Optimisation of cut qualities during pulsed Nd: YAG laser cutting of SUPERNI 718 thin sheet for straight profile

摘要

This paper reports the study of optimal process parameters for cutting Ni-based super alloy (SUPERNI 718) thin sheet along straight profile using Nd: YAG laser. The average kerf taper (T_a) and surface roughness (R_a) are considered as cut qualities and the essential process input parameters are identified as oxygen pressure, pulse width, pulse frequency and cutting speed for the present study. Taguchi methodology with L_9 orthogonal array is employed for optimising both cut qualities individually and simultaneously. The optimisation results show a considerable improvement in the both qualities and the confirmatory experimental results have shown good agreement with the predicted results. It has also been found that the optimum condition of the cutting parameters for multi-performance characteristics varies with the different combinations of weighting factors. Based on the analysis, more weight has to be set for T_a to obtain the good quality cut. Finally, the results of multiple quality optimisation have been compared with the single quality optimisation results. From the comparison it has been found that R_a was increased by 30.34% in multiple quality optimisation however the T_a was same in both cases.