Patent Publication Number: US-2018036605-A1

Title: Set of golf club heads and method of manufacture

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation-In-Part of U.S. patent application Ser. No. 15/332,864, filed on Oct. 24, 2016, which is a Continuation-In-Part of U.S. patent application Ser. No. 15/188,726, filed on Jun. 21, 2016, which is a Continuation-In-Part of U.S. patent application Ser. No. 14/078,380, filed on Nov. 12, 2013, now U.S. Pat. No. 9,387,370, which is a Continuation-In-Part of U.S. patent application Ser. No. 13/927,764, filed on Jun. 26, 2013, which is a Continuation-In-Part of U.S. patent application Ser. No. 13/305,087, filed on Nov. 28, 2011, now U.S. Pat. No. 8,926,451, the disclosure of which are all incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a co-forged golf club head formed from two or more materials and the method of manufacture for such a golf club head. More specifically, the present invention relates to the creation of an iron type golf club head from a pre-form billet that already contains two or more materials before the actual forging process; resulting in a multi-material golf club head that doesn&#39;t require any post manufacturing operations such as machining, welding, swaging, gluing, and the like. 
     BACKGROUND OF THE INVENTION 
     Golf is hard! When your average golfer swings a golf club, he or she may have dramatic variations in his or her golf swing, resulting in numerous off-center hits, which result in diminished performance when compared to a direct center hit. However, in an attempt to make this very difficult game more enjoyable for the average golfer, golf club designers have came up with unique golf club designs that will mitigate the harsh realities of a less than perfect golf swing. 
     In one early example, U.S. Pat. No. 4,523,759 to Igarashi discloses a perimeter weighted hollow golfing iron having a foam core with an effective hitting area concentrated toward the center of moment in an attempt to help make the game of golf easier. Distributing the weight of a golf club to the perimeter allow the moment of inertia (MOI) of a golf club head to be increased, reducing the undesirable twisting a golf club as it impacts a golf ball. 
     U.S. Pat. No. 4,809,977 to Doran et al. shows another example of an attempt to increase the moment of inertia of a golf club head by placing additional weights at the heel and toe portion of the golf club head. This increase in the moment of inertia of the golf club head achievable by increased heel and toe weighting could further prevent the golf club from twisting in a heel and toe direction, which mitigates the undesirable effect of sending a golf ball off the intended trajectory. 
     Although the initial attempts at increasing the forgiveness and playability of a golf club for an average golfer are admirable, it does not take advantage of the extreme forgiveness that can be achievable by utilizing different materials to form different portions of the golf club head. In one example, U.S. Pat. No. 5,885,170 to Takeda shows the advantage of using multi-materials to create more extreme adjustment of the mass properties. More specifically, U.S. Pat. No. 5,885,170 teaches a body having a face formed of one material while a hosel is formed from another material having different specific gravity from that of the head body. U.S. Pat. No. 6,434,811 to Helmstetter et al. shows another example of utilization of multiple materials to improve the performance of a golf club head by providing a golf club head with a weighting system that is incorporated after the entirety of the golf club head has been formed. 
     More recently, the improvements in incorporating multi-materials into a golf club head has matured significantly by incorporating numerous multiple materials of different characteristics by machining cavities into the golf club head. More specifically, U.S. Pat. No. 7,938,739 to Cole et al. discloses a golf club head with a cavity integral with the golf club head, wherein the cavity extends from the heel region to the toe region; extending along a lower portion of the back face of the golf club head; extends approximately parallel to the strike face; and is approximately symmetrical about a centerline that bisects the golf club head between the heel region and the toe region. 
     However, as multiple materials are introduced into the golf club after the body has been completed, the tolerances of the interfaces between the different materials could potentially cause undesirable side effects of altering the feel of the golf club head. U.S. Pat. No. 6,095,931 to Hettinger et al. identifies this specific undesirable side effect of sacrifice in the feel by the usage of multiple different components. U.S. Pat. No. 6,095,931 addresses this issue by providing an isolation layer between the golf club head and the main body portion that comprises the striking front section. 
     U.S. Pat. No. 7,828,674 to Kubota recognizes the severity of this problem by stating that hollow golf club heads having viscoelastic element feels light and hollow to the better golfer, hence they do not prefer such a golf club. U.S. Pat. No. 7,828,674 address the deficiencies of such a multi-material golf club by incorporating a block of magnesium to be embedded and or press-fitted into the recess formed in the metal only to be sealed with a metallic cover. 
     Despite all of the above attempts to improve the performance of a golf club head all while trying to minimize the sacrifice in feel of a golf club, all of the methodologies require a significant amount of post manufacturing operation that creates cavities and recesses in the club head for the secondary material to be incorporated. These type of secondary operations are not only expensive, but the ability to maintain a tight enough tolerance between the various components make is very difficult to maintain the solid feel generally associated with an unitarily formed golf club head. 
     Hence, it can be seen from above, despite all the development in creating a golf club head that&#39;s more forgiving without sacrificing the feel associated with a conventional club head, the current art is incapable of creating such a club without utilizing severe post manufacturing machining that causes bad feel. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect of the present invention is a forged golf club head comprising a body portion having a striking surface made out of a first material, and at least one weight adjustment portion made out of a second material encased within the body portion; wherein the at least one weight adjustment portion is encased monolithically within the body portion of the golf club head without any secondary attachment operations. 
     In another aspect of the present invention is a method of forging a golf club head comprising of the steps of creating a cylindrical billet out of a first material, machining one or more cavities within the cylindrical billet, partially filling the one or more cavities with a second material to create a weight adjustment portion, filling the remaining volume of the one or more cavities with the first material to encase the weight adjustment portion, and forging the cylindrical billet to create a body portion of the golf club head; wherein the body portion monolithically encases the weight adjustment portion within a body of the golf club head without any secondary attachment operations. 
     In another aspect of the present invention is a forged golf club head comprising a body portion having a striking surface made out of first material, and at least one weight adjustment portion made out of a second material encased within the body portion; wherein the at least one weight adjustment portion is encased monolithically within the body portion without any secondary attachment operations. The first material has a first flow stress at a first forging temperature and the second material has a second flow stress at a second forging temperature, wherein the first flow stress and the second flow stress are substantially similar to one another, and the first forging temperature and the second forging temperature are substantially similar to one another and the first forging temperature and the second forging temperature are substantially similar to one another. The first material has a first thermal expansion coefficient and the second material has a second thermal expansion coefficient, wherein the first thermal expansion coefficient is greater than or equal to the second thermal expansion coefficient. 
     In yet another aspect of the present invention is a forged golf club head comprising of a body portion made out of a first material having a face cavity and at least one weight cavity, at least one high density weight adjustment portion made out of a second material encased within the weight cavity, a lightweight weight adjustment portion made out of a third material encased within the face cavity, and a striking face insert made out of the first material adapted to cover the face cavity; wherein the lightweight weight adjustment portion further comprises of a plurality of two or more cutouts, and wherein the high density weight adjustment portion is encased monolithically within the weight cavity. 
     In another aspect of the present invention, the pluralities of two or more cutouts are of a circular shape, and the circular shapes have a diameter of between about 1.0 mm to about 3.0 mm. 
     In another aspect of the present invention, the plurality of two or more cutouts may be at least partially filled with a polymer. 
     In yet another aspect of the present invention is a method of forging a golf club head comprising of first pre-forging a cylindrical billet to create a body portion of the golf club head wherein the body portion of the golf club head comprises of a face cavity and at least one weight cavity. Once the pre-forging is done, the at least one weight cavity is at least partially filled with a second material to create a high density weight adjustment portion and the face cavity is at least partially filled with a third material to create a lightweight weight adjustment portion. Then a cap is provided to at least partially encase the high density weight adjustment portion and a striking face insert is provided to cover the lightweight weight adjustment portion. Finally, the body portion containing the high density weight adjustment portion and the lightweight weight adjustment portion is post forged to create a golf club head wherein the post forging process deforms an internal surface of the striking face insert into the plurality of two or more cutouts. 
     In another aspect of the present invention, both said face cavity and the at least one weight cavity have an opening towards a frontal portion of the golf club head such that the striking face insert completely covers both the face cavity and the at least one weight cavity. 
