Edge trimming of carbon fibre reinforced plastic

In recent years the use of Carbon Fibre Reinforced Plastic (CFRP) has transitioned towards mass manufacture applications, heightening the requirement to improve both the processing capability and production cost. Machining is a key process which CFRP components often undergo, in order to achieve final assembly requirements, however, it can introduce delamination, poor surface roughness and even result in component scrap. Furthermore, the rate of tool wear and subsequently cost of tooling can be high. This paper investigates the effect of cryogenic CNC machining using liquid nitrogen on tool wear and machined surface quality for edge trimming of CFRP using different cutting tool geometries. The results show that the cutting environment has a significant effect on CFRP surface roughness and delamination for both cutting tools beyond a short period of accelerated tool wear. The cryogenic environment improved the average surface roughness of samples by 28.1% independent of cutting tool geometry compared to dry machining. Improvement to delamination was only found in samples machined with the up-down compression cutting tool, which resulted in 49.9% reduction in delamination. The lack of improvement to delamination found with the multi-tooth cutting tool is likely due to increased prevalence of the chipping mode of tool wear in cryogenic cutting environment. In contrast, the abrasive wear zone of the up-down compression cutting tool exhibited higher sharpness than in dry machining and the geometry appears to be well suited for achieving improvements in surface quality and tool wear under cryogenic machining. This research indicated the high interaction between cutting tool geometry and machining environment.