGS. 6-7A , and a doping material  144  may subsequently be embedded within the polymer material M. This can be done, for example, by using a pressurization technique. 
     As mentioned above, the co-molding process may also utilize a reinforcing material to reinforce the polymer material M. In one embodiment, a reinforcing material, such as a fiber, may be positioned in contact with or proximate the tool T prior to introducing the polymer material M into contact with the tool T. When the polymer material M is introduced into contact with the tool T, the reinforcing material becomes embedded within the polymer material. In another embodiment, the polymer material M may contain a reinforcing material that is introduced into contact with the tool T along with the polymer material M, such that the fiber reinforcing material is embedded within the polymer material M after the polymer material M forms the body member. For example, the polymer material M and the reinforcing material may be formed together as a prepreg, and the polymer material and the fiber reinforcing material can be introduced into contact with the tool by placing the prepreg into contact with the tool. As another example, the polymer material M may be in flowable form and may have a particulate reinforcing material dispersed throughout the flowable material M. The polymer material and the fiber reinforcing material are introduced into contact with the tool T by injecting the polymer material M into contact with the tool T along with the dispersed fiber reinforcing material. 
     The face member  140  may be connected to the body member  142  through one or more of many different connection configurations. The embodiment shown in  FIGS. 2-4  does not illustrate any specific connecting structure, and the face and body members  140 ,  142  may be connected as depicted in  FIGS. 2-4 , such as by use of a bonding material, as described below. In one embodiment, the face member  140  and the body member  142  of  FIGS. 2-4  have complementary mating structures for connection together. For example, one of the face and body members  140 ,  142  may have a projection and the other may have a complementary recess, cavity, notch, etc., to receive the projection to connect the face and body members  140 ,  142  together. Examples of such structures are described in more detail below in conjunction with  FIGS. 8-9 . As described above, the face member  140  and the body member  142  (or portions thereof) may be formed of a single piece and/or a single material in another embodiment. 
       FIGS. 8-9  illustrate two other embodiments of an iron-type head  202 ,  302 . Many features of the heads  202 ,  302  of  FIGS. 8-9  are similar to the features of the head  102  shown in  FIGS. 2-4 , and such similar features are identified by similar reference numerals in  FIGS. 8-9  using the “2xx” and “3xx” series of reference numerals, respectively. Accordingly, certain features of the heads  202 ,  302  of  FIGS. 8-9  that are already described above may described below using less detail, or may not be described at all. In the embodiment of  FIGS. 8 and 8A , the face and body members  240 ,  242  are connected by a dovetail mating structure  250 . The mating structure  250  includes at least one dovetail projection  252  on the face member  240  that is received in at least one dovetail recess  254  on the body member  242 . The dovetail projections  252  illustrated in  FIGS. 8 and 8A  are located at the ends of the wall portions  227  that extend rearwardly from the face  212 . In this embodiment, the dovetail projection  252  is in the form of a ridge  253  that extends around the periphery of the rear surface  241  of the face member  240 , as illustrated in  FIG. 8A . Likewise, the recess  254  is in the form of a channel that extends around the periphery of the front of the body member  242 . It is understood that the face and body members  240 ,  242  may be connected by the material M of the body member  242  forming around the dovetail projection  252 . That the face and/or body member  240 ,  242  may additionally or alternately contain structure to aid in snapping the components together and/or separating the components. 
     In the embodiment of  FIG. 9 , the face and body members  340 ,  342  are connected by a friction-fit or interference fit mating structure  350 . The mating structure  350  includes at least one projection  352  on the face member  340  that is received in at least one complementary-shaped recess  354  on the body member  342 . The projection  352  illustrated in  FIG. 9  is located at the ends of the wall portions  327  that extend rearwardly from the face  312 , similar to the projection  252  in  FIGS. 8 and 8A . In this embodiment, the projection  352  is in the form of a ridge  353  that extends around the periphery of the rear surface  341  of the face member  340 , similar to the ridge  253  illustrated in  FIG. 8A . Likewise, the recess  354  is in the form of a channel that extends around the periphery of the front of the body member  342 . 