     In another aspect of the present invention, the lightweight weight adjustment portion further comprises a plurality of two or more cutouts, and the plurality of two or more cutouts form a draft angel to create a countersink. 
     In another aspect of the present invention is a plurality of two or more golf club heads comprising, a first golf club head having a first loft, a first bounce angle, and a first CG height location from a leading edge of the first golf club head, a second golf club head having a second loft, a second bounce angle, and a second CG height location from a leading edge of the second golf club head, wherein if the first loft and the second loft are substantially the same, then the first CG height location from the leading edge and the second CG height location from the leading edge are the same. 
     In another aspect of the present invention the CG height is kept the same even if the first loft and the second loft are substantially different. 
     These and other features, aspects and advantages of the present invention will become better understood with references to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
         FIG. 1  of the accompanying drawings shows a perspective view of a co-forged golf club head in accordance with an exemplary embodiment of the present invention; 
         FIGS. 2A-2D  shows perspective views of pre-formed billets used to create a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIGS. 3A-3D  shows perspective views of pre-formed billets used to create a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIGS. 4A-4D  shows perspective views of pre-formed billets used to create a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIGS. 5A-5D  shows perspective views of pre-formed billets used to create a golf club head in accordance with an exemplary embodiment of the present invention 
         FIG. 6  shows an exploded rear perspective view of a golf club head created using a multi-step co-forging method in accordance with a further alternative embodiment of the present invention; 
         FIG. 7  shows an exploded frontal perspective view of a golf club head created using a multi-step co-forging method in accordance with a further alternative embodiment of the present invention; 
         FIG. 8  shows a pre-formed billet used in a multi-step co-forging method to create a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 9  shows a bent pre-formed billet during one of the multi-step co-forging process in accordance with an alternative embodiment of the present invention; 
         FIGS. 10 a  and 10 b    shows a rear and frontal view of a golf club head during one of the multi-step co-forging process in accordance with an alternative embodiment of the present invention; 
         FIGS. 11 a  and 11 b    shows a rear and frontal view of a golf club head during one of the multi-step co-forging process in accordance with an alternative embodiment of the present invention; 
         FIGS. 12 a  and 12 b    shows a rear and frontal exploded view of a golf club head during one of the multi-step co-forging process in accordance with an alternative embodiment of the present invention; 
         FIGS. 13 a  and 13 b    shows a rear and frontal view of a golf club head during one of the multi-step co-forging process in accordance with an alternative embodiment of the present invention; 
         FIGS. 14 a  and 14 b    shows a rear and frontal view of a finished golf club head after the multi-step co-forging in accordance with an alternative embodiment of the present invention; and 
         FIG. 15  shows a frontal view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 16  shows a frontal view of a golf club head in accordance with an alternative embodiment of the present invention without the striking face showing a cavity; 
         FIG. 17  shows a perspective exploded view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 18  show a back view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 19  shows a toe side exploded view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 20  shows a heel side exploded view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 21  shows an exploded perspective view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 22  shows another exploded perspective view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 23  shows a frontal view of a golf club head in accordance with an alternative embodiment of the present invention allowing cross-sectional line A-A′ to be shown; 
         FIG. 24  shows a cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 25  shows an enlarged cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 26  shows an exploded frontal perspective view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 27  shows an exploded rear view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 28  shows a cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 29  shows an enlarged cross-sectional view, as illustrated by circular region A, of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 30  shows an enlarged cross-sectional view, as illustrated by circular region A, of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 31  shows an enlarged cross-sectional view, as illustrated by circular region A, of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 32  shows an enlarged cross-sectional view, as illustrated by circular region A, of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 33  shows an enlarged cross-sectional view, as illustrated by circular region A, of a golf club head in accordance with an alternative embodiment of the present invention 
         FIG. 34  shows an enlarged cross-sectional view, as illustrated by circular region A, of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 35  shows a cross-sectional view of a golf club head in accordance with an even further alternative embodiment of the present invention; 
         FIG. 36  shows a cross-sectional view of a golf club head in accordance with an even further alternative embodiment of the present invention; 
         FIG. 37  shows a graphical representation of Center of Gravity (CG) locations of a set of golf club heads having different lofts and bounces in accordance with the present invention; and 
         FIG. 38  of shows a graphical representation of Center of Gravity (CG) locations of a set of golf club heads having different loft and bounces in accordance with an alternative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
     Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
       FIG. 1  of the accompanying drawings shows a perspective view of a golf club head  100  in accordance with an exemplary embodiment of the present invention. The golf club head  100  shown in  FIG. 1  may generally comprise of a body portion  102  and a hosel portion  104 , with the body portion  102  having several individually identifiable components such as a topline portion  106 , a sole portion  108 , a heel portion  110 , and a toe portion  112 . The golf club head  100  in accordance with an exemplary embodiment of the present invention may generally be comprised of at least one weight adjustment portion that is encased within the body portion  102  of the golf club head  100 . In a preferred embodiment, the weight adjustment portion may be monolithically encased within the body portion  102  to ensure that the weight adjustment portion is secured within the body portion  102  without departing form the scope and content of the present invention. Because the weight adjustment portion is monolithically encased within the body portion  102  of the golf club head  100 , these weights are not visible in  FIG. 1  of the accompanying drawings. However, these weight adjustment portions will be shown in more detail in later figures, when various different views are presented. 
     Before moving onto subsequent figures, it is worthwhile here to emphasize that the current golf club head  100  is created using a forging process and the weights are incorporated without any post finish machining operations. This is an important distinction to establish because the same result of a monolithically encasing a weight adjustment portion is extremely difficult to achieve using alternative manufacturing processes such as casting. “Monolithically encased”, as referred to in the current patent application, may generally be defined as a having a specific internal component placed inside a separate external component without joints or seams in the finished product. With respect to the current invention, having weight adjustment portions “monolithically encased” within the body portion  102  of the golf club head  100  may generally refer to the ability to have weight adjustment portions placed inside the body portion  102  of the golf club head without joints or seams that are generally required by post manufacturing processes such as milling, welding, brazing, gluing, or swaging. 
     It should also be noted here that a weight that is “monolithically encased” within the current definition of the present invention could potentially have certain aspect of the internal weights exposed in the finish product to illustrate the existence of a weight adjustment portion without departing from the scope and content of the present invention. More specifically, “monolithically encased” refers to the methodology used to create the ultimate product as described above, and may not necessarily be limited to visually concealing the weight adjustment member. 
       FIGS. 2A-2D  illustrate the methodology used to create a co-forged golf club head  200  in accordance with an exemplary embodiment of the current invention. More specifically,  FIGS. 2A-2D  illustrate the steps involved in the forging of a golf club head from its rudimentary billet  201  shape into the final product of a golf club head  200 . 
       FIG. 2A  shows a pre-formed billet  201  in accordance with an exemplary embodiment of the present invention. As it can be seen from  FIG. 2A , the pre-form billet  201  may generally begin as a cylindrical rod formed from a first material, as it is common with the forging of a golf club head  200 . In order to create a weight adjustment portion  215  that can be monolithically encased within the body portion  202  of the golf club head  200 , one or more cavities  216  are machined into the pre-form billet  201 . In this current exemplary embodiment shown in  FIG. 2A , two cavities  216  are machined into the terminal ends of the pre-form billet  201 . The location and geometry of the cavities  216  within the pre-form billet  201  are important, as it correlates directly with the ultimate location of the weight adjustment portion  215  in the golf club head  200  after forging. 
     Moving onto  FIG. 2B , it can be seen that once the cavities  216  are machined, the cavities  216  are partially filled with a second material that has a density different from the density of the first material in order to create the weight adjustment portion.  215 . Similar to the discussion above, the location, size, and shape of the weight adjustment portion  215  is just as critical as the location, size, and shape of the cavities  216 , as the weight adjustment portion  215  within the pre-form billet  201  correlates with the ultimate resting place of the weight adjustment portion  215  in the golf club head. 
