On the interpretation of drilling CFRP/Ti6Al4V stacks using the orthogonal cutting method: Chip removal mode and subsurface damage formation

The present paper aims to utilize the orthogonal cutting method to offer an enhanced interpretation of the drilling process on CFRP/Ti6Al4V stacks. It contributes to relating the chip separation modes of the orthogonal cutting of multilayer CFRP/Ti6Al4V stacks with their drilling characteristics. A particular focus was made to identify the effect of different cutting sequence strategies on the 3D topographies and defects formation of cut CFRP/Ti6Al4V stacks as well as the mechanisms controlling the drilling of the stack interface. Three configurations of orthogonal cutting operations considering both the impact of varying cutting sequence strategies and the combined interface machining were implemented and the in-situ chip removal characteristics were documented. Mechanical drilling of CFRP/Ti6Al4V stacks was performed subjected to varying cutting sequences and process parameters. Aspects involving the cutting forces, drilling-induced damage as well as the machined hole morphologies were carefully addressed with respect to the used cutting conditions. The obtained orthogonal cutting results were utilized to facilitate the stack drilling comprehension. The results discussed in this paper highlight the vital role of the cutting sequence strategy in the stack machinability and permit an enhanced interpretation of drilling this multilayer material.