An analysis of repeatability of laser percussion drilling process

An analysis on the repeatability of a laser percussion drilling process is conducted using a flash lamp pumped optical fibre delivered Nd:YAG laser to drill mild steel sheets. The use of percussion drilling in the industry is growing and has continually attracted new interests to the industry in recent years. However, percussion drilling is inherently inaccurate and the process is less repeatable compared to trepanning. If laser percussion drilling can achieve comparable repeatability to other processing methods, then it is envisioned that percussion drilling will be the preferred technique and that it is likely to replace many other non-lasers related techniques. In this work, the factors that influence the repeatability of the process are identified. The results would assist the industry to optimise process parameters to achieve better repeatability. The work has shown that the Percentage Standard Deviation (PSD) of entrance hole diameter was 3.5 % and 6.7 % for variation in peak power of 2 kW and 7 kW respectively. The PSD of entrance hole diameter for variation in pulse width of 1 ms and 6 ms was found to be 1.2 % and 5.2 % respectively.