How can we minimize damage when drilling composites? This study investigates the chisel edge and pilot hole effects in drilling composite laminates to reduce delamination, a common issue arising from the material's poor strength in the thickness direction. The research reveals that the chisel edge is a major contributor to the thrust force causing delamination. A series of drilling experiments on carbon fiber-reinforced composite laminates quantified the effect of the chisel edge on thrust force. Tests with pilot holes showed a large reduction in thrust, effectively removing the chisel edge contribution. An analytical model incorporating the pilot hole presence was also developed. The results from the thrust force-feed relationships demonstrate a good agreement with experimental values. Pilot holes can greatly improve drilling of composite laminates. Further research might focus on drill bit designs that minimize thrust force, reducing delamination.
This article, published in the Journal of Manufacturing Science and Engineering, aligns with the journal's emphasis on advancing manufacturing processes. By analyzing the mechanics of drilling composite laminates and proposing methods to reduce delamination, the study contributes to the journal's focus on improving manufacturing efficiency and quality.