Investigation of the effect of drilling parameters on mechanical properties in drilling of fiber reinforced composites

Fiber reinforced plastic composite materials are widely used in aircraft, space, automotive and other engineering fields due to their good mechanical properties. Deformations occur due to drilling parameters and mechanical properties in the drilling of these materials. Due to these deformations, 60% of the composite parts cannot be used in the aircraft industry. In this study, the drilling performance of carbon fiber reinforced plastic (CFRP) composites that have different fiber orientation angles were investigated at different drilling parameters. The experiments were performed at spindle speeds of 1000, 3000 and 5000 rev/min and feed rates of 0.05, 0.10 and 0.15 mm/rev by using drills having different geometries and materials. Cutting force, surface roughness and deformation were evaluated as drilling performance. The tensile forces of the CFRP composites were determined after drilling CFRP composites and calculating delamination factors. Than the effect of the delamination factor on the tensile strength was investigated. Fatigue tests of samples with at minimum, mean and maximum delamination factors were performed. Fatigue tests were carried out at 75%, 80%, 85% and 90% load ratios based on the lowest tensile force of the drilled samples. It has been determined that the cutting force increased and delamination factor and surface roughness decreased with increasing the spindle speed. The cutting force, delamination factor and surface roughness increased with increasing the feed rate. The best drilling performance was obtained from WC drills due to the high hardness and abrasion resistance in all experiments. It was determined that the tensile force and fatigue life of CFRP composites having low surface roughness and delamination factor were high.