Comprehensive optimization of process parameters in rotary ultrasonic drilling of CFRP aimed at minimizing delamination

Abstract

Delamination damage is one of the main problems in drilling of carbon fiber reinforced plastics (CFRP) laminates. In recent years, rotary ultrasonic drilling, a brand new machining process that results in better machining quality, has been attracting increasing attention. An experimental investigation carried out on carbon fiber reinforced plastics laminates using diamond core drill. Diamond core drills are simultaneously drilling and grinding fiber reinforced plastics therefore improve hole quality. To this end, a proper ultrasonic system for a core drill designed and fabricated. The effects of process parameters including cutting velocity, feed rate, thickness and ultrasonic vibration on thrust force and delamination studied. Analysis of variance (ANOVA) established to examine single and multiple effects of variables on delamination and determine their contribution rate. Subsequently, Regression models in order to predict delamination through machining parameters introduced and optimized condition evaluated. The lowest delamination is observed in lower cutting velocity and feed rate by applying ultrasonic vibration on the thinner CFRP. Machining force in rotary ultrasonic drilling method compared to conventional drilling reduced. Moreover, by statistical evaluation, resulted that thickness influence on delamination is more than other variables.