Effect of machine tool’s spindle forced vibrations on surface roughness, dimensional accuracy, and tool wear in vertical milling of AISI P20

Abstract

This paper reports on the effects of spindle attributed forced vibrations on machinability characteristics of vertical milling process. The effects of three levels of spindle attributed forced vibrations along with feed rate and axial depth of cut are evaluated on surface roughness, dimensional accuracy, and tool wear under constant conditions of radial depth of cut and cutting speed. AISI P20 and solid carbide cutter are used as workpiece material and tool, respectively. Taguchi L9 standard orthogonal array is used for experiments followed by analysis of variance (ANOVA) for identifying significant parameters that affect surface roughness and dimensional accuracy. Tool wear in terms of crater wear (Kt) and tool flank wear (VBmax) is measured along with an analysis of chipping and built-up edges for accessing the influence of forced vibrations. It is found that machine tool vibration amplitude and axial depth of cut are statistically significant at 95 % confidence level for surface roughness, with vibration amplitude being the most contributing factor (83.4 %) followed by axial depth of cut (12.39 %). The dimensional accuracy is found to be insensitive to the parameters at stated confidence level. Higher values of vibration amplitude and feed rate are found to be resulting into excessive tool wear with vibration amplitude of 0.185929 mm/min combined along with a feed rate of 600 mm/min and an axial depth of cut of 0.15 mm resulting in catastrophic tool failure.