Study of damage in CFRP and GFRP composite in drilling

The laminate composite plates are a candidate to delaminate when subjected to stresses concentration during the drilling operation. In this paper, the influence of drill feed rate and diameter in the delamination of composite plates is studied by experimental tests. For this purpose a carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP) plates with different thickness are made in laboratory and drilling is done for the 54 different drilling condition cases. Based on digital images processing (DIP) for the drilled surfaces, an image of the damaged area was used to measure the delaminated area and then compare the results. Optimum feed rate is obtained as 200 mm/min for CFRP and 125 mm/min for GFRP with the spindle speed of 800 rpm. By increasing the thickness of the composites, there is a decrease in the delamination, so that by increasing the thickness of the CFRP and the GFRP to 4 mm, with increasing diameter of the drilling tool, the area of the damage region in the same feed rate has decreased. In most cases, a directly proportional relationship was confirmed between an area of damage region and the feed rate.