Wear characteristics of polycrystalline diamond tools in orthogonal cutting of CFRP/Ti stacks

CFRP/Ti stacks have become a viable alternative to conventional composite laminates and metal alloys in various aerospace applications because of their enhanced mechanical properties and improved structural functions. Machining these multilayer stacks with acceptable quality still remains a great challenge for the modern manufacturing sectors due to the ineffective management of the tool wear performance resulting from the varying properties of the stacked constituents. This paper describes, on a fundamental basis, the wear characteristics of polycrystalline diamond (PCD) tipped tools during the orthogonal cutting of CFRP/Ti stacks. Two cutting sequence strategies, i.e., cutting from CFRP to Ti and cutting from Ti to CFRP, were implemented throughout the cutting tests. The experimental results confirm the predominance of the cutting sequence strategy in affecting the CFRP/Ti chip separation and the machined surface quality. The chip adhesion is a most influential factor leading to the disparate influences of the two cutting sequence strategies on the CFRP/Ti cutting responses. The PCD tool suffers severe crater wear due to the Ti phase cutting, while it undergoes minor flank wear owing to its superior wear resistance against abrasive carbon fibers. The wear signatures on the tool-chip contact zone via the scanning electron microscope (SEM) observation reveal that the Ti phase cutting dominates the formation of the tool crater wear land. The edge chipping occurs mainly due to the sudden force variation in the CFRP/Ti interface machining and the inherent brittleness of the PCD material. The fiber orientation seems to have a great impact on the wear behavior of utilized PCD tools by altering the tool-chip contact length.