| Traditionally, powder metallurgy technology allowed the production of near net shape components without using secondary shaping operations. However, with the actual diversity of this process, about 30% of all powder metallurgy components require the use of machining operations to satisfy geometrical conformance. Machining these parts, particularly those made from sinter hardenable steel powders, is limited due to the presence of residual porosity after compacting as well as hard phases.; Green machining of powder metallurgy components is an attractive process to lower production costs and to compete with other shaping processes. However, green machining is not a straightforward procedure and requires other considerations than the sole optimization of cutting parameters. Indeed, density gradients in green compacts have a strong influence on the surface finish of the machined parts.; This study presents a new technique, based on cutting force measurements during green turning, to quickly and precisely characterize density gradients in powder metallurgy components. This new technique also allows the characterization of green machinability. Moreover, this study shows that timing sprockets can be produced by green machining of gear blanks. Timing sprockets produced by this process show a surface finish comparable to that of powder metallurgy components machined after sintering.; An article summarizing the principal results of this study has been submitted to the journal Materials Science Engineering A. This article is presented in annex 1. |
