Micromilling of hardened (62 HRC) AISI D2 cold work tool steel

摘要

Investigations into micro-slot milling of high carbon, high chromium hardened AISI D2 cold work tool steel using 0.5mm diameter coated (TiAlN) tungsten carbide end mills were carried out. Performance was assessed in terms of tool life/tool wear, surface roughness, cutting forces, burr formation, slot geometry accuracy and workpiece surface integrity. The influence of operating parameters (cutting speed, feed rate and depth of cut) on tool life, surface roughness, burr width and cutting forces was evaluated using full factorial experiment design. Analysis of results included main effects plot and calculation of percentage contribution ratios (PCR) for each of the primary variable factors and their interactions were assessed via analysis of variance (ANOVA). The test array was further extended to allow for implementation of Response Surface Methodology (RSM) analysis in order to optimise tool life and surface roughness. Dual-response (cutting speed and feed rate) contours of metal removal rate and tool life/surface roughness were generated from the respective model equations. These were further developed to identify combinations of cutting speed and feed per tooth for the best tool life/surface roughness at specific metal removal rates. Finally, the impact of coatings and tool geometry on tool life and workpiece surface roughness was investigated.