Golf club head having a multi-material face

Abstract

A golf club with a multi-material face is disclosed herein. More specifically, the golf club head in accordance with the present invention has a striking face that forms a pocket, wherein the pocket is filled with a secondary material having a lower density to improve the performance of the golf club head. The multi-material face disclosed in accordance with the present invention may generally have a characteristic time slope of greater than about 5 and less than about 50, wherein the characteristic time slope is determined based on the various data points collected according to the United States Golf Association's (USGA's) Characteristic Time (CT) test.

What is claimed is: 
     
         1 . A golf club head comprising:
 a hollow unitary shell, made out of a first material having a first density, forming at least one opening near a frontal portion of said golf club head;   a striking face portion at said frontal portion of said golf club head made out of a second material having a second density, wherein a central portion of said striking face portion creates a pocket, and   a face insert, made out of a third material having a third density, located within said pocket,   wherein said second density is less than said third density, and   wherein said striking face creates a return portion at least partially around a perimeter of a striking surface.   
     
     
         2 . The golf club head of  claim 1 , wherein said return portion does not encompass a hosel portion of said golf club head. 
     
     
         3 . The golf club head of  claim 2 , wherein said second density is less than about 2.7 g/cm 3  and said third density is greater than about 4.0 g/cm 3 . 
     
     
         4 . The golf club head of  claim 3 , wherein said striking face has a striking thickness ratio of less than about 1.0. 
     
     
         5 . The golf club head of  claim 4 , wherein said striking face has a striking thickness ratio of less than about 0.8. 
     
     
         6 . The golf club head of  claim 5 , wherein said striking face has a striking thickness ratio of less than about 0.7. 
     
     
         8 . The golf club head of  claim 3 , wherein a depth of said pocket is greater than about 0.2 mm and less than about 2.0 mm. 
     
     
         9 . The golf club head of  claim 8 , wherein a depth of said pocket is greater than about 0.5 mm and less than about 1.5 mm. 
     
     
         10 . The golf club head of  claim 9 , wherein a depth of said pocket is about 1.0 mm. 
     
     
         11 . The golf club head of  claim 3 , wherein said return portion has a thickness of less than about 1.0 mm. 
     
     
         12 . The golf club head of  claim 11 , wherein said return portion has a thickness of less than about 0.8 mm. 
     
     
         13 . The golf club head of  claim 12 , wherein said return portion has a thickness of less than about 0.7 mm. 
     
     
         14 . The golf club head of  claim 3 , wherein said second material is a carbon fiber based composite material. 
     
     
         15 . A golf club head comprising:
 a hollow unitary shell, made out of a first material having a first density, forming at least one opening near a frontal portion of said golf club head;   a striking face portion at said frontal portion of said golf club head made out of a second material having a second density, wherein a central portion of said striking face portion creates a pocket, and   a face insert, made out of a third material having a third density, located within said pocket,   wherein said second density is less than said third density,   wherein said striking face creates a return portion at least partially around a perimeter of a striking surface, and   wherein said return portion has a distance greater than about 10 mm.   
     
     
         16 . The golf club head of  claim 15 , wherein said return portion has a distance of greater than about 15 mm. 
     
     
         17 . The golf club head of  claim 16 , wherein said return portion has a distance of greater than about 25 mm. 
     
     
         18 . The golf club head of  claim 15 , said second density is less than about 2.7 g/cm 3  and said third density is greater than about 4.0 g/cm 3 . 
     
     
         19 . The golf club head of  claim 18 , wherein said golf club head has a first peak frequency to volume ratio of greater than about 7.0 hertz/cc and less than about 15.0 hertz/cc; said first peak frequency to volume ratio is defined as a first peak frequency of a signal power diagram of the sound of said golf club head as it impacts a golf ball, divided by a volume of said golf club head. 
     
     
         20 . The golf club head of  claim 19 , said second material is a composite material, having a strain to failure percentage of greater than about 1.5% and less than about 10.0%.