Experimental Study on Drilling of GFRP and CFRP Composites

Abstract

Glass fiber reinforced plastic (GFRP) and Carbon fiber reinforced plastic (CFRP) are widely used composites in the area of manufacturing industry. Drilling of such composites for assembling is increasing fast with the increase in demand for such composites materials. The high specific strength and fatigue characteristics of such composites make these superior as compared to conventional material. Several damages like uncut fibers, delamination, edge chipping fiber pull out, and occur during drilling. Delamination is the major problem during drilling of CFRP and GFRP as it causes poor assembly tolerance, reduced structural integrity and deteriorated long term performance. Machining of composites is performed at various drilling parameters using CNC machine. In order to reduce number of experimental runs, a face centred central composite design (FCCCD) is used considering feed rate, spindle speed, and drill size as three drilling parameters. Delamination factor of CFRP and GFRP under each experimental run is estimated. It has been observed that delamination is related to the thrust force. The thrust force of step drill and through hole drill under different drilling parameter setting during drilling of CFRP and GFRP is experimentally obtained using drill dynamometer. It has been found that step drilling is superior to through hole drilling since it reduces thrust force and consequently delamination.