Tool wear and surface finish in high speed machining of steel

High speed machining has the potential to yield excellent surface finish under dry machining conditions and hence is of great technological interest. In finish turning operations, high speed and low feed combinations are used successfully to achieve excellent surface finish so that a subsequent finish grinding operation is eliminated, resulting in substantial cost saving. However, with the increase in cutting speed, there is a change in chip morphology from continuous to fully segmented chip. The effect of low feed and high speed combination is to localize the crater wear closest to the cutting edge of the tool. The loss of cutting edge impairs the surface finish and hence the tool life is reduced. The results from basic research investigations on chip segmentation, tool wear and surface finish will be presented. Prevention of the tribology of seizure by in-situ lubrication through inclusion engineering of the workpiece (steel) is identified as key to suppressing tool crater wear at high cutting speed. This emerging market need represents a new and excellent opportunity for steel industry to develop a new generation of inclusion engineered steel grades designed specifically for high speed machining.