Nd:YAG laser drilling of slate

We have undertaken a series of experiments to investigate the feasibility of using a Nd:YAG laser to drill slate tiles. Slate is primarily used as roof building material by splitting in thin flat layers. The traditional fixation system of slate tiles in Europe consists in clamping the slate pieces by means of metallic clamps and overlapping the different tiles in order to form an impervious roof. An alternative to this clamping technique, is the use of nails to fix the slate tiles to a wooden frame. This method improves the fixation of the slate tiles and reduces the costs related to roof repair, extending the period between maintenance. But, of course, the use of nails requires hole making in slate pieces, which is currently done by mechanical means, resulting in big holes and extended manufacturing time. The aim of this work is to explore the capabilities of a pulsed Nd:YAG laser to drill tiny holes in slate tiles in order to produce a better quality drilled slate tile in a reduced time. Thus, shallow holes were obtained by using a 1kW Nd:YAG pulsed laser focused by a 80 mm fused silica lens on the slate surface. The results obtained show the enormous potential of Nd:YAG laser in the treatment of slate.