A study on the drilling of composite and titanium stacks

An experimental study on drilling of graphite/bismaleimide (Gr/Bi) titanium (Ti) stacks was conducted by using different cutter materials with a standard geometry to understand and characterize the process. The tool materials used were high-speed steel (HSS), high-speed cobalt (HSS-Co), and carbide. It was observed that at the interface of Gr/Bi-Ti, high temperatures induced material damage near and around the hole region. Dissimilar mechanical and thermal properties affected the tool life and allowed for increased matrix degradation and burr formation in Ti, regardless of the cutting tool material. As a result, fewer holes were produced when high spindle speeds and slow feeds were used. It was also found that carbide drills outperformed all other tools in terms of tool life, minimal surface damage, and heat induced damage on both workpiece materials. (C) 2001 Elsevier Science Ltd. All rights reserved.