Tool Life And Surface Finish Evaluations In Dry Milling Of AISI D2 Tool Steel

Abstract

Good control and planning of cutting parameters and optimization of cutting conditions requires prediction of tool wear and surface finish. This paper presents a study of tool life and surface finish while machining AISI D2 tool steel. Milling tests were performed under dry cutting condition in order to avoid thermal shock on the brittle carbide tool. Various cutting speed and feed rates were tested while the axial and radial depth of cuts were set to be constant for all trials. Repetitions for each set of cutting condition were made three times and shortest tool life was taken. The results showed that the flank wear starts with an initial stage and it is followed by gradual stage and finally abrupt stage of wear. Mechanical wear or abrasion is typically dominant during the initial cutting. Majority of the tool wear modes were due to flank wear and excessive chipping on the tool edge. Maximum tool life is obtained at a cutting speed of 50 m/min and feed rate of 0.02 mm/rev. The effect of increasing feed rate on tool life is most significant and occurs at the lowest speed of 50 m/min. The life of the cutting tool does not reflect the state of the machined surface where the surface roughness value is still low at the end of the cut. Overall, the machined surface is very smooth with a R_a value of 0.10-0.37 µm. The surface defects identified during the test are voids, chatter marks, abrasion marks, built-up edges and distortions on the feed marks.

Keywords: flank wear, tool life, R_a, dry machining.