15.6.2016 Pressing & Sintering

The effect of porosity on machinability of PM materials

One of the distinct features of powder metallurgy (PM) material is porosity. Depending on the application, this can be advantageous or a disadvantage. While density levels may be kept low in bearing applications, structural parts requiring high strength will maximize density in order to meet mechanical properties. The geometry of the component being compacted will influence not only the overall density level, but also the consistency of the density throughout the component. PM materials are considered more difficult to machine due to the porosity. While it is generally accepted that porosity negatively impacts machinability of PM steels, detailed works generally lack on the relationship between porosity and machinability, especially when a machinability enhancer is utilized. In this study, machinability of the popular iron-copper-carbon steel was evaluated at different density levels. Commercial machining enhancing additives were examined in the study to determine the effect of density (or porosity) level on their overall effectiveness.