Machinability of P/M Parts - Effect of Machining Additives and Processing

摘要

Despite P/M's advantage in near net shape processing, many parts require secondary machining operations either because their geometry will not allow features to be incorporated in the pressing direction or due to tight tolerance requirements. A case in point is parts that are used in VCT applications, the overall cost of which is greatly affected by the machining costs. In order to improve the machinability of P/M materials, machining additives are incorporated in the powder by admixing. The objective of this study is to examine the effect of machining additive, sintering cooling rate, heat treatment and oil impregnation on tool wear and burr formation. The materials evaluated are: FC0208 in both as sintered, sinter hardened and heat treated conditions. Machinability was evaluated by turning and drilling tests. Results are characterized by tool wear, surface finish, burr size, microstructure and SEM analysis.