     It is understood that the ridge-projections  252 ,  352  in  FIGS. 8-9  are depicted as a single uninterrupted ridge, but could also be in the form of several smaller ridges that may be disrupted or spaced from each other, or more discrete structures that are farther separated from each other, such as a series of post-like ridges. The channel-recesses  254 ,  354  may be similarly configured. It is understood that the head  202 ,  302  may include any number of projections  252 ,  352  and/or recesses  254 ,  354 . In another embodiment, the orientation of the projection(s) and channel(s) may be transposed, so that the body member  242 ,  342  has a projection or other male-type mating structure and the face member  240 ,  340  has a recess or other female-type mating structure. Optionally, each part  240 ,  242 ,  340 ,  342  may include a mixture of male and female type mating structures. 
     In further embodiments, the face member  240 ,  340  and the body member  242 ,  342  may have additional types of mating connecting structure or other connecting structures. For example, the face and body members  240 ,  340 ,  242 ,  342  may have other mechanical connecting structures, such as lap joints, fasteners, tabs or snap fitting arrangements, including other complementary mating-type structures, and/or may include the use of a bonding material, such as adhesive, cement, welding, brazing, soldering, etc. It is understood that a combination of mechanical connecting structure and bonding material may be used in some embodiments, and that a bonding material may be used with the embodiments in  FIGS. 8-9 . Such complementary mating-type structures may include any of various interlocking structures as well. 
     The complementary mating structures described herein can be utilized in connection with a co-molding method as described above and illustrated in  FIGS. 6-7 . For example, with reference to the mating structure  250  of the head  202  of  FIGS. 8 and 8A , the face member  240  may be inserted into the mold tool T as described above, and the material M of the body member  242  may form around the projection  252 . Thus, the recess  254  may be inherently formed in the process of co-molding the body member  242  with the face member  240 . Other mating structures, such as the mating structure  350  of  FIG. 9 , may also be formed in this manner. 
     Any of the features described above with respect to the embodiments in  FIGS. 2-9  may be used in a wide variety of other golf club designs, including other iron-type golf club head designs such as those shown in  FIGS. 10-14 . For example, the use of doped portions  144 , the connection between the face members  140 ,  240 ,  340  and body members  142 ,  242 ,  342 , and/or the use of the co-molding process that are described above and shown in  FIGS. 2-9  can be incorporated into other types of golf club heads, including the heads  402 ,  502 ,  602  of  FIGS. 10-14 . The embodiments of heads  402 ,  502 ,  602  shown in  FIGS. 10-14  are described in greater detail below. 
       FIGS. 10-11  illustrate one embodiment of a golf club head  402  that may utilize one or more of the various features described above. Many features of the head  402  of  FIGS. 10-11  are similar to the features of the head  102  shown in  FIGS. 2-4 , and such similar features are identified by similar reference numerals in  FIGS. 10-11  using the “4xx” series of reference numerals. Accordingly, certain features of the head  402  of  FIGS. 10-11  that are already described above may described below using less detail, or may not be described at all. In the embodiment shown in  FIGS. 10-11 , the head  402  has a face member  440  that includes the face  412  and wall portions  427  extending rearwardly from the face  412 . The body member  442  is connected to the rear surface  441  of the face member  440 , but covers only the lower portions of the rear surface  441  of the face member  440  and does not cover the entire rear surface  441 . In other words, the body member  442  is connected to the wall portions  427  of the face member  440  at the sole  418 , the heel  420 , and the toe  422 , but is not connected to the face member  440  around the top  416 . Additionally, the head  402  includes a partially-enclosed (or partially-open) rear cavity  430  that is defined by the inner surface  411  of the face  412 , the peripheral walls  433 , and a rear wall  432  that extends upwardly from the sole member  431 . In this embodiment, the rear wall  432  is a part of the body member  442  and extends completely across the rear cavity  430  of the head  402 , from the peripheral wall  433  on the heel side  420  to the peripheral wall  433  on the toe side  422 , but only extends a portion of the distance from the sole member  431  to the peripheral wall  433  on the top side  416 . As with the embodiment shown in  FIGS. 2-4 , no specific connecting structure is shown in the embodiment of  FIGS. 10-11 , however any of the connecting structures described herein may be used to connect the face and body members  440 ,  442  in this embodiment. Likewise, any of the materials and/or forming methods described herein, including the use of doping materials, may be incorporated into this embodiment. 
