Use of “assist” gas in the laser drilling of titanium

A series of experiments is reported which investigate the effect of an “assist” gas on the single-pulse Nd:YAG laser drilling of titanium. Hole breakthrough percentages are determined for arrays of holes drilled without an assist gas and with assist gasses of different pressures and compositions. Breakthrough percentages are given as functions of laser pulse energy for various thicknesses of material under different assist gas conditions. Regimes are identified in which the use of a gas assists drilling and others in which it hinders drilling—mechanisms for these effects are proposed. The effect of the reactivity of the assist gas on hole dimensions is also reported.