Laser hole drilling of composites and steel workpieces

Laser drilling of steel, carbon-carbon plain weave and Kevlar laminates are investigated. The thermal efficiency and specific energy requirement for the drilling process is considered. A lump parameter technique is employed to formulate the thermal efficiency and specific energy requirement of drilling. The study is extended to include the experimental investigation of the drilling process. The hole quality, based on the inlet and exit features of the hole, is assessed and compared with traditionally drilled holes in Kevlar laminates. It is found that the thermal efficiency is high for steel followed by carbon-carbon plain weave and Kevlar laminates. The specific energy required is highest for carbon-carbon plain weave laminates. This is mainly due to the high melting temperature of the substrate material. Laser drilled holes and have better inlet and outlet hole quality than conventionally drilled holes and show no delamination and loose fibres at the inlet and outlet holes.