       FIGS. 12-13  illustrate another embodiment of a golf club head  502  that may utilize one or more of the various features described above. Many features of the head  502  of  FIGS. 12-13  are similar to the features of the head  102  shown in  FIGS. 2-4 , and such similar features are identified by similar reference numerals in  FIGS. 12-13  using the “5xx” series of reference numerals. Accordingly, certain features of the head  502  of  FIGS. 12-13  that are already described above may described below using less detail, or may not be described at all. In the embodiment shown in  FIGS. 12-13 , the head  502  has a face member  540  with a plate-like configuration that includes the face  512 , with no wall portions (e.g.  127 ) extending rearwardly from the face  512 . In this embodiment, the rear surface  541  of the face member  540  may be embodied entirely by the inner surface  511  of the face  512 . The body member  542  is connected to the rear surface  541  of the face member  540 , around the peripheral edges  513 ,  515  of the face  512 . Additionally, in this embodiment, the head  502  has an open rear cavity  530  defined by the inner surface  511  of the face  512  and the peripheral walls  533 , with no rear wall extending upward from the sole member  531 . As with the embodiment shown in  FIGS. 2-4 , no specific connecting structure is shown in the embodiment of  FIGS. 12-13 , however any of the connecting structures described herein may be used to connect the face and body members  540 ,  542  in this embodiment. Likewise, any of the materials and/or forming methods described herein, including the use of doping materials, may be incorporated into this embodiment. 
       FIG. 14  illustrates another embodiment of a golf club head  602  that may utilize one or more of the various features described above. Many features of the head  602  of  FIG. 14  are similar to the features of the head  102  shown in  FIGS. 2-4 , and such similar features are identified by similar reference numerals in  FIG. 14  using the “6xx” series of reference numerals. Accordingly, certain features of the head  602  of  FIG. 14  that are already described above may described below using less detail, or may not be described at all. In the embodiment shown in  FIG. 14 , the head  602  has a face member  640  with a plate-like configuration that includes the face  612 , with no wall portions (e.g.  127 ) extending rearwardly from the face  612 . The body member  642  is connected to the rear surface  641  of the face member  640 , and forms a blade-type head  602  with a solid body  608  and no rear cavity. As with the embodiment shown in  FIGS. 2-4 , no specific connecting structure is shown in the embodiment of  FIG. 14 , however any of the connecting structures described herein may be used to connect the face and body members  640 ,  642  in this embodiment. Likewise, any of the materials and/or forming methods described herein, including the use of doping materials, may be incorporated into this embodiment. In one example structure, the more dense, doped material may be provided around the perimeter to provide at least some of the advantages of perimeter weighted irons while having the aesthetic appearance of blade type irons. 
     In further embodiments, features and techniques described herein, including the use of doped portions  144  may be utilized or incorporated within other types of golf club heads or other ball-striking devices. For example, these features can be used in a wood-type golf club, such as those shown in U.S. Pat. No. 7,993,216, which is hereby incorporated by reference herein in its entirety and made part hereof. 