     Finally,  FIG. 2C  shows the final phase of the pre-form billet  201  as the remaining volume of the cavities  216  are filled with the first material and sealed through traditional joining methods such as welding, brazing, and swaging. Sealing the cavities  216  allows the weight adjustment portion  215  to be monolithically encased within the body of the pre-form billet  201 , which will allow the same weight adjustment portion  215  to be monolithically encased in the body  202  of the golf club head  200  after the forging process. After the cavities  216  are filled, the pre-form billet  201  is subjected to the normal forging process associated with the forging of a golf club head  200 . Although the basic steps involved in forging a golf club head  200  are important to the understanding of the current invention, it involves a relatively archaic and established technique, which the present application will not dive into much detail. More information regarding the steps involved in the forging of a basic golf club head without monolithically encased weight adjustment portions can be found in U.S. Pat. No. 3,825,991 to Cornell, and U.S. Pat. No. 6,666,779 to Iwata et al., the disclosure of which are all incorporated by reference in its entirety. 
     Although the above discussion regarding the forging of a golf clubs incorporated by reference do a good job describing the actual forging process, it fails to address the additional concerns with the co-forging process of the current invention wherein two different materials are involved in this forging process. More specifically, because a weight adjustment portion  215  is made out of a second material that could be different from the first material used to create remainder of the pre-form billet  201 , special care must be taken to ensure that the different materials can be forged together to form a golf club head  200 . Hence, in order to select two cohesive materials that are capable of being co-forged together, the first material and the second material may generally have to have very specific material properties requirements with respect to their flow stress and their thermal expansion coefficient. Although it is most preferential for the two materials to have identical material properties yielding in consistency in forging, the usage of identical materials may not offer any weight adjustment benefits required for the basis of the current invention. 
     First of, in order for metallic materials to have the capabilities of being co-forged together, the respective flow stress&#39; of each of the materials needs to be properly considered. Flow stress of a material, may generally be defined as the instantaneous value of stress require for continued deforming the material (i.e. to keep the metal flowing); and the creation of a cohesive forged component from two different materials will require them to flow at relatively the same speed when subjected to the stresses of the forging process. It is commonly known that the flow stress of a material is generally a function of the yield strength, the flow stress of a material may generally be summed up by Eq. (1) below. 
       Y f =Ke n    Eq. (1)
 
     wherein 
     Y f =Flow Stress (MPa) 
     K=Strain Coefficient (MPa) 
     N=Strain Hardening Exponent 
     In addition to the above equation, it is worthwhile to mention here that the flow stress of a material may not be construed in vacuum, but rather, it is a function of the forging temperature of the material as well. Hence, in a current exemplary embodiment of the present invention, a first flow stress of the first material at its first forging temperate is substantially similar but not identical to the second flow stress of the second material at its second forging temperature; with the first forging temperature and the second forging temperature being substantially similar. More specifically, in a more detailed embodiment, the first material may be 1025 steel having a first flow stress of about 10 ksi (kilo-pound per square inch) at a forging temperature of about 1,200° C., while the second material may a Niobium material having a second flow stress of also about 12 ksi at a forging temperature of about 1,100° C. 
     Although in the exemplary embodiment of the present invention described above, the first material may be a 1025 steel and the second material may be a Niobium material, various other materials may also be used without departing from the scope and content of the present invention so long as their flow stresses are similar at a similar forging temperature. Alternatively speaking, any two materials may be used in the current co-forging process so long as the second flow stress is no more than 20% greater or no less than 20% lesser than the first flow stress. 
     As mentioned before, other than flow stress, the thermal expansion coefficient of the first and second materials are also important to the proper co-forging of two distinct materials. More specifically, a first thermal expansion coefficient of the first material may generally need to be greater than or at least equal to the second thermal expansion coefficient of the second material. Because the thermal expansion coefficient also relate to the shrinkage of the material after forging, it is important that the first material that monolithically encases the second material have a higher thermal expansion coefficient to prevent gaps from forming at the interface portion of the materials. In a more detailed embodiment of the present invention, the first material may be 1025 steel having a thermal expansion coefficient of about 8.0 μin/in° F., while the second material may be Niobium having a second thermal expansion coefficient of about 3.94 μin/in° F. 
     It should be noted that although in the above exemplary embodiment the second thermal expansion coefficient is smaller than the first thermal expansion coefficient, the numbers can be identical to achieve perfect mating of the two materials without departing from the scope and content of the present invention. In fact, in one exemplary embodiment of the present invention, it may be preferred for the first material and the second material to have the same thermal expansion coefficient, as excessive shrinkage of the outer material upon the inner material could potentially create additional stresses at the interface portions of the two materials. 
     Alternatively, in an attempt to provide different weighting characteristics, the second material could be made out of a 6-4 Titanium material to reduce the weight of the weight adjustment portion  215 . The Titanium material may generally have a flow stress of about 10 ksi at a forging temperature of about 1,100° C. and a thermal expansion coefficient of about 6.1 μin/in° F. 
     Now that the forging process, and the specific concerns involving the co-forging of different materials have been discussed,  FIG. 2D  of the accompanying drawings shows a perspective view of a finished golf club head  200  created using the co-forging process above, wherein the golf club head  200  monolithically encases at least one weight adjustment portion  215  within the body portion  202 . More specifically, in the current exemplary embodiment of the present invention, the weight adjustment portions  215  are placed near a heel portion  210  and a toe portion  212  of the golf club head  200 . The placement of the weight adjustment portion  215  near a heel portion  210  and the toe portion  212  allow the golf club head  200  to have an increase in the Moment of Inertia (MOI) without the need for any secondary attachment operations; which will result in a more consistent feel upon impact with a golf ball. 
     Before moving onto a discussion regarding different embodiments of the present invention, it is worthwhile here to note that the exact placement of the weight adjustment portion  215  within the body portion  202  of the golf club head  200  is slightly different in every single different club head, this is the outcome of the current inventive co-forging process involves different materials. More specifically, the exact placement of the weight adjustment portion  215  may differ with each single golf club  200 , as the flow stress of the first material and the second material will help determine the final location of the weight adjustment portion  215 . In addition to the above, it should be noted that the interface between the weight adjustment portion  215  and the body portion  202  of the golf club head  200  may generally be an irregular interface, with the boundaries jagged to indicate that the entire golf club head  200  has been co-forged. This is dramatically different from a cavity created via a post machining secondary operations such as milling and drilling; which generally have clean bifurcation lines of the two different materials. 
       FIGS. 3A-3D  of the accompanying drawings shows an alternative embodiment of the present invention wherein two separate weight adjustment portions  314  and  315  are placed at different portions of the pre-form billet  301  to create a golf club head  300  with a different performance criteria. More specifically, the golf club head  300  shown in  FIG. 3D  may have a lightweight weight adjustment portion  314  near a topline portion  306  of the golf club head  300  and a heavyweight weight adjustment portion  315  near a sole  308  of the golf club head  300  to help shift the Center of Gravity (CG) of the golf club head  300  lower to help with launch and spin characteristics of the current inventive golf club head  300 . 
       FIG. 3A-3C , similar to before, show the formation process of the current inventive golf club head  300 , starting from a pre-form billet  301 . More specifically,  FIG. 3A  shows a perspective view of a pre-form billet  301  in accordance with an exemplary embodiment of the present invention wherein a plurality of cavities  316  are drilled at strategic locations within the billet  301 . It should be noted that in this current exemplary embodiment the plurality of cavities  316  are drilled near a top portion and a bottom portion of the pre-form billet  301  instead of at each of the terminal ends, as this specific embodiment focuses on lowering the CG of the golf club head  300  by removing weight from the top line portion  306  of the golf club head  300  and shifting it towards a sole portion  308  of the golf club head  300 . 
       FIG. 3B  of the accompanying drawings shows two weight adjustment portions  314  and  315  being placed inside the cavities  316  created in  FIG. 3A . Although it may generally be desirable to minimize the weight near a top portion of a golf club head  300  when one desires to lower the CG, top cavity  316  can not be left completely blank in this current embodiment of the present invention, as the entire pre-form billet  301  will eventually be forged into the shape of a golf club head  300 , causing any empty cavity  316  to collapse upon itself. Hence, in this current exemplary embodiment of the present invention, the top cavity  316  may be filled with a lightweight weight adjustment portion  314 , while the lower cavity  316  may be filled with a heavyweight weight adjustment portion  315 . The lightweight weight adjustment portion  314  may generally be made out of a third material having a third density, wherein the heavyweight weight adjustment portion  315  may generally be made out of second material having a second density. In one exemplary embodiment of the present invention, the third density may generally be less than about 7.0 g/cc, wherein the second density may generally be greater than about 7.8 g/cc; while the first material used to form the body portion  302  of the golf club head  300  may generally have a first density of about 7.8 g/cc. 
