Drastic reduction of costly machining operations is a definite advantage of powder metallurgy. However, due to design constraints, many P/M parts still require some machining. For these applications, the machinability of materials becomes an important parameter of the part manufacturing process.
Test programs have been conducted at Quebec Metal Powders Limited to characterize the machinability of ferrous P/M materials. The effects of sintered density and alloying elements, namely carbon, copper and phosphorus, on the drilling thrust force are presented together with those of machinability enhancing additives such as manganese sulphide and boron nitride. Methods to optimize both strength and machinability of P/M materials are also discussed.