Experimental investigation on drilling of high strength T800S/250F CFRP with twist and dagger drill bits

T800S/250F lamination is a new high strength carbon fibre reinforced plastic (CFRP) material, which is usually defined as difficult-to-machine material and used to manufacture the key load-bearing structural components of large commercial aircrafts. Drilling is the most frequently operation used as the final assembling process for CFRP components, while the hole defects, such as delamination and burr, always occur at the exit of hole in the CFRP laminate. In this paper, the machinability of T800S/250F was investigated in term of drilling force, burr morphology and delamination factor by using uncoated carbide twist and dagger drill bits. The experimental results indicated that high spindle speed and low feed rate favour the reduction of thrust force for both drill bits. It was also identified that the dagger drill showed good performance with smaller burr defect and lower delamination factor as compared with the twist drill.