       FIG. 3C  of the accompanying drawings shows the final stage of the pre-form billet  301  that has monolithically encased the weight adjustment portions  314  and  315  within the internal cavities  316  of the pre-form billet  301 . More specifically, the creation of the pre-form billet shown in  FIG. 3C  involves filling in the remaining volume of the cavities  316  with a first material to encase the weight adjustment portions  315  and  316  within the pre-form billet  301 . Similar to the above discussion, the pre-form billet  301 , is subsequently forged to create a golf club head  300  as shown in  FIG. 3D , wherein the weight adjustment portions  314  and  315  are monolithically encased within the body portion  302  of the golf club head  300 . 
     Similar to the methodology described above, the co-forging of the third material within the cavity created within the first material, the third material may generally need to have a third flow stress that is similar with the first flow stress of the first material and a third thermal expansion coefficient less than the first thermal expansion coefficient of the first material. More specifically, in one exemplary embodiment of the present invention, the third material may be a 6-4 Titanium material having a third flow stress of about 10 ksi at a forging temperature of about 1,100° C. and a third thermal expansion coefficient of about 6.1 μin/in° F. 
     Although  FIGS. 2A-2D  and  FIGS. 3A-3D  show different embodiments of the present invention used to achieve a higher MOI and a lower CG respectively, these features are not mutually exclusive from one another. In fact, in a further alternative embodiment of the present invention shown in  FIGS. 4A-4D , features may be taken from both embodiments discussed above to create a co-forged golf club head with a higher MOI as well as a lower CG all without departing from the scope and content of the present invention. More specifically, in  FIGS. 4A-4D , the steps needed to incorporate a lightweight weight adjustment portion  414  near a top portion  406  of a golf club  400  together with two or more heavyweight weight adjustment portions  415  near a toe portion  412  and a heel portion  410  of the golf club head  400  to create a golf club with higher MOI and a lower CG. 
       FIG. 5A-5D  of the accompanying drawings shows a further alternative embodiment of the present invention wherein the body portion  502  of the golf club head  500  may be comprised of a monolithically encased weight adjustment portion  514 . In this current exemplary embodiment of the present invention, the weight adjustment portion  514  may be relatively large in size, allowing it to replace a majority of the body portion  502  of the golf club head  500  once the forging process is completely. In this current exemplary embodiment of the present invention, the monolithically encased weight adjustment portion  514  may generally be made out of a third material having a third density that is significantly lower than the first density of the first material used to form the body portion  502  of the golf club head  500 ; allowing weight to be taken out from the body portion  502  of the golf club head  500 . Because the lightweight third material used to form the weight adjustment portion  514  may generally be relatively soft compare to the first material, it is generally desirable to monolithically encase the weight adjustment portion  514  within the internal body of the golf club head  500 , allowing significant weight savings to be achieved without sacrificing feel. 
     More specifically  FIG. 5A  of the accompanying drawings shows a pre-form billet  501  similar to the previous figures. However, in this current exemplary embodiment, the cavity  506  is significantly larger within the pre-form billet  501  itself. This large cavity  506  can then be used in  FIG. 5B  to be filled with a weight adjustment portion  514  to adjust the weight, density, and overall feel of the golf club head  500 . In  FIG. 5C , similar to described above, the remaining volume of the cavity  516  is filled with the original first material before the entire pre-form billet  501  is subjected to the forging process to create a golf club head  500 . 
     It is worth noting here that in this current exemplary embodiment, the hosel portion  504  of the golf club head  500  is deliberately made from the conventional first material, as the bending characteristics of the second material used to form the weight adjustment portion  514  may generally not be suitable for the bending requirements of an iron type golf club head  500 . More specifically, the third material used to form the weight adjustment portion  514  could be a lightweight iron-aluminum material having a density of less than about 7.10 g/cc, more preferably less than about 7.05 g/cc, and most preferably less than about 7.00 g/cc, all without departing from the scope and content of the present invention. However, numerous other materials can also be used as the third material used to form the weight adjustment portion  514  without departing from the scope and content of the present invention so long as the third material has a density within the range described above. 
       FIG. 6  of the accompanying drawings shows an exploded rear perspective view of a golf club head  600  in accordance with a further alternative embodiment of the present invention utilizing a multi-step co-forging process. This multi-step co-forging process, the details of which will be described subsequently in  FIGS. 8-14 , allows for an improvement in the ability to precisely place different weight members within different parts of the golf club head  600 . This improvement in the ability to precisely place weighting members not only opens the door to allow multiple different materials to be forged together that were previously impossible due to their inherent material limitations, but it also allows for more improvements in the performance characteristics of a golf club  600  than previously discussed. 
     More specifically,  FIG. 6  of the accompanying drawings shows a co-forged golf club head  600  created using the multi-step co-forging process. The golf club head  600  have heavier density weight adjustment portions  615  at the heel  610  and toe  612  portion of the golf club head  600  corresponding to their respective cavities  616 . The weight adjustment portions  615  are then combined with caps  617  to retain the weight adjustment portions  615  together with the body of the golf club head  600  during the co-forging process. It should be noted that the current exemplary golf club head  600  utilizes a multi-step co-forging process to install the heavy weight adjustment portions  615  without the need of post manufacturing finishes such as welding, brazing, swaged, or the like. As previously mentioned, the benefit of utilizing such a co-forged process is the uniformity and consistency of the material, resulting in superior performance and feel. However, in addition to the benefit articulated above, the current embodiment of the present invention allows the heavy weight adjustment portions  615  to be placed at the extremities of the golf club head  600 , further improving the center of gravity location as well as the moment of inertia of the golf club head  600 . 
       FIG. 7  of the accompanying drawings shows an exploded frontal perspective view of a golf club head  700  in accordance with a further alternative embodiment of the present invention. More specifically, golf club head  700  incorporates a lightweight weight adjustment portion  714  behind a striking face  718  portion of the golf club head  700  within a cavity  716  in a multi-step co-forging process. In this current exemplary embodiment of the present invention, due to the precision co-forging process discussed above, the location and placement of the lightweight weight adjustment portion  714  can be more precisely placed, hence creating the opportunity to reduce weight from the striking face  718  portion of the golf club head  700 . In order to understand the current multi-step co-forging process,  FIGS. 8-14  have been presented below, detailing the steps involved in this multi-step co-forging process. 
       FIG. 8  of the accompanying drawings, similar to  FIGS. 2-5  above, show a pre-form billet  801  used to create a forged golf club head. This forged billet  801 , is then bent to an L-shape as shown in  FIG. 9  to prepare the billet  901  for the die that begins the forging process.  FIGS. 10 a  and 10 b    shows the frontal and rear view of a golf club head  1000  that&#39;s been subjected to the first step of the multi-step co-forging process. In this preliminary step, the billet has been forged to a shape that roughly resembles that of a golf club head  1000 . In fact, even in this early stage, the shape of the golf club  1000  can be seen, as it already has a hosel portion  1004 , a heel portion  1010 , and a toe portion  1012 . In the rear view of the golf club head  1000  shown in  FIG. 10 a   , preliminary imprints of the cavity  1016  can already be seen in the heel  1010  and toe  1012  portion of the golf club head; while in the frontal view of the golf club head  1000  shown in  FIG. 10 b   , the cavity  1016  can already be seen near the striking face. 
     Subsequent to the initial forging step, the excess trim  1030  may be removed from the golf club head  1000  and subsequent to that, subjected to another rough forging step. During the forging process, the excess material may flow outside of the confines of the die, resulting in what is commonly known as “flash”. This flash material, as previously discussed, may be trimmed off in between the individual multi-forging steps to improve the adherence to the die in subsequent steps. 
