A NEW CONCEPT FOR DECOUPLING THE CUTTING FORCES DUE TO TOOL FLANK WEAR AND CHIP FORMATION IN HARD TURNING

Determining the temperature field in metal cutting when the tool flank is progressively worn requires the knowledge of the forces due to tool flank wear and that due to chip formation. In the past, these forces have been computed from data experimentally measured with a dynamometer, under the assumption 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 introduced by this doubtful assumption in computing the maximum surface temperature in the work-piece can be significant.

Of late there has been considerable interest in employing hard turning as the final finishing process in place of grinding and superfinishing. Consequently, the ability to accurately predict the maximum surface temperature and its distribution in the workpiece is now most desirable, for avoiding thermal damage to the machined surface. This paper discusses a new method based on the thickness of the microstructural change in chips to decouple the tool-flank forces for predicting the maximum surface temperature and its distribution in the workpiece.