Experimental investigation of simple foam-stacked in drilling process for carbon fiber reinforced plastic

Carbon fiber reinforced plastics (CFRPs) have a variety of uses in aerospace and automobile industries for their outstanding mechanical properties. Although the defects occur during machining CFRP, drilling CFRP is necessary to assemble individual parts. Delamination is a major defect that degrades the strength of structures; it must be avoided when drilling CFRP. In this study, a new approach was proposed to reduce delamination defects using foam when drilling CFRP laminates. Three different types of foams were used to support CFRP laminate during drilling process. The thrust force and extent of tool wear on the cutting-edge of the drill bit were measured and analyzed. The thrust force decreased during foam-stacked CFRP drilling, but there was no significant difference in tool wear. The delamination factors acquired from the exit morphologies of the drilled holes of the CFRP by comparing them with and without foam as a back-up plate. The delamination factor increased as the number of holes drilled in the CFRP increased. The delamination factor decreased to 35.9% with the use of extruded polystyrene foam as a back-up plate, based only on drilling CFRP; hence, the delamination damage when drilling CFRP can be effectively reduced by supporting foam.