Determination of tool friction in presence of flank wear and stress distribution based validation using finite element simulations in machining of titanium and nickel based alloys

Abstract

Tool friction plays a very important role in machining titanium and nickel-based alloys and is an important parameter in Finite Element based machining simulations. It is the source for the high amount of heat generation, and as a result, the excessive flank wear during machining these materials. The worn tool is known to create poor surface qualities with high tensile surface residual stresses, machining induced surface hardening, and undesirable surface roughness. It is essential to develop a methodology to determine how and to what extent the friction is built up on the tool. This study facilitates a determination methodology to estimate the stress distributions on the rake and flank surfaces of the tool and resultant friction coefficients between the tool and the chip on tool rake face, and the tool and the workpiece on tool flank face. The methodology is applied to various tool edge radii and also utilized in solving stagnation point location on the tool edge. Predicted friction results are further validated with comparison of predicted stress distributions from FE simulations for machining of titanium alloy Ti-6Al-4V and the nickel-based alloy IN-100. It was found that tool stresses and friction are mainly influenced by tool rake angle, edge radius, and tool flank wear and are slightly affected by the cutting conditions in the ranges that were considered in this study.