     Several different embodiments have been described above, including the various embodiments of golf clubs  100  and heads  102 ,  102 A-C,  202 ,  302 ,  402 ,  502 ,  602  and portions thereof described herein. It is understood that any of the features of these various embodiments may be combined and/or interchanged. For example, as described above, various different combinations of face members  140 , et seq. with differently configured body members  142 , et seq. may be used, including the configurations described herein, variations or combinations of such configurations, or other configurations. Any of the face members  140 , et seq. and the body members  142 , et seq. described herein can be used in combination, although some such combinations may require modification from the depicted structures. As another example, any of the various doping materials and configurations, connecting structures, materials, and forming methods described herein can be used with any other embodiment described herein, or variations thereof. In further embodiments, at least some of the features described herein can be used in connection with other configurations of iron-type clubs, wood-type clubs, other golf clubs, or other types of ball-striking devices. 
     Heads  102 , et seq. incorporating the features disclosed herein may be used as a ball striking device or a part thereof. For example, a golf club  100  as shown in  FIG. 1  may be manufactured by attaching a shaft or handle  104  to a head that is provided, such as the head  102  as described above. “Providing” the head, as used herein, refers broadly to making an article available or accessible for future actions to be performed on the article, and does not connote that the party providing the article has manufactured, produced, or supplied the article or that the party providing the article has ownership or control of the article. In other embodiments, different types of ball striking devices can be manufactured according to the principles described herein. In one embodiment, a set of golf clubs can be manufactured, where at least one of the clubs has a head according to one or more embodiments described herein. 
     A set of golf clubs  100  as described above may contain a series of heads  10 A-F ( FIGS. 15A-15F ), each having a ball striking face  12 A-F ( FIGS. 15A-15F ) with progressively increasing loft angles. In the embodiment illustrated, the set includes six golf club heads  10 A-F ( FIGS. 15A-15F ), with the faces  12 A-F ( FIGS. 15A-15F ) increasing in loft angle in sequence by approximately 5° increments, from about 20° to about 45°, such that the loft angle of each of the heads  10 A-F is about 5° greater than the previous head  10 A-F in the sequence. In other words, the heads  10 A ( FIG. 15A ),  10 B ( FIG. 15B ),  10 C ( FIG. 15C ),  10 D ( FIG. 15D ),  10 E ( FIG. 15E ), and  10 F ( FIG. 15F ) have faces  12 A-F ( FIG. 15A-15F ) that have loft angles of about 20°, 25°, 30°, 35°, 40°, and 45°, respectively. A typical set of golf clubs  100  has seven clubs  100  with loft angles increasing from about 19° to about 45°, and thus, has one additional golf club  100  compared to the set illustrated in  FIG. 15A-15F . By reducing the number of clubs  100  in the set, the cost of producing the entire set is reduced. Accordingly, if more expensive techniques and/or materials are used to produce a set of clubs, the set can be produced at a more competitive cost. This may be advantageous, as at least some embodiments described herein may incorporate more costly techniques and/or materials in production. It is understood that the set may have at least one additional club  100 , such as a pitching wedge, a sand wedge, a gap wedge, a lob wedge, and/or another longer or shorter iron club, and may also be provided with one or more clubs of a different type, such as a wood and/or a putter. 
     A set of golf clubs  100  as described above may also be configured with progressive weighting, such as the set of golf clubs shown in  FIG. 15A-15F . For example, at least one of the six heads  10 A-F may have the doped portion located in a different location relative to the doped portion of at least one other of the six heads  10 A-F ( FIGS. 15A-15F ). In another example, each of the six heads  10 A-F has the doped portion located in a different location relative to the doped portions of each of the other heads  10 A-F. In one embodiment, described with respect to a head  102  configured as shown in  FIGS. 2-4 , the weighting of the club head  102  may be adjusted so that the position of the center of gravity may be progressively moved from heel  120  toward the toe  122  as the club heads  102  progress from longer to shorter irons. Likewise, the position of the center of gravity of the head  102  can be adjusted upward or downward as desired. In one example, the center of gravity may be lower on longer irons, in order to better facilitate getting the ball airborne, and may be higher on shorter irons, in order to achieve greater control.  FIG. 16  schematically illustrates one embodiment of this progressive weighting, with respect to the set of club heads  10 A-F shown in  FIG. 15A-15F , illustrating the doped portion  144  being located lower and more toward the heel  120  in the longest iron head  10 A and moving higher and toward the toe  122  as the irons progress from long to short (i.e.,  10 A- 10 B- 10 C- 10 D- 10 E- 10 F). In another example embodiment, various body members  142 , et seq. with doped portions  144  as described above can be used to customize one or more golf clubs, or even a set of golf clubs, for a particular golfer, based on swing characteristics of the golfer for a particular club or clubs. For example, if a golfer has trouble closing the face while swinging a particular iron, more weight may be added to the heel  120 , et seq. of that club head  102 , et seq. As another example, the weighting of the head  102 , et seq. may be adjusted to compensate for a common hitting pattern, such as if a golfer frequently strikes the ball in a specific location on the face  112 , et seq. In further embodiments, still other types of progressive weighting can be utilized. 
