A study of the effects of friction on flank wear and the role of friction in tool wear monitoring

Abstract

Tool wear is the most commonly observed and unavoidable aspect of metal cutting. The worn tools adversely affect the surface finish of the workpiece, and they can be replaced in time if a tool wear monitoring system is used. During turning, the freshly generated workpiece surface comes into contact with the flank face and friction takes place at the interface. As a result of friction, flank wear occurs. Increasing flank wear results in an increase in the contact area at the flank-workpiece interface. This in turn increases the coefficient of friction, and due to this, stick slip vibration is likely to occur. The modelling of such a system is carried out in this paper. The friction at the flank-workpiece interface is still considered as complex, but the occurrence of stick-slip as a result of flank wear can be utilised to develop tool wear monitoring systems. Most studies regarding friction in metal cutting are limited to the tool-chip interface. This paper outlines a method to correlate flank wear and friction. The equations of motion of the cutting tool are derived considering stick-slip friction taking place at the flank-workpiece interface, and the resulting forces acting on the tool flank are correlated with flank wear. The effect of friction on the tool flank wear is studied using MATLAB simulations and an increase in the amplitude of tool vibration, worn tool cutting forces and coefficient of friction with increasing flank wear were observed. The relationship between the friction and the tool wear derived here can be used to carry out effective tool condition monitoring and tool life prognosis.