Mechanism of material removal during orthogonal cutting of graphite/polymer composites

Abstract

With the engineering applications of graphite and its composites increasing, machining of graphite and its composites has attracted a great deal of attention. However, the cutting mechanisms of graphite and its composites are different from metals and other brittle materials because of specific crack initiation and propagation laws. This paper establishes a finite element model to calculate the effective stress field of the cutting zone during the orthogonal cutting of graphite/polymer composites. The crack initiation and propagation path in the cutting zone is determined by the smallest effective stress gradient at different cutting thicknesses and verified by edge-indentation experiments. Based on the crack initiation and propagation laws, a model of the graphite/polymer composites cutting process is proposed to understand the mechanism of material removal as well as machined surface formation. The cutting process of graphite/polymer composites can be divided into three stages: removal of large blocks, tiny blocks, and small blocks of graphite, which results in large, tiny, and small concavities, respectively, remaining on the machined surface. The cutting model is validated through machined surface morphology, cutting force, and chip morphology.