CORRELATING TOOL WEAR, TOOL LIFE, SURFACE-ROUGHNESS AND TOOL VIBRATION IN FINISH TURNING WITH COATED CARBIDE TOOLS

Experiments have been carried out in an attempt to monitor the change of workpiece surface roughness caused by the increase of tool wear, through the variation of the vibration in finish turning, under different cutting conditions. The vibration was measured by two accelerometers attached to the tool and the parameter used to make the correlation with surface roughness was the r.m.s. of the signal. The tool of one experiment was photographed at different stages of the cut in order to explain the wear formation and the behaviour of surface roughness as the cutting time elapsed. The material machined was AISI 4340 steel and the tool was coated carbide inserts. The results show that vibration of the tool can be a good way to monitor on-line the growth of surface roughness in finish turning and, therefore, it can be useful for establishing the end of tool life in these operations. Another conclusion is that, when coated tools are used, the behaviour of surface roughness as cutting time elapses is very different from that when uncoated tools are used.