Machining Quality and Tool Wear While Drilling 3D Woven Carbon/Epoxy Composites Using Core Drills With Diamond Grains

Abstract

Advanced carbon fiber reinforced polymers (CFRP) are extensively used in aerospace, automotive and civil applications. Optimization of drilling parameters of these materials is an issue of great economical importance. This paper presents an experimental investigation of drilling of a 3D woven carbon/epoxy with diamond coated core drills and its wear mechanisms. Based on full factorial experimental design, the machinability range was identified. The influence of the machining parameters on the thrust forces and the machining quality was also investigated. The results show that the generated damage on the wall of the hole is uniformly distributed and is not affected by the fiber orientation. Analysis of wear mechanisms has indicated that grain removal and grain smoothing were the main mechanisms of wear of core drills with electro deposited diamond grains. These mechanisms of wear were investigated using tool mass and optical images. It was found that the manufacturing quality of the core drills has an important role on its efficiency. Core drills (electro deposited diamond grains) offer excellent wear resistance compared to twist drills during drilling of CFRP.