Tool wear of corner continuous milling in deep machining of hardened steel pocket

Pocket molds are widely applied, whose pockets usually contain many transition corners. The machining efficiency of pocket mold can be improved significantly through deep milling. However, tools are subject to quick wear and damage during corner deep milling. Corner rounding along tool path by different approaches has great influence on the tool wear in deep milling of hardened steel pocket mold. Therefore, conducting related researches on tool wear is of practical significance. Firstly, continuous cutting pocket molds were designed for typical corners of different corner rounding approaches as per the basic theory of tool engagement angle in milling, and then hardened steel was subject to deep milling and the tool was inspected and analyzed; afterwards, tool wear process and mechanism, etc. were studied. The results showed that during the deep milling of hardened steel, adhesion, oxidation, and diffusion wear appeared gradually since the stabilization of tool wear and further aggravated along with the cutting process, which led to wear and peeling of coating as well as highly possible tool damage like tipping and chipping of tool nose in later period. It was easy to generate high tool-chip interface temperature and great tool load in the high-speed deep milling of hardened steel with small corner rounding radius. In this case, the cutting edge was under considerable thermal fatigue and mechanical shock and thus subject to extensive abrasion wear, adhesion wear, and diffusion wear. The tool wear could be reduced notably by increasing the corner rounding radius.