Investigations on the Nature of Surface Finish and Its Variation With Cutting Speed

An attempt has been made to investigate the nature and cause of the variation of surface finish with cutting speed during orthogonal cutting operations. It is found that the variation of cutting speed alone is sufficient to give rise to the three different mechanisms of chip formation, conventionally known as discontinuous, continuous without “bue” (built-up-edge) and continuous with bue. The transition from low-speed, nonbue cutting to high-speed, bue cutting is found to greatly influence the surface finish and in fact the entire cutting mechanism. Photomicrographs of the cutting zones, the chips, and the profiles of the finished surfaces have been taken to observe these changes closely. Tests have also been carried out to determine the relative importance of cutting speed and cutting temperature in affecting the surface finish of the workpiece being machined.