Carbide and ceramic tool life in high speed turning

Five different types of commercially available inserts have been used to turn an AISI 4340 steel at speeds between 300 m/min and 1,000 m/min. The flank wear was measured for different inserts in connection to cutting time and for different values of cutting speed. It is shown that for carbide tools, an increase in cutting speed causes higher decrease of tool life. This is due to the thin width of the coat layer, and once the coating film is peeled off, the soft substrate of the insert becomes uncovered and the wear grows rapidly. For ceramic insert, the tool life takes high values even for high values of cutting speed. Tool life is defined using wear criterion value, which depends on cutting speed. The investigation included the realisation of wear model in relation to the time. Also, empirical model have been developed for tool life determination in connection with cutting speed. On the basis of obtained results, it is possible to set optimal conditions to achieve the maximum tool life.