A Study on the Origin of Surface Roughness During the Finish Turning of 0.45% Carbon Steel with a Carbide Tool

The origins of surface roughness are studied during the finish turning of 0.45% carbon steel with a carbide tool. The existence of micro built-up-edge, the profile of chip surface and machined surface, and the wear grooves on the minor flank of the tool are measured at some interval during the test run. The primary origin of surface roughness changes with tool wear in the order of i) micro built-up-edge, ii) wear groove and rarely existing micro built-up-edge, iii) wear groove and self-excited vibration of tool. Small surface roughness (Rmax=1.5 μ) is produced between the stage ii) and iii) when a machine tool having high dynamic stiffness is used.At the statge of stationary tool wear rate, the transcription of wear groove of tool to the work surface plays main roles in the surface roughness formation. Therefore it is duely expected that the surface with small surface roughness can be produced by turning under the condition which does not produce deep groove wear.