Investment-casting of thin-walled golf club-heads

Abstract

Investment-casting shells are disclosed that have at least one cluster of individual club-head casting molds for casting thin-walled, steel or steel-alloy club-heads at high process yield and low material usage. The shells have respective combinations of cluster configuration and number, gating, and runners, as determined systematically. Some shell configurations include a cluster of at least ten casting molds for respective club-heads each (a) having a head-volume less than 400 cm 3 , (b) defining at least one club-head wall having a thickness of less than 0.8 mm, and (c) defining at least one respective gate. The cluster is configured to produce a cast-product yield of greater than 80% at a material usage of less than 1,000 g, including process losses, per cast club-head. Also, at least one runner connects the gates together.

We claim: 
     
         1 . An investment-casting shell for investment casting of golf club-heads of steel or steel-alloy, the investment-casting shell comprising:
 a cluster of at least ten casting molds for respective club-heads each having a head-volume less than 400 cm 3 , defining at least one club-head wall having a thickness of less than 0.8 mm, and defining at least one respective gate, the cluster being configured to produce a cast-product yield of greater than 80% at a material usage of less than 1,000 g, including process losses, per cast club-head; and   at least one runner connecting together the at least one respective gate of each mold, wherein the at least one respective gate and at least one runner have an interface gating ratio ranging from 0.7 to 1.3.   
     
     
         2 . The investment-casting shell of  claim 1 , wherein each casting mold defines a respective main gate and at least one respective assistant gate connected to the respective main gate. 
     
     
         3 . The investment-casting shell of  claim 1 , wherein:
 at the casting molds, the respective gates have respective runner-gate interfaces at the at least one respective runner; and   the runner-gate interfaces each have a Reynolds number Re≦6.0×10 5  and each require, during use of the shell for casting steel or steel-alloy club-heads, a minimum force ≦500 Nt.   
     
     
         4 . The investment-casting shell of  claim 1 , wherein the at least one runner has a triangular or rectangular cross-section. 
     
     
         5 . The investment-casting shell of  claim 1 , wherein the at least one runner has less than three turns of 90° or greater. 
     
     
         6 . The investment-casting shell of  claim 1 , further comprising a receptor connected to the at least one runner. 
     
     
         7 . A method for casting steel or steel-alloy club-heads for golf clubs, the method comprising:
 preparing an investment-casting shell comprising at least one cluster of at least ten casting molds for casting respective club-heads each having a head-volume less than 400 cm3, at least one wall having a thickness of less than 0.8 mm, and at least one respective gate, the investment-casting shell being configured to produce a cast-product yield of greater than 80% at a material usage of less than 1000 g, including process losses, per casting mold, the cluster also comprising at least one runner connecting together the gates;   at a preset force, introducing molten steel or steel-alloy into the investment-casting shell and into the at least one cluster; and   flowing the molten steel or steel-alloy in the at least one runner through the gates and into the individual casting molds to fill the casting molds with steel or steel-alloy and thus cast the respective club-heads.   
     
     
         8 . The method of  claim 7 , further comprising rotating the investment-casting shell to at least 200 rpm to produce the preset force. 
     
     
         9 . The method of  claim 8 , wherein the investment-casting shell is rotated in a sub atmospheric pressure to produce the preset force. 
     
     
         10 . The method of  claim 7 , further comprising preheating the investment-casting shell to a temperature of at least 800° C. before introducing the molten steel or steel-alloy into the investment-casting shell. 
     
     
         11 . The method of  claim 7 , wherein the investment-casting shell is prepared such that the gates and at least one runner have an interface gating ratio ranging from 0.7 to 1.3. 
     
     
         12 . The method of  claim 7 , wherein the investment-casting shell is prepared such that the gates have respective runner-gate interfaces at the at least one runner, and the runner-gate interfaces each have a Reynolds number Re≦6.0×10 5 ; and the steel or steel-alloy is introduced into the cluster at a minimum force that is no greater than 500 Nt. 
     
     
         13 . The method of  claim 7 , wherein the investment-casting shell is prepared such that the at least one runner has a triangular or rectangular cross-section. 
     
     
         14 . The method of  claim 7 , wherein the investment-casting shell is prepared such that the at least one runner has less than three turns of 90° or greater. 
     
     
         15 . An investment-casting shell for investment casting of golf club-heads of steel or steel-alloy, the investment-casting shell comprising a cluster of at least four casting molds for respective club-heads each having a head-volume less than 400 cm 3  and defining a least one club-head wall of thickness less than 0.8 mm, the cluster being configured to produce a cast-product yield of greater than 80% at a material usage of less than 1000 g, including process losses, per cast club-head. 
     
     
         16 . The investment-casting shell of  claim 15 , wherein each casting mold defines at least a respective main gate through which molten steel or steel-alloy is introduced into the casting mold. 
     
     
         17 . The investment-casting shell of  claim 16 , further comprising at least one runner connecting together the gates and wherein the gates and at least one runner have an interface gating ratio ranging from 0.7 to 1.3. 
     
     
         18 . The investment-casting shell of  claim 17 , wherein:
 at the casting molds, the respective gates have respective runner-gate interfaces at the at least one respective runner; and the runner-gate interfaces each have a Reynolds number Re≦6.0×10 5  and each require, during use of the shell for casting steel or steel-alloy club-heads, a minimum force ≦500 Nt.   
     
     
         19 . The investment-casting shell of  claim 17 , wherein the at least one runner has a triangular or rectangular cross-section. 
     
     
         20 . The investment-casting shell of  claim 17 , wherein the at least one runner has less than three turns of 90 or greater.