Influence of machining parameters on the wear mechanisms of PCD tools during turning of tungsten carbide

Abstract

Tungsten carbide (WC) exhibits high hot hardness and excellent abrasion resistance, making it widely employed in mold manufacturing, aerospace, and precision component production. However, its extreme hardness leads to severe tool wear during cutting, which limits both machining efficiency and surface quality. Therefore, understanding the mechanisms of cutting tool wear and their evolution during tungsten carbide turning is critical for improving machining accuracy and tool life. In this study, dry orthogonal turning experiments were conducted on WC-15Co using a polycrystalline diamond (PCD) tool to investigate the effects of machining parameters and material removal volume on tool wear from a thermo-mechanical coupling perspective. The results revealed that cutting temperature was more sensitive to cutting speed than to feed. Cutting forces were influenced by both material thermal softening and tool wear, resulting in a decreasing trend in the tangential force with increasing cutting speed, while the feed force initially decreased and subsequently increased. At low material removal volumes, the pronounced thermal softening combined with minimal initial tool wear yielded optimal surface quality at a cutting speed of 250 m/min. However, in terms of tool life, a cutting speed of 100 m/min provided a better thermo-mechanical balance, resulting in minimal wear and stable surface quality. Under high-speed cutting conditions (≥350 m/min), chips transformed from discontinuous to continuous due to thermal softening and the extrusion effect induced by tool wear, which adversely affected surface quality. The wear behavior of PCD tools was strongly dependent on cutting speed: at lower speeds, adhesion and abrasive wear were dominant, whereas at higher speeds, rapid tool failure occurred due to diamond graphitization, severe oxidation, and spalling of large adhered layers. This study elucidates the mechanisms by which thermo-mechanical interactions influence tool wear under varying machining parameters, providing theoretical insights and guidance for parameter optimization to achieve efficient and stable turning of tungsten carbide, with significant engineering implications.