Influence of cutting edge radius on process forces in orthogonal machining of carbon fibre reinforced plastics (CFRP)

Carbon fibre reinforced plastics (CFRP) are commonly used in the aerospace and automotive industries to reduce the mass of parts and assemblies with the goal of improving energy efficiency. When machining with geometrically defined cutting edge, the cutting edge radius of the tool is a quality-determining feature and should be kept as low as possible to enable precise separation of the fibres. It is raised by the use of coatings and by cutting edge wear. The aim of this paper is to evaluate the influence of the cutting edge radius on thrust force and cutting force when machining CFRP using an orthogonal cut. It is intended to map the drilling process by means of an orthogonal cut at certain fibre cutting angles. A new method of orthogonal machining has been developed for this purpose that considers the fibre preload and the feed movement of a drill. The fibre orientation was varied in the tool cutting edge plane. The application of small depths of cut in combination with different cutting edge radii enable the investigation of the effect of different cutting edge regions on the process forces. For this purpose, a new method for cutting edge preparation is proposed, based on the abrasive waterjet. Accordingly, the paper increases the understanding of the process when machining with high cutting edge radius.