Capability of tungsten carbide micro-mills to machine hardened tool steel

The aim of this study is to optimize micro-mills and their conditions of use to manufacture plastic injection molds in hardened tool steels by micro-milling. The presented results deal with the test of four types of tungsten carbide square end micro-mills in elementary operations with different feed rates and cutting speeds in order to analyze the evolution of cutting forces, cutting stability, tool life, tool wear, surface roughness and burs formation. This experimental approach allows highlighting the influence of cutting conditions, especially feed rate, on burr formation and tool life. This analysis shows a correlation between the micro-mills characteristics (geometry, composition of tungsten carbide) and their wear behavior. Moreover, some dynamic aspects of the micro-milling process are underlined through the influence of cutting speed on cutting stability. This type of experimental study is suitable for the optimization of the tool edge geometry and it reveals the need to develop a predictive model adapted to micro-milling to optimize the dynamic behavior of the tool.