Machinability Parameters in Finish Face Milling of Low Alloy Cr-Ni Steel with THR K30 Carbide Tool Part I: Cutting Forces, Specific Cutting Energy and Temperatures.(Dept.M)

Abstract

It is necessary to ware of the surface alterations that can be produced by grinding operations. This work deals with finish face milling of low alloy steal in its hardness conditions with view to replace surface grinding. This paper is the first of two dealing with the use of submicron grain cemented carbide with low percentage of cubic cabides of 2%. Three major machinability parameters were investigated; cutting force, specific cutting conditions and the minor flank wear on the machinability parameters are investigated. Further, the behaviour of shear angle and normal and shear stresses as well as contact condition on the minor cutting edge were examined. The THR K30 tools were found to be capable of operating at cutting speed up to 176 m/min. Forces with the THR tools are relatively lower than TTM tools at higher cutting speeds. It was also found that the cutting ratio is almost constant at worn minor flank wear of value between 50 to 200 µm. The substantial increase in vertical component Fz, was attributed to the low coefficient of friction of approximate value of 0.4. Descripancies of the findings of the calculated temperatures are also discussed. The specific cutting energy was found to be a constant value of order 2 to 2.5 GJ/m3 at high speeds and feeds respectively. This proved that the finish face milling with THR K30 could be substituted for a vertical spindle surface grinding when judged on the basis of specific cutting energy.