Performance evaluation of carbide tools in drilling CFRP-Al stacks

Abstract

Composite-metal stack is an ideal combination of materials which unites the advantages of each dissimilar material in a substantial weight. However, drilling dissimilar materials has been a challenge since the composite-metal stacks are at demand in industries. It is important to choose the appropriate drill geometry regarding the stacking sequence and utilize proper machining parameters in order to achieve damage free and precession holes. This experimental study was conducted on dry drilling of CFRP/Al2024/CFRP (carbon fiber-reinforced plastic). Four types of twist drills with various geometries, both coated and uncoated, were utilized to study the effect of machining parameters on hole quality. It was observed that increasing feed rate entails an increase in entrance delamination, whereas exit delaminations and fiber fraying at 2nd CFRP exit diminished with increasing feed rate. It was also found that four facet tools performed better than two facet tools in terms of fiber delamination. Most accurate hole was attained on 2nd CFRP; however, it was found that increasing feed significantly affects the hole size on 1st CFRP.