Experimental analysis of special tool geometries when drilling woven and multidirectional CFRPs

Abstract

Drilling is one of the most frequent machining operations for carbon fiber-reinforced polymer composites, carried out prior to assembly between structural components using mechanical joining. Delamination is the main damage mechanism involved during carbon fiber-reinforced polymer composite drilling causing an elevated percentage of workpiece rejection. Tool geometry strongly influences drilling performance. In this paper, an original work dealing with the comparison between three recently developed configurations (Brad center, Step drill and Reamer drills) in terms of drilling forces and delamination both for woven and tape carbon fiber-reinforced polymers is presented. Reamer drill showed the best results concerning productivity and delamination. Strong differences were found when hole quality obtained in tape and woven composite was compared: multidirectional composite presented poorer hole quality than woven composite under the same cutting conditions. The analysis of variance was developed in order to analyze the influence of each parameter showing the importance of feed rate on surface damage.