A new concept for decoupling the cutting forces due to tool flank wear andchip formation in hard turning

Determining the temperature field in metal cutting when the tool flank is p rogressively worn requires the knowledge of the forces due to tool flank we ar and that due to chip formation. In the past, these forces have been comp uted from data experimentally measured with a dynamometer, under the assump tion that the chip formation configuration remained unaltered when the tool flank is progressively worn. This approach has been used in the literature even though there has been evidence that it is not correct. The error intr oduced by this doubtful assumption in computing the maximum surface tempera ture in the workpiece can be significant. Of late there has been considerable interest in employing hard turning as t he final finishing process in place of grinding and superfinishing. Consequ ently, the ability to accurately predict the maximum surface temperature an d its distribution in the workpiece is now most desirable, for avoiding the rmal damage to the machined surface. This paper discusses a new method base d on the thickness of the microstructural change in chips to decouple the t ool-flank forces for predicting the maximum surface temperature and its dis tribution in the workpiece.