Investigations into the effect of geometry of a trepanning tool on thrust and torque during drilling of GFRP composites

This paper presents the results of an experimental investigation into the e ffect of the geometry of a trepanning tool on thrust and torque during the drilling of uni-directional glass fibre-reinforced plastic (UD-GFRP) lamina tes. It is well-known that the most effective way of achieving good quality holes while drilling fibre-reinforced plastics (FRPs) is by reducing the t hrust and torque. Therefore, this investigation was aimed at exploring the possibility of reducing the thrust and torque by using the concept of trepa nning. The design considerations and development methodology of the trepann ing tool are discussed. The appropriate tool geometry has been determined b y using statistically planned experiments and analysis. Orthogonal arrays w ith analysis of means as well as analysis of variance have been used to ass ess individual factor and interaction effects and their significance levels . The investigations have revealed that the performance of the trepanning t ool is superior to that of conventional twist drills in terms of thrust, to rque and hole quality. Low production cost and ease of regrinding are its m ajor additional advantages due to its simple geometry. (C) 1999 Elsevier Sc ience S.A. All rights reserved.