Machining of Carbon Fibre: Optical Surface Damage Characterisation and Tool Wear Study

Better control of fibre composites machining requires reliable surface roughness and damage characterisation measurements. The performance and tool wear rate of three different state of the art CVD and PCD cutting tools manufactured for carbon fibre machining were compared in wet and dry conditions. Machined surfaces were characterised by areal surface roughness parameters using a novel focus variation optical system. The tool wear and cutting forces were recorded up to 50 linear meters of machining or until tool failure. Results showed that wet machining conditions reduced tool failure; and that the CVD tool in wet conditions machined the greatest distance of 26m before reaching an average roughness limit of 3μm. The tool type was found to be the most significant parameter on the surface quality. The optical system was found to be a useful tool for measuring roughness of individual plies and characterising machining induced surface damage.