Investigation of Chip Formation Characteristics in Orthogonal Cutting of Graphite

Graphite becomes the prevailing electrode material in electron discharge machining (EDM) currently. This article aims to reveal the chip formation characteristics of graphite by orthogonal cutting experiments. The results showed that semicontinuous chip, crushed particle chip, and fractured block chip formation were identified as three major types of graphite chip formation. The transitions of chip formations were highly dependent on the depth of cut. The chips produced in different type of chip formation exhibited different surface fractography. Three types of chip size distribution corresponded well to three types of chip formation. The surface roughness and cutting force increased prominently with the depth of cut increasing. The cutting force response in each type of chip formation can be identified by the fluctuation extent and waveform of cutting force.