     The results of this secondary forging step can be shown in  FIGS. 11 a  and 11 b   . As it can be seen from  FIGS. 11 a    and  11   b,  the golf club head  1100  in this current state, is starting to take on a shape that more closely resembles that of a finished product. In addition to the overall shape being more defined, the boundaries and shapes of the cavities  1116  are also starting to take on their respective shape as well. Subsequent to this secondary forging step, the weight adjustment portions can be added into the specific cavities  1116  before the golf club head  1100  is subjected to the final forging step. 
     The relationship between the weight adjustment portions to the cavities  1116  on the golf club head  1100  can be shown more clearly in  FIGS. 12 a  and 12 b   . Here, in  FIGS. 12 a  and 12 b   , it can be seen that the cavity  1216  on the rear portion of the golf club head  1200  may be filled with weight adjustment portions  1215  that may generally have a higher density than the body of the golf club head  1200 . The high density weight adjustment portions  1215  may then be covered up with a cap  1217  made out of a similar material as the body of the golf club head  1200 , allowing high density weight adjustment portions  1215  to be retained within the cavity  1216 . In the front of the golf club head  1200 , the cavity  1216  may be filled with a weight adjustment member  1214  having a lower density than the body portion of the golf club head  1200 . Similar to the rear, this weight adjustment portion  1214  may be secured in the cavity  1216  with a cap like mechanism that also serves as a striking face  1218 . The striking face  1218 , similar to the cap  1217 , may be made out of a similar material as the body of the golf club head  1200 . Having the cap  1217  and the striking face  1218  be made out of the same material as the remainder of the body of the golf club head  1200  is beneficial because it allows these two components to be welded to the body portion of the golf club head  1200 . Having these components welded in place allows the weight adjustment portions  1215  to be secured within their own respective cavities  1216  before the final forging step that completes the current multi-step co-forging process. 
     In an alternative embodiment of the present invention, the cap  1217  may not even be necessarily needed to completely cover up the cavity  1216  and the weight adjustment member  1214 . In fact, in an alternative embodiment of the present invention, the cap  1217  only needs to partially cover the weight adjustment portion  1215  to a degree that sufficiently prevents the weight adjustment portion  1215  from separating from the body of the golf club head  1200 . 
     The final forging process involved in this process is generally creates a golf club head  1200  that can be considered “co-forged”, as now the golf club head  1200  contains two or more different materials being forged together in this final step.  FIGS. 13 a  and 13 b    show the results of the golf club head  1300  after it has completed the final co-forging step. In its current state, the golf club head  1300  has taken its final shape, and the weight adjustment members  1316  and  1314  are all now monolithically enclosed within their respective cavities by the caps  1317  and striking face plate  1318 . Although the golf club head  1300  may have taken their form, there are still excessive flash  1330  around the perimeter of the golf club head  1300  that needs to be trimmed before the golf club head  1300  takes its final form. 
       FIGS. 14 a  and 14 b    show the completed golf club head  1400  as a result of this co-forging process. As it can be seen here in  FIGS. 14 a  and 14 b   , the excess flash  1330  has already been trimmed, improving the aesthetic appeal of the golf club head  1400 . As previously mentioned, as a result of this co-forging process, the weight adjustment portions  1416  and  1418  are seamlessly and monolithically encased with the body of the golf club head  1400  via the cap  1417  and the striking face plate  1318 . As previously discussed, the advantage of having the weight adjustment portions  1416  seamlessly and monolithically encased with the body of the golf club head  1400  via this co-forged process is that it prevents rattling, and improves the solid feel of the golf club head  1400 . In fact, utilizing this process, the present golf club head can achieve a feel that is almost non-discernible from a unitary forged golf club head utilizing conventional forging methodologies. 
     Alternatively speaking, it can also be said that this present multi-step co-forging methodology creates a unique relationship between the weight adjustment portions  1416  and  1418  and the cavity  1216  (see  FIG. 12 ) that it sits in. More specifically, it can be said that the outer surface area of the weight adjustment portion  1416  may generally be identical to the inner surface area of the cavity  1216 . The cavity  1216  may generally include the surface area of any caps  1217  or face plate  1218  used to complete the cavity  1216  created by the rough forging steps. (See  FIG. 12 ) Although the symmetry in shape and surface area between the cavity  1216  and the weight adjustment portion  1416  may not appear like an innovative achievement initially, the reality of the situation is that unless a co-forged step is involved, such a seamless interface between the two components are impossible to achieve. Given the bonding constraints of the materials used for different parts of the golf club head, the current innovative co-forging method is the only way to achieve such a seamless interface between these components. 
       FIG. 15  of the accompanying drawings shows a frontal view of a finished product golf club head  1500  in accordance with an alternative embodiment of the present invention utilizing the co-forged technology previously described. In this embodiment, the striking face insert  1518  may only partially cover the lower portion of the golf club head  1500 , allowing a cavity to be created only in the lower portion of the golf club head  1500 . This specific bifurcation of the club head  1500  may be beneficial in improving the performance of the golf club head  1500  in creating a dual cavity design that provides structural support near the central hemisphere of the club head  1500  to provide a more solid feel during impact. 
       FIG. 16  of the accompanying drawings shows a frontal view of a golf club head  1600  without the striking face insert  1518  (shown in  FIG. 15 ). This view of the golf club head  1600  allows the internal face cavity  1616  to be shown more clearly, illustrating a plurality of support rods  1630  that may be used to further provide structural support to the striking face portion. In one embodiment, the plurality of rods  1630  may be circular rods as shown in  FIG. 16  dispersed throughout the internal walls of the face cavity  1616 . However, in other embodiments, the plurality of rods  1630  may not even be cylindrical, but be square, rectangular, or any other shape all without departing from the scope and content of the present invention so long as it is provides any sort of localized support for the striking face. In addition to the variation in the geometry of the rods  1630 , the placement of the rods  1630  need not be dispersed throughout the internal walls of the face cavity  1616 , in fact, the location of the rods  1630  may be placed at any one of many numerous locations all without departing from the scope and content of the present invention. Finally, it should be noted that in an alternative embodiment of the present invention, the face cavity  1616  may not even require any supporting rods  1630 , and the face cavity  1616  may be entirely hollow without departing from the scope and content of the present invention. 
       FIG. 17  of the accompanying drawings shows an exploded perspective view of a golf club head in accordance with the embodiment of the present invention shown in  FIGS. 15 and 16 . More specifically, this exploded view allows the relationship and fit between the striking face insert  1718  and the face cavity  1716  of the golf club head  1700  to be shown more clearly. It should be noted that although the earlier discussion talk about using a co-forged process to join together different metals that cannot be easily welded together, the connection between the striking face insert  1718  and the body of the golf club head  1700  involves a hollow face cavity  1716  portion that could cause the striking face insert  1718  to deform during a forging process. Luckily, in the current embodiment, the material used for the striking face insert  1718  may be similar to that of the body portion  1700 , allowing the two components to be joined together using a conventional welding process after the other components are co-forged together. 
     Another feature worth identifying is the length of the plurality of rods  1730 . The plurality of rods  1730 , in order to provide structural support to the striking face insert  1718 , may generally touch the rear surface of the striking face insert  1718 . Alternatively speaking, it can be said that the terminal ends of the plurality of rods  1716  may contact a rear surface of the striking face insert  1718  to provide the structural enhancement. However, in an alternative embodiment, the terminal ends of the plurality of rods  1716  may terminate just short of the rear surface of the striking face insert  1718  creating a gap; promoting face flexure upon impact with a golf ball while creating a backstop to preserve the elastic deformation of the striking face insert  1718  material. 
       FIG. 18  of the accompanying drawings shows a back view of a golf club head  1800  having one or more weights  1815  and caps  1817  joined together using the co-forged process described above. Without repeating the process described above,  FIGS. 19-20  will show a toe and heel exploded view of the various components that will be created using the co-forged process described above. 
