A study of diamond cutting mechanism for aluminum alloy 6061 with AlFeSi particle effect: Modeling and simulation

Abstract

Aluminum alloy 6061 (Al6061) contains two main intermetallic compounds: Mg2Si phase and AlFeSi particles. The hard-brittle particles generate protrude, voids and scratch marks on the machined surface which can not be ignored for the nanometric surface quality in ultra-precision machining. This paper makes a further study on the formation mechanisms of three surface defects induced by AlFeSi particle which is bigger in size and more in amount than Mg2Si on Al6061. The cutting mechanism, including stress distribution, deformations, surface morphology and chip formation is compared between conventional Al6061 with micro-particles and RSA6061 with submicro-particles by conducting diamond orthogonal cutting experiments and developing finite models. It is found that the type of surface defects is related to the particle size and locations. Better machined surface quality with fewer defects can be obtained from RSA6061 with submicron particle compared with Al6061, and better agreement is found between the simulation results from FE model with AlFeSi particles effect and experiment. Based on the cutting mechanism study, surface roughness prediction model is developed for two Al6061 alloys in SPDT by considering the AlFeSi particle effects on minimum chip thickness (MCT) and the tool-workpiece contact conditions as well as particle-induced roughness components. Diamond turning experiments are conducted to verify the proposed prediction model and shows that, the new model makes a more precise prediction for conventional Al6061.