Cryogenic Machining of Carbon Fibre

Processing of composite structures can consist of drilling of holes for joining and assembling of different components. Drilling of composites presents a number of challenges, namely, delamination, excessive burr formation, fibre splitting, heat affected zones and significantly reduced tool life. This paper explores the use of cryogenic CNC machining methods for machining of holes in carbon fibre, typically used in aerospace. Test parts are drilled using a range of different machining parameters, standard carbide tooling and different machining conditions, namely, dry, and cryogenic using liquid nitrogen. The results show that cryogenic methods reduce the amount of delamination and surface roughness, particularly at elevated machining parameters. Cryogenic CNC machining provides a realistic method for drilling of carbon fibre composites that reduces delamination and surface roughness.