       FIG. 19  shows an exploded toe perspective view of a golf club head  1900  illustrating the various components of the weighting system in accordance with this embodiment of the present invention. The exploded view of the golf club head  1900  is not illustrative of the methodology used to create the weighting system, but rather is only presented here to illustrate how the components could be used together in the co-forging process described above to create the golf club head  1900 . More specifically, the weighting system here comprises a weight cavity  1916 , a weight  1915 , a cap  1979 , and welding material  1920 . The weight cavity  1916  is formed here in the rough forging step, after which the weight  1915  is tack welded within the weight cavity  1916  with the cap  1917  using the welding material  1920 . After the various components are roughly connected to one another, the entire golf club head  1900  is subjected to a final forging step as described above in  FIGS. 13 a    and  13   b.    
       FIG. 20  shows an exploded heel perspective view of a golf club head  2000  illustrating the various components of the weighting system in accordance with this embodiment of the present invention. Similar to the discussion above for  FIG. 19 , this view is provided to illustrate the relationship between the components. 
     In addition to above, the current multi-step co-forging process may differ from the pure co-forging process in that it no longer requires the two materials to have similar flow stresses between the different materials. This elimination of the requirement that the material needs to have similar flow stresses may be beneficial because it allows a wider range of materials to be used, especially when it comes to exotic materials providing extreme weighting benefits such as Tungsten. The current multi-step co-forging process is capable of achieving this by forging the cavity for the weight before using a final cap type material to fill the gap around the cavity to completely enclose the weight adjustment portion within the cap type material. Despite the elimination of the need for the materials to have similar flow stress, the need for the second material to have a smaller thermal expansion coefficient as the first material still stands true in this multi-step co-forging process. This requirement still stands because the second material, although encompassed in a cavity via a cap, is still subjected to the same forging temperature as the external first material. Any excessive expansion of the second material would degrade the structural rigidity of the cap, causing potential failures in the bonding process. 
       FIG. 21  of the accompanying drawings shows an exploded view of a golf club head  2100  in accordance with an alternative embodiment of the present invention. In this alternative embodiment of the present invention, the golf club head  2100  may contain very similar components as previously mentioned, such as a plurality of high density weight adjustment portions  2115 , a plurality of caps  2117 , a lightweight weight adjustment portion  2114 , and striking face  2218  similar to the discussion earlier regarding  FIGS. 6 and 7 . However, it be seen here that the lightweight weight adjustment portion  2214  here looks significantly different from prior art embodiments in that it now incorporates a unique geometry not previously shown. More specifically, a closer examination of  FIG. 21  shows the lightweight weight adjustment portion further comprising a plurality of cutouts  2140  across the lightweight weight adjustment portion  2114 . It is worth noting here that the plurality of cutouts  2140  shown in this current exemplary embodiment may be substantially evenly distributed across the entirety of the lightweight weight adjustment portion  2114  to promote an even bond between the various components without departing from the scope and content of the present invention. The incorporation of this cutout  2140  feature into the lightweight weight adjustment portion serves to improve the performance of the golf club head in multiple aspects. In one aspect, the most immediate and recognizable benefit of the incorporation of the plurality of cutouts  2140  is the further reduction of weight in the lightweight weight adjustment portion  2114 . In addition to the benefit of removing weight from the lightweight weight adjustment portion  2114 , the plurality of cutouts  2140  may serve a subtle, but very important purpose of helping the lightweight weight adjustment portion from shifting its position relative to the body of the golf club head  2100  and the striking face  2128 . 
     Understanding that the current golf club head  2100  is created using the co-forging process described above, the ability of the various components to be formed together in a solidary structure is very important to the proper functionality of the overall club head  2100 . This structural integrity becomes even more important when an insert is added near the striking face portion  2128  of the golf club head  2100 . In order to help preserve the structural integrity of the various components, the plurality of cutouts  2140  allows a little bit of the material of the striking face  2128  to flow into the cutouts  2140 , creating a better bond between the different components. This deformation of the material of the striking face  2128  helps improve the bond between the components by prohibiting the materials from shifting relative to one another via a mechanical interface, increasing structural integrity. Finally, because the body portion is made out of a similar material as the striking face portion  2128 , this deformation effect exhibited by the striking face portion  2128  may occur at the rear surface of the lightweight weight adjustment portion  2114  together with the body of the golf club head  2100  without departing from the scope and content of the present invention. 
     In earlier embodiments of the present invention shown in  FIGS. 6 and 7 , a titanium lightweight face insert  714  would have a total weight of about 21 grams; however, in the current exemplary embodiment of the present invention shown in  FIG. 21 , the total weight of the lightweight weight adjustment portion  2114  could be reduced by greater than about 13%, more preferably greater than about 15%, and most preferably greater than about 17% all without departing from the scope and content of the present invention. In the same example above wherein a titanium material having a density of about 4.5 g/cm 3  is used, the mass of the lightweight weight adjustment could be less than about 18.5 grams, more preferably less than about 17.5 grams, and most preferably less than about 17 grams, all without departing from the scope and content of the present invention. 
       FIG. 22  of the accompanying drawings shows a reversed exploded view of a golf club head  2200  in accordance with an alternative embodiment of the present invention similar to the discussion in  FIG. 21 . In this reversed exploded view, the cavity  2216  to which the lightweight weight adjustment member  2214  is situated can be shown more clearly. It is worth noting here that the cutouts  2240  in this exemplary embodiment of the present invention may generally have a circular shape, having a diameter of between about 1.0 mm and about 3.0 mm, more preferably between about 1.50 mm and about 2.5 mm, and most preferably about 2.0 mm. The exact diameter of the cutouts  2240  is critical to the proper function of the lightweight weight adjustment member  2214  because not only does it need to provide a sufficient amount of weight reduction, it needs to properly balance the amount of sandwiching material from seeping into the cutouts  2240 . Although the preferred embodiment of the present invention utilizes circular shapes to create the cutouts  2240 , numerous other shapes such as oval, triangular, rectangular, or any other shapes capable of removing material from said lightweight weight adjustment member  2214  all without departing from the scope and content of the present invention. Another different way to quantify the importance of finding the right balance of the cutout  2240  dimension is as a function of the amount of surface area removed. In the current exemplary embodiment of the present invention, the amount of frontal surface area removed by the cutouts  2240  may generally be greater than about 15% of the total surface area and less than about 30% of the total surface area, more preferably greater than about 17.5% of the total surface area and less than about 27.5% of the total surface area, and most preferably greater than about 20% of the total surface area and less than about 25% of the total surface area. Given a striking face area of about 2,400 mm 2  in the current exemplary embodiment of the present invention, it can be said that the frontal surface area created by the cutouts  2240  in the lightweight weight adjustment member  2214  may generally be between about 360 mm 2  and less than about 720 mm 2 , more preferably greater than about 420 mm 2  and less than about 660 mm 2 , and most preferably greater than 480 mm 2  and less than about 600 mm 2 . 
     In order to illustrate the sandwiching material of the striking face  2218  and the body portion of the golf club head  2200  into the cutouts  2240 , a cross sectional view of the golf cub head  2200  needs to be provided. However, before a cross-sectional view can be shown,  FIG. 23  shows a frontal view of a golf club head  2300  allowing the cross-sectional line A-A′ to be shown. Cross-sectional line A-A′, as shown in this current exemplary embodiment may generally be taken across a central point of a striking face region of said golf club head  2300 . 
       FIG. 24  shows a cross-sectional view of a golf club head  2400  in accordance with an exemplary embodiment of the present invention taken along cross-sectional line A-A′ shown in  FIG. 23 . In this cross-sectional view of the golf club head  2400  it can be seen that the cutouts  2440  are spread out along the lightweight weight adjustment portion  2414  and is sandwiched between the striking face  2418  and the back portion of the golf club head  2400 . Although  FIG. 24  provides a very important view allowing the relationship between the various components to be shown more clearly, it is not zoomed in enough to illustrate the subtle flow of material during the final co-forging process described above that helps provide structural rigidity to the overall golf club head  2400 . In order to illustrate this, an enlarged cross-sectional view of the golf club head is provided in  FIG. 25 . 
