A short-time method for the assessment of the machinability of low carbon free machining steels

Abstract

The machinability of 14 casts of low carbon free machining steel has been measured by an extensive study of the wear of M2 High Speed Steel tools, based on the International Standards Organisation (I.S.O.) testing procedure. A consideration of the characteristic wear curves of these tools shows that flank wear land width prior to catastrophic failure of the tool decreases with increase in cutting speed or flank wear rate. The proposed short-time test is based on the observed tool wear and tool life characteristics. Essentially the test involves the measurement of a portion of the secondary steady wear stage of an M2 cutting tool which can be extrapolated either numerically or graphically to give the time of catastrophic failure of the tool. The test allows tool life to be predicted to better than ± 10 per cent for this class of workpiece machined with M2 High Speed Steel tools.