Modelling and optimization of cut quality during pulsed Nd:YAG laser cutting of thin Al-alloy sheet for curved profile

Abstract

CO2 Lasers in general, and Nd:YAG lