Compensation for Merchant’s Circle Diagram to predict cutting force in orthogonal micro turning

Cutting force for conventional orthogonal machining can be predicted by Merchant’s Circle Diagram (MCD) considering the shearing action of chip formation. However, the effect of plowing action is significant for micro turning, which has not been considered in MCD. Therefore, a large error has been observed in the prediction of cutting force in micro turning by MCD theory. In this study, a compensated model has been developed for orthogonal micro turning based on MCD. The theory has taken shearing and plowing actions into consideration. The compensated model involved material flow stress, cutting parameters, and tool geometry, including cutting edge radius. This model has predicted tangential cutting force with an average prediction error of 3.75% for micro turning of Ti6Al4V, whereas the average prediction error was 14.9% for axial cutting force.