Abstract
Abstract
The effects of intra- and interpulse temporal modulation (shaping) during laser percussion drilling are investigated in terms of hole geometry characteristics and control. While intrapulse shaping involves temporally shaping within an individual laser pulse and repeatedly using the shaped pulse throughout the pulse train, interpulse shaping is carried out by temporal pulse shaping the overall delivery pattern of a pulse train required to percussion drill a hole. A fibre optic delivered neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was employed to drill through-holes in stainless steel 304 plates with various combinations of intra- and interpulse shapes. The fundamental effects of intra- and interpulse shaping are also compared with percussion drilling using unshaped rectangular intrapulses and the normal delivery pattern interpulse shape. The work has shown that interpulse shaping is effective in reducing the hole taper and improving the overall hole wall parallelism during laser percussion drilling. This was chiefly attributed to the optimized laser pulse distribution as the beam propagates into the hole.