Influence of Point Angle on Drill Hole Quality and Machining Forces when Drilling CFRP

This paper presents the results of investigations concerning the influence of the point angle of a drill tool and increased cutting speeds on machining forces and drill hole quality (delamination, fraying, burr formation). Elevated point angles result in increased feed force F-f while the drilling torque T-d stays almost constant. The assessment of characteristics concerning drill holes show that the quality at the entrance is best when using point angles > 180 degrees, while it is poor at the exit. The increase in cutting speed leads to almost no differences in drill hole quality but does lead to rising feed forces and decreasing drilling torques. (C) 2012 The Authors. Published by Elsevier B. V. Selection and/or peer-review under responsibility of Professor Konrad Wegener