Flank wear studies on alumina tools in steel cutting

The mechanisms/processes in the evolution of flank wear patterns of alumina ceramic tools in the machining of annealed and hardened steels (AISI 1045 and 4340) were investigated microscopically. A new flank wear model separating the athermal (mechanical) and thermal (chemical) wear aspects was presented. A framework for a mechanical wear model was proposed in terms of work hardness, fractal description of tool surface, and fracture energy. Additionally the fundamental behavior of chemical wear was investigated in terms of work chemistry, oxidation of steels, and tool-work interfacial interaction.;The flank wear on alumina tools increased with increasing cutting speed and distance on both annealed AISI 1045 and 4340, which have the same hardness. However, both chemical and mechanical wear mechanisms were found to be active to a different degree with workpiece/alumina tool pairs. There is a critical cutting speed above which chemical wear was observed (83 m/min). From the heating experiments, it was found that the large difference in wear amount along the workpieces at higher speeds (;A wear model has been developed and experimentally verified which provides a separation of mechanical and chemical wear aspects both qualitatively and quantitatively. A further model is proposed based on the concept of equivalent cutting energy per unit cutting distance at various cutting speeds within which the wear model plays a part. This concept along with the proposed fractal description would be useful in classifying the mechanical fracture modes with cutting speed and work hardness. The flank wear curves of alumina tool on annealed and hardened steels may serve as guidelines for selecting the optimum speed condition of machining.