Optimal machining parameters selection in high speed milling of hardened steels for injection moulds

High speed machining is a cost effective method of machining hardened steels for injection moulds. Recent works of the hardened steel machining industry suggests that substantial gains in productivity can be realised by better part programming and by better utilisation of machine tools machining parameters. Dimensional precision and surface quality are the two key factors, which determine the quality of manufactured parts. Machining parameters such us spindle speed, feed per tooth (mm/z), axial depth of cut and radial depth of cut deeply affect both dimensional precision and surface quality. Therefore, an optimal selection of these manufacturing parameters is very important in order to obtain high precision parts and to reduce the manual fit operations and the cost. This paper presents a mathematical modelling of the surface roughness in high speed milling of hardened steels for injection moulds using design of experiments. These models will allow us to determine in advance the surface quality of manufactured parts, obtained by high speed milling processes using the technique of design of experiments (DOE) which allows us, by only performing a small number of experiments, to select the optimal machining conditions so that meet manufacturing specifications.