Machining Powder Metallurgy Materials.

摘要

Powder metallurgy (P/M) products eliminate the need for most machining; however, many P/M Components do require some machining and little is known about the machinability of these materials. Toward providing guidelines for machining P/M materials, machining tests were conducted on low and high density P/M steel (AISI 4640) specimens. Results of these tests are presented along with data on conventionally wrought AISI 4140 steel. The preference for low alloy steels in the manufacture of weapon components led to the choice of these materials for the investigation. Significant differences in cutting forces were experienced in the cutting of high and low density P/M materials. The maximum practical cutting speed in drilling was higher for low density P/M material than that for high density material. Tool wear in the reaming of P/M materials was negligible. In drilling, improvement of hole geometry by sequential machining operations varied greatly. Boring with a rigid bar gave the best geometry. Hardness of the material had decisive effect on machinability. Relatively burr-free holes could be drilled in P/M materials. Overall machinability of the investigated materials did not show significant differences. (Author)