Mechanical and Chemical Surface Treatment of a Golf Club Head

Abstract

Described herein is a method for treating a metallic golf club head in a series of post-assembly steps, to provide a hardened dark coating. The method described herein includes a quench-polish-quench (QPQ) process that results in a surface coating with improved hardness, uniformity, and porosity characteristics, thereby reducing visible surface deformation and durability loss.

1 . A method for treating a golf club head, the method comprising:
 (a) aging a nitriding salt in a first furnace for a predetermined amount of time;   (b) blasting an outer surface of the golf club head;   (c) placing a holding fixture in a second furnace and heating the second furnace to a predetermined temperature for a predetermined amount of time;   (d) moving the holding fixture from the second furnace to the first furnace and allowing the holding fixture to remain in the first furnace for a predetermined amount of time,
 wherein a nitride layer is formed on the outer surface; 
   (e) lowering the temperature of the first furnace to a predetermined temperature for a predetermined amount of time,
 wherein a first oxide layer grows on top of the nitride layer; 
   (f) removing the holding fixture from the first furnace, cooling the golf club head to a predetermined temperature, cleaning the golf club head, and unloading the golf club head from the holding fixture;   (g) blasting the outer surface of the golf club head;   (h) placing the holding fixture in the second furnace and heating the second furnace to a predetermined temperature for a predetermined amount of time;   (i) moving the holding fixture from the second furnace to the first furnace and allowing the holding fixture to remain in the first furnace for a predetermined amount of time,
 wherein a second oxide layer grows on the first oxide layer; 
   (j) removing the holding fixture from the first furnace, cooling the golf club head to a predetermined temperature, and cleaning the golf club head; and   (k) blasting the outer surface of the golf club head, wherein the nitride layer, the first oxide layer and the second oxide layer are uniform.   
     
     
         2 . The method of  claim 1 , wherein the nitriding salt comprises a CNO concentration between 28% and 36%. 
     
     
         3 . The method of  claim 1 , wherein the blasting of step (b) is performed with a 220 #grit glass bead. 
     
     
         4 . The method of  claim 1 , wherein the nitride layer comprises a nitride thickness between 0.00025 inches and 0.00060 inches. 
     
     
         5 . The method of  claim 4 , wherein the nitride layer comprises a nitride max thickness and nitride min thickness;
 wherein the nitride max thickness is between 0.00025 inches and 0.00045 inches, and the nitride min thickness is between 0.00045 inches and 0.00060 inches.   
     
     
         6 . The method of  claim 5 , wherein the nitride layer comprises a nitride uniformity that is less than 1.25. 
     
     
         7 . The method of  claim 1 , wherein the first oxide layer comprises a first oxide thickness is less than 0.000115 inches. 
     
     
         8 . The method of  claim 7 , wherein the first oxide layer comprises a first oxide max thickness and first oxide min thickness,
 wherein the first oxide max thickness is between 0.000075 inches and 0.000115 inches, and the first oxide min thickness is between 0.000050 inches and 0.000075 inches.   
     
     
         9 . The method of  claim 8 , wherein the first oxide layer comprises a first oxide uniformity that is less than 1.85. 
     
     
         10 . The method of  claim 1 , wherein the second oxide layer comprises a second oxide thickness is less than 0.000115. 
     
     
         11 . The method of  claim 10 , wherein the second oxide layer comprises a second oxide max thickness and second oxide min thickness;
 wherein the second oxide max thickness is between 0.000075 inches and 0.000115 inches, and the second oxide min thickness is between 0.000050 inches and 0.000075 inches.   
     
     
         12 . The method of  claim 11 , wherein the second oxide layer comprises a first oxide uniformity that is less than 1.65. 
     
     
         13 . A golf club head comprising:
 a body having a top rail opposite a sole, a toe opposite a heel;   a hosel coupled to the club body and having a first end proximate the heel and a second end opposite the first end;   an outer surface comprising a QPQ finish;
 wherein the QPQ finish comprise a nitride layer, a first oxide layer, and a second oxide layer; 
 wherein the outer surface comprises a grade 3 QPQ finish; 
 wherein the nitride layer comprises a nitride uniformity between 1.00 and 1.25;
 wherein the first oxide layer comprises a first oxide uniformity between 1.00 and 1.25; and 
 wherein the second oxide layer comprises a second oxide uniformity between 1.00 and 1.25. 
 
   
     
     
         14 . The golf club head of  claim 13 , where the QPQ finish has a hardness between 55 HRS and 65 HRC. 
     
     
         15 . The golf club head of  claim 13 , wherein the nitride layer comprises a nitride thickness between 0.00025 inches and 0.00060 inches. 
     
     
         16 . The golf dub head of  claim 13 , wherein the nitride layer comprises a nit ride max thickness and nitride min thickness; and
 wherein the nitride max thickness is between 0.00025 inches and 0.00045 inches and the nitride min thickness is between 0.00045 inches and 0.00060 inches.   
     
     
         17 . The golf club head of  claim 13 , wherein the first oxide layer comprises a first oxide thickness is less than 0.0001115 inches. 
     
     
         18 . The golf club head of  claim 13 , wherein the first oxide layer comprises a first oxide max thickness and first oxide min thickness,
 wherein the first oxide max thickness is between 0.000075 inches and 0.000115 inches, and the first oxide min thickness is between 0.000050 inches and 0.000075 inches.   
     
     
         19 . The golf club head of  claim 13 , wherein the second oxide layer comprises a second oxide thickness is less than 0.000115. 
     
     
         20 . The Of club head of  claim 13 , wherein the second oxide layer comprises a second oxide max thickness and second oxide min thickness;
 wherein the second oxide max thickness is between 0.000075 inches and 0.000115 inches, and the second oxide min thickness is between 0.000050 inches and 0.000075 inches.