     Additionally, as described above, the head  102 , et seq., golf club  100 , or other ball striking device may be fitted or customized for a person by custom fitting, which may include selecting a specific body member  142 , et seq., with desired weighting characteristics and connecting the body member  142 , et seq., to a selected face member  140 , et seq. Further, in one embodiment, the body member  142 , et seq., may be removable from the face member  140 , et seq. In this configuration, the head  102 , et seq., may be further customizable by removing one body member  142 , et seq., and interchanging it with another body member  142 , et seq., with a different shape, weighting configuration, or other characteristic. Various other different configurations are possible, and various other club heads may be designed for various performance characteristics. 
     Further, heads  102 , et seq., as shown and described herein may include the doping material and the doped portion(s)  144  in any position or configuration. For example, as described above, lateral portions (e.g. heel  120  and/or toe  122  portions) of the heads  102 , et seq., may include doped portions.  FIGS. 17-19  illustrate examples of such embodiments. As shown in  FIG. 17 , the head  502  includes doped portions  544 A that form the outer perimeter portions of the sole  518  and the lower portions of the heel  520  and toe  522 . This creates a weighting configuration that lowers the center of gravity and increases the moment of inertia of the club head  502 . The head  502  shown in  FIG. 18  includes a doped portion  544 B that forms the portions of the sole  518  located toward the toe  522 , as well as the lower portions of the toe  522 . This creates a weighting configuration that moves the center of gravity lower and toward the toe  522 . The head  502  shown in  FIG. 19  includes a doped portion  544 C that forms the portions of the sole  518  located toward the heel  520 , as well as the lower portions of the heel  520 . This creates a weighting configuration that moves the center of gravity lower and toward the heel  520 . In other embodiments, other configurations can be used to achieve different weighting configurations, and in further embodiments, similar configurations can be used with other club heads. As another example, the doped portion(s)  144  may form a larger proportion of the club head  102 , et seq., and in one embodiment, the majority of the body member  142 , et seq., may contain the doping material, and weighting characteristics may instead be controlled by adjusting the positions of the non-doped portions. 
     The ball striking devices and heads therefor as described herein provide many benefits and advantages over existing products. For example, the use of the doping material in specific locations on a club head can be used to control the weighting of the club head, including the weight, weight distribution, moment of inertia, etc. This permits club head designers to manipulate the weighting and weight distribution (including COG, MOI, etc.) within the framework of a typical club design, which can reduce or eliminate the need to use a radical geometry. As one example, a standard blade-type iron configuration can be manufactured with a number of different weighting configurations without significant changes in geometry. Additionally, weighted body members  142 , et seq., as described herein can be used with a set of golf clubs to create progressive weighting or customized weighting among the clubs of the set. Further, the reduction in the number of clubs in a set may permit more expensive techniques and/or materials to be used in production, while maintaining the ability to offer the set at a reasonable price. Still further benefits and advantages may be recognizable by those skilled in the art. 
     While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and methods. Thus, the spirit and scope of the invention should be construed broadly as set forth in the appended claims.