Molds and methods to control mold surface quality

Abstract

A method for treating a mold includes grinding an outer metal surface of a mold body of the mold with a first material; lapping the outer metal surface after the grinding with a second material that is finer than the first material; and polishing the outer metal surface after the lapping to achieve an average surface roughness (Ra) less than or equal to about 0.15 μm and a waviness height (Wa) less than or equal to about 100 nm. A mold for shaping glass-based material can include a mold body having an outer metal surface, wherein the outer metal surface has an average surface roughness (Ra) less than or equal to about 0.15 μm and a waviness height (Wa) less than or equal to about 100 nm.

We claim: 
     
         1 . A method for treating a mold, the method comprising:
 grinding an outer metal surface of a mold body of the mold with a first material;   lapping the outer metal surface after the grinding with a second material that is finer than the first material; and   polishing the outer metal surface after the lapping to achieve an average surface roughness (R a ) less than or equal to about 0.15 μm and a waviness (W a ) less than or equal to about 100 nm.   
     
     
         2 . The method of  claim 1 , wherein the mold body comprises:
 at least 90% nickel by weight; and   at least one of titanium, aluminium, zirconium, silicon, manganese, or cerium, wherein a sum of a weight percent of titanium, aluminium, zirconium, silicon, manganese and cerium is in a range from about 0.6% to about 1%.   
     
     
         3 . The method of  claim 2 , wherein the mold body comprises at least 99% nickel by weight. 
     
     
         4 . The method of  claim 1 , wherein the first material comprises an abrasive having a grit size in a range from about 600 to about 1200. 
     
     
         5 . The method of  claim 1 , wherein the second material comprises an abrasive having a grit size in a range from about 800 to about 1500. 
     
     
         6 . The method of  claim 1 , wherein polishing comprises using a paste having particles with a mean particle size in a range from about 6 μm to about 14 μm. 
     
     
         7 . The method of  claim 1 , wherein one or more of the grinding, lapping, and polishing is performed in a random motion. 
     
     
         8 . The method of  claim 7 , wherein the random motion is circular. 
     
     
         9 . The method of  claim 1 , wherein the average surface roughness (R a ) is in a range from about 0.04 μm to about 0.15 μm. 
     
     
         10 . The method of  claim 1 , wherein the average surface roughness (R a ) is in a range from about 0.06 μm to about 0.1 μm. 
     
     
         11 . The method of  claim 1 , wherein the waviness (W a ) is less than or equal to 40 μm. 
     
     
         12 . The method of  claim 1 , further comprising oxidizing the outer metal surface after polishing to produce a metal oxide layer, wherein the metal oxide layer has a surface roughness (R a ) less than about 1 μm and waviness (W a ) less than about 500 nm. 
     
     
         13 . The method of  claim 12 , wherein the metal oxide layer includes a plurality of grains and the plurality of grains has an average grain size of about 300 μm or less. 
     
     
         14 . The method of  claim 13 , wherein the metal oxide layer includes least one grain body area and at least one grain boundary area and wherein an average height differential between the at least one grain body area and the at least one grain boundary area is about 2 μm or less. 
     
     
         15 . The method of  claim 12 , further comprising doping the outer metal surface at least one of titanium, aluminium, zirconium, silicon, manganese, or cerium after polishing and prior to oxidizing. 
     
     
         16 . The method of  claim 1 , further comprising doping the outer metal surface at least one of titanium, aluminium, zirconium, silicon, manganese, or cerium after polishing.