Cutting parameter optimization in shoulder milling of commercially pure molybdenum

Abstract

Due to its superior properties such as high melting point (2617°C), high thermal conductivity and low thermal expansion at higher temperatures, molybdenum is a refractory metal and is used for making critical parts in defense, space, electronics and nuclear industries. High cost of molybdenum makes the selection of suitable cutting conditions imperative in machining operations in order to obtain the required surface quality and dimensional accuracy. In this study, suitable cutting tools and cutting parameters were aimed to be determined in terms of cutting forces (F c) and average surface roughness (R a) when shoulder milling commercially pure molybdenum. The milling tests were carried out at 0.05, 0.1, 0.15, 0.2 mm/tooth feed rates and 75, 100, 125, 150 m/min cutting speeds using four different cutting tools. The Taguchi's experimental design (L16 orthogonal array) technique was implemented. Analysis of variance was used to determine the effects of cutting tools and cutting parameters on R a and F c. The results showed that the feed rate is the most influential parameter for F c while the cutting speed is for R a. Keywords Pure molybdenum Á ANOVA Á Surface roughness Á Cutting forces List of symbols a p Radial depth of cut (mm) a e Axial depth of cut (mm) A 0 Optimum S/N ratio for A (cutting tool) (dB) B 0 Optimum S/N ratio for B (feed rate) (dB) C 0 Optimum S/N ratio for C (cutting speed) (dB) CI Confidence interval f Feed rate (mm/tooth) F c Main cutting force (N) N Total number of tests g G S/N ratio calculated at optimum level (dB) g G S/N averages of control factors (dB) n eff Confirmatory test number R a Average surface roughness (lm) S/N Signal/noise ratio (dB) V c Cutting speed (m/min) V e Error variance

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