Cryogenically Treated Round Silicon Carbide Whisker-Reinforced Alumina Inserts for Face Milling Hardened Steel

One of the most cost-effective dimensionally accurate processes used in manufacturing today, that is capable of producing a superior surface finish, is machining. As tooling wears, however, the advantages of machining greatly diminish. In addition, the time lost changing out the tooling significantly affects the overall process efficiency. Therefore, methods that decrease the wear rate of tooling and, thereby, increase tool longevity is essential to improving the efficiency of machining. Cryogenically treating tooling is one method that has been demonstrated to significantly increase the wear resistance of traditional tooling materials such as steel and tungsten carbide and is becoming more commonplace in industry. However, the effects of cryogenically treating advanced ceramic tooling are not well established, especially for machining hardened steels and refractory metals. In addition, round geometry inserts were studied due to the rising popularity in industry, since there are an increased number of cutting edges. To help establish these effects, in this work, commercial grade silicon carbide whisker-reinforced alumina cutting inserts, WG-300, were subjected to deep cryogenic temperatures at −170°C. Face milling was conducted on AISI O1 hardened steel of 55 HRC to evaluate the cryogenic treatment’s effects on the wear of the ceramic inserts. More specifically, tool life and surface finish were analyzed to evaluate the performance improvements of the treated tooling. This study found that the flank wear of the deep cryogenically treated ceramic inserts was less than the corresponding wear of the untreated ceramic inserts. In addition, the surface finish produced by the treated ceramic inserts was finer than that of the untreated ceramic inserts.