Cutting of AA6061 by a multimode pulsed Nd:YAG laser with high pressure gas: characterisation of kerf geometry and quality

In this work, laser cutting of 6061-T6 aluminium alloy sheets is investigated using a multimode 150 W Nd:YAG pulsed laser, adopting N2 at 15 bar, with the aim to investigate the effect of process parameters on the kerf geometry and roughness. The study was divided in two steps: first, in order to determine the domain where a throughout cut is possible, cutting tests were performed at a fixed average power (150 W), changing the pulse duration and the cutting speed. Then, in order to assess the influence of the process parameters on kerf geometry and roughness, a second set of tests was carried out, at the same average power and pressure, changing the pulse duration, the scan speed and the beam travel direction. The tests were performed adopting a full factorial design 32 × 2 according to the DoE methodology. Analysis of variance (ANOVA) was used in order to determine which of the process parameters affects the kerf characteristic and how. Response surface method (RSM) and multiresponse optimisation (MRO) were adopted to optimise the process conditions. The various effects of the process parameters on the kerf geometry and quality have been analysed and discussed. Finally, it was found that the MRO is able to select a parameter set able to minimise the effects of the multimode energy distribution beam.