Development of a variable flow stress machining theory for aluminium alloys

This paper describes the development of a variable flow stress predictive machining theory for aluminium alloys. This theory is based on the Oxley's machining theory which allows for the high strain-rate/high temperature flow stress and thermal properties of the work materials and has so far been applied and tested for plain carbon steels. The developed predictive theory for aluminium has been applied in predicting cutting forces, chip thicknesses, etc., for a wide range of cutting conditions (cutting speeds ranging from 100 to 1000 m/min) when machining two alloys: one with 97.64%Al and the other with 93.89%Al (a free machining aluminium alloy). The flow stress properties required in applying the predictive method were obtained from bar turning test results and by applying the machining theory in reverse. For the above mentioned aluminium alloys, a comparison between predicted and experimental cutting force results shows good agreement.