       FIG. 25  of the accompanying drawings shows an enlarged cross-sectional view of a golf club head  2500  in accordance with an exemplary embodiment of the present invention. In this enlarged cross-sectional view of the golf club head  2500 , it can be seen that after the final forging step, a little bit of the material of the striking face  2518  has visibly sunk into the cutouts  2540 . It should be noted that the very critical dimension of the cutouts  2540  indicated above allows for this slight deformation in the back of the striking face  2518  without deforming the frontal surface of the striking face  2518 . In addition to the deformation of the striking face  2518 ,  FIG. 25  of the accompanying drawings also shows a deformation of the body portion of the golf club head  2500  at the rear of the cavity  2516 . It should be noted here that in this current exemplary embodiment of the present invention, the deformation of the striking face  2518  is greater than the deformation of the body portion of the golf club head  2500  at the rear of the cavity  2516  to ensure more structural rigidity. In addition to the front and back difference in the deformation, the striking face  2518  and the body portion of the golf club head  2500  may also have a top to bottom deformation difference. More specifically, a golf club head  2500  in accordance with an alternative embodiment of the present invention may generally have more deformation into the cutouts  2540  at the top near the topline than compared to the bottom near the sole. 
     In an alternative embodiment of the present invention, the plurality of cutouts  2540  may be completely filled or partially filled or impregnated with a polymer type material. Filling the cutouts  2540  with a polymer type material could improve the structural rigidity of the lightweight weight adjustment member  2514  and improve the feel of the golf club head  2500  during impact with a golf ball by providing vibration damping. The polymer filler could completely fill the cutouts  2540  or partially fill the cutouts  2540  both without departing from the scope and content of the present invention. In this alternative embodiment of the present invention wherein the cutouts  2540  are completely filled with the polymer, it is important to control the hardness of the polymer, as the hardness could impair the ability of the striking face  2518  and the body portion to create a mechanical lock. In one exemplary embodiment of the present invention the polymer filler within the cutouts  2540  may have a shore 00 hardness of 20 and up to a shore D hardness of 60. 
       FIG. 26  of the accompanying drawing shows an exploded perspective view of a golf club head  2600  in accordance with an alternative embodiment of the present invention. In this alternative embodiment of the present invention, the co-forged golf club head  2600  is similar to prior golf club heads that have multiple cavities; however all of the cavities  2616  in this embodiment are generally open towards the frontal portion of the golf club head  2600 . This arrangement of the cavities  2616  being opened towards the frontal portion of the golf club head  2600  allows the entirety of the cavities  2616  and their respective insert to be covered using one unitary cover, which in this instance is the striking face  2618 . Having the entirety of the cavities  2616  and their respective weight portion inserts being secured by one cover may be preferred as it dramatically simplifies the simplicity of the construction. In addition to the above, it is worthwhile to note here that the welding line between the striking face  2618  and the chassis of the golf club head  2600  occurs around a perimeter of the striking face  2618 . This placement of the separation is strategic, as it helps move the welding lines away from the high stress impact location on the striking face  2618 . 
     Focusing on the cavities  2616  shown in  FIG. 6 , it can be seen that the cavities  2616  may take on different geometric shapes and could be located at different locations within the golf club head  2600  depending on the desired center of gravity location. In this embodiment shown in  FIG. 6 , the golf club head may have a large cavity  2616  located near the upper portion of the golf club head  2600  adapted to engage a lightweight weight adjustment portion  2614 , a lower toe portion cavity  2616  adapted to engage a toe biased heavy density weight adjustment portion  2615 , and a lower heel portion cavity  2616  adapted to engage a heel biased heavy density weight adjustment portion  2615 . This embodiment allows removal of weight from the upper portion of the golf club head  2600  and addition of weight towards the bottom heel and toe portion of the golf club head  2600  to lower the center of gravity and increase the moment of inertia. Finally.  FIG. 26  also shows a plurality of cutouts  2640  being strategically located across the lightweight weight adjustment portion  2614  to help provide structural rigidity of all the components by allowing the material of the striking face  2618  and the chassis to seep into the cutouts  2640  as shown earlier in  FIG. 25 . 
       FIG. 27  shows rear exploded perspective view of a golf club head  2700  in accordance with a further alternative embodiment of the present invention. The golf club head  2700  shown in  FIG. 27  may be very similar to the golf club head  2600  shown in  FIG. 6 , but be further comprised out of a plurality of posts  2742  located at the rear surface of the striking face  2718 . The plurality of posts  2742  in this embodiment of the present invention is intended to engage the plurality of cutouts  2740  located on the lightweight weight adjustment portion  2714  to further prevent the movement of these components relative to another. These plurality of posts  2742 , combined with the plurality of cutouts  2740 , serve to create one homogenous part once it undergoes a secondary forging step that co-forges these components together similar to the method described by  FIGS. 10 through 13 . 
     In the current exemplary embodiment of the present invention, the plurality of posts  2742  are all located on the striking face  2718  for the ease of illustration. In alternative embodiments, the plurality of posts  2742  may be located on the other side of the lightweight weight adjustment portion  2614  within the upper cavity  2616  (see  FIG. 26 ) without departing from the scope and content of the present invention. In a further alternative embodiment of the present invention, the plurality of posts  2742  may be partially located on the rear surface of the striking face  2718  and partially located on the frontal surface of the upper cavity  2616  (see  FIG. 26 ) also without departing from the scope and content of the present invention. 
       FIGS. 28-34  of the accompanying drawings all provide cross-sectional views of the golf club head containing this plurality of posts  2742  and their respective plurality of cutouts  2740  in accordance with various different embodiments of the present invention. Before diving into the cross-sectional view of golf club head  2800  shown in  FIG. 28 , it is worth noting that the cross-sectional view is taken along cross-sectional line A-A′ shown in  FIG. 23  down the center of the club head  2800 . However, in different embodiments of the present invention, various other cross-sectional lines could be used without departing from the scope and content of the present invention so long as it contains the relationship between the plurality of posts  2842  and the plurality of cutouts  2840  illustrated. 
       FIG. 28  shows a cross-sectional view of a golf club head  2800  in accordance with an exemplary embodiment of the present invention wherein the plurality of posts  2842  are located on the rear surface of the striking face  2818 , while the plurality of cutouts  2840  are located in the lightweight weight adjustment portion  2814  that is sandwiched by the other components. The plurality of posts  2842  in this exemplary embodiment may all be of the same size to ensure consistent bond between the different posts during the final forging step; however, in alternative embodiments the plurality of posts can have varying diameters depending on the quality of the bond joint required without departing from the scope and content of the present invention. In order to provide a clearer illustration of the relationship between the plurality of posts  2842  and the plurality of cutouts  2840 , an enlarged cross-sectional view of the golf club head  2800  focusing on circular region A is shown in  FIG. 29 . 
       FIG. 29  of the accompanying drawings shows an enlarged cross-sectional view of circular region A shown in  FIG. 28 . In addition to providing a clearer illustration of the relationship between the plurality of posts  2942  on the rear surface of the striking face  2918  and the plurality of cutouts  2940 ,  FIG. 29  allows the diameter d 1  of the plurality of posts to be illustrated more clearly. The diameter d 1  shown here may generally be between about 0.5 mm and about 5.0 mm, more preferably between about 0.5 mm to about 2.5 mm, and most preferably between about 0.5 mm to about 1.0 mm. Similar to the discussion above regarding the diameter of the plurality of cutouts, the diameter d 1  of the plurality of posts  2942  is critical to the proper functionality of the present invention by ensuring proper alignment of the different components without sacrificing feel and weight savings. 
     It should be noted that in this current exemplary embodiment of the present invention the plurality of posts  2942  terminate before reaching the backing portion of the chassis of the golf club head; however, in alternative embodiments of the present invention, the backing portion of the chassis may have a plurality of cutouts corresponding with the same plurality of cutouts  2940  in the lightweight weight adjustment portion  2914 , allowing the plurality of posts  2942  to be longer and extend all the way through to the back surface of the golf club head. Making the plurality of posts longer  2942 , combined with plurality of cutouts extending through both surface, allows the plurality of posts  2942  to be welded to the chassis at the rear surface of the golf club head, creating even more structural rigidity between all of the components without departing from the scope and content of the present invention. 
       FIG. 30  of the accompanying drawings shows an enlarged cross-sectional view of circular region A shown in  FIG. 28 , but in accordance with an alternative embodiment of the present invention wherein the plurality of posts  3042  are formed on the frontal surface of the cavity  2616  (see  FIG. 26 ) created in the chassis of the golf club head instead of on the rear surface of the striking face  3018  without departing from the scope and content of the present invention. The plurality of cutouts  3040  are still formed in the lightweight weight adjustment portion  3014 . 
       FIG. 31  of the accompanying drawings shows an enlarged cross-sectional view of the circular region A shown in  FIG. 28 , but in accordance with an even further alternative embodiment of the present invention. In this alternative embodiment of the present invention shown in  FIG. 31 , the plurality of posts  3142  may be placed at both ends of the interface. More specifically, it can be said both the rear surface of the striking face  3118  and the frontal surface of the cavity  2616  (see  FIG. 26 ) contain a plurality of posts  3142  adapted to engage a plurality of cutouts  3140  congruently placed across the lightweight weight adjustment portion  3114 . 
       FIG. 32  of the accompanying drawings shows an enlarged cross-sectional view of the circular region A shown in  FIG. 28 , but in accordance with an even further alternative embodiment of the present invention. In this alternative embodiment of the present invention the sidewalls of the plurality of cutouts  3240  may be angled to create a countersink causing the plurality of posts  3242  to mushroom and expand after the final forging process. The mushrooming of the plurality of posts  3242  due to the countersink geometry on the lightweight weight adjustment portion  3214  can help further secure the striking face  3218  to the lightweight weight adjustment portion  3214  as well as the chassis of the golf club head. It should be noted that before the final forging step, the plurality of posts  3242  may generally look like cylindrical posts, but deform with the countersink after the forging step. Lastly, the countersink in this embodiment of the present invention is generally by angling the sidewall of the plurality of cutouts  3240  by an angle of between about 5° to about 25°, more preferably between about 10° to about 20°, and most preferably about 15°. The angle of the draft of the countersink in the plurality of cutouts  3240 , combined with the dimension of the plurality of posts  3242  is critical to the proper functionality of the present invention because an insufficient amount of draft angle would not create a strong enough bond between the components; while on the other hand, too much draft angle would leave too much of a void to be filled by the plurality of posts  3240 .  FIG. 33  of the accompanying drawings shows the countersink to be placed in an opposite orientation, allowing the plurality of posts  3342  to come from the chassis instead to create the enhanced mechanical lock. Finally,  FIG. 34  of the accompanying drawings shows that the countersink could be on both sides of the lightweight weight adjustment portion  3414 , creating an even better bond across all of the components. 
       FIG. 35  of the accompanying drawings shows an exploded perspective view of a golf club head  3500  in accordance with an alternative embodiment of the present invention wherein the lightweight weight adjustment portion  3514  and the high density weight adjustment portion  3515  may come in different shapes and be placed at different locations on the golf club head  3500 . In this alternative embodiment of the present invention, the lightweight weight adjustment portion  3514  may be smaller and the heavy density weight adjustment portion  3515  may be placed directly below the lightweight weight adjustment portion  3514  in the center of the golf club head  3500 . This embodiment may be preferred when the adjustment of center of gravity is not as dramatic, and the moment of inertia of the golf club head  3500  does not need to be increased as dramatically. Obviously, the one or more cavities  3516  remain in proportion to the number of weight adjustment portions that is needed, and the striking face  3518  continue to be used to cover the frontal portion of the golf club head  3500 . 
       FIG. 36  of the accompanying drawings shows an exploded perspective view of a golf club head  3600  in accordance with a further alternative embodiment of the present invention. This embodiment of the present invention is slightly different from the prior discussion in that the heavy density weight adjustment portion  3615  may be placed in a cavity  3616  above the location of the lightweight weight adjustment portion  3614  to achieve a higher center or gravity location without departing from the scope and content of the present invention. 
       FIG. 37  of the accompanying drawings shows a graphical chart of the ultimate goal of using these extreme geometries in an iron or wedge to help achieve center of gravity locations that are previously not achievable. In addition to the above,  FIG. 37  of the accompanying drawings shows an innovative method of measuring the center of gravity location of a golf club head that yields a more consistent result. The prior art generally determines the center of gravity of a golf club head based on its location relative to the ground plane. This conventional methodology is useful in providing a basis for measuring golf club head characteristics across all platforms. However, in an iron type golf club setting, where the bounce of the golf club head may significantly change the location of the golf club head itself relative to the ground plane, the conventional methodology may yield inconsistent results. Hence, the present invention seeks to eliminate that undesirable variable by creating an innovative method of determining and designing a golf club head center of gravity location by focusing on the leading edge of the golf club head. 
     Referring back to  FIG. 37 , we can see that CG location line  3751  refers to the prior art CG location of a golf club head through different lofts and different bounces relative to the ground plane. Although the data series forms a general trend, different sole bounces create significant outlier in the data, making it undesirable. However, looking at the same set of golf club heads by measuring the CG location relative to the leading edge  3752  yields even more inconsistency. Hence, in order to address this issue of inconsistency, the present invention seeks to maintain the CG location of a golf club head relative to the ground plane consistent throughout a specific loft, irrespective of bounce. Achievement of this goal is generally accomplished by using the construction described above in  FIGS. 1-36 , and will yield a CG location chart shown by data series  3753  shown in  FIG. 37 . As it can be seen in  FIG. 37 , the 46 degree wedge will maintain its CG location irrespective of the sole bounce profile, and the same thing goes throughout the entire set of wedges up to loft 64. It should be noted that some lofts that are similar to one another will preserve the same CG height location relative to the leading edge as its neighboring lofts to create a consistency irrespective of which wedge combination the golfer selects. Alternatively speaking, it can be said that if the first loft and the second loft are substantially the same, then the first CG height location from the leading edge and the second CG height location from the leading edge are also the same.  FIG. 37  also shows data series  3754 , illustrating how the design intent of the current invention will yield a result under the conventional measurement methodology, but that obsolete measurement method is no longer a concern of the present invention. 
       FIG. 38  of the accompanying drawings shows a graphical representation of a CG locations throughout a set of high lofted golf club heads in accordance with a further alternative embodiment of the present invention. Similar to the previous discussion in  FIG. 37 , this embodiment further improves upon the previous premise that controlling the CG of a golf club head is important, but measuring and controlling that number from the correct reference point is even more crucial. In the previous embodiment of the present invention we have already established that the measurement of the CG from the leading edge is a dramatic improvement over the measurement of the CG from the ground plane. In addition to the above, the discussion regarding  FIG. 37  also established that if the CG location relative to the leading edge can be controlled when offering golf clubs of the same bounce, it greatly improves consistency of performance. 
     The present invention takes that premise even further in order to create a set of golf clubs with a consistent CG location relative to the leading edge throughout the entire set of golf clubs. Focusing the attention on  FIG. 38  we can see that the current inventive golf club head has data series  3853  showing that the CG location relative to the leading edge plane is constant irrespective of the loft and bounce angle of the golf club head. More specifically, all golf clubs in accordance with the present invention will have a CG to leading edge height of between about 14.0 mm to about 15.0 mm, more specifically between 14.0 mm to about 14.5 mm, and more specifically about 14.2 mm. With this being the controlling variable, the CG location relative to the ground plane of the current invention is shown by data series  3854  and jumps randomly throughout the set. This is a significant improvement over the prior art golf club heads, where data series  3851  and  3852  shows the CG locations relative to ground and leading edge respectively, because no attention has been paid to the relationship of CG locations throughout a set of golf clubs. 
     Having a consistent CG location relative to the leading edge throughout a set of golf clubs is beneficial, as it will yield consistent results for the golfer irrespective of which club they choose. However, even more important than creating this consistency throughout the set of clubs is the ability to calibrate that consistency off the correct reference point. In the present invention, data series  3853  reflects this new innovative approach, and has created a consistent CG height relative to the leading edge of the golf club head irrespective of the golf club head loft and bounce angle. Alternatively speaking, it can be said that the set of golf clubs can be comprised out of two or more golf clubs, wherein the CG height location relative to the leading edge is the same irrespective of the loft and or bounce angle of the golf club head. 
     Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the preceding specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting form the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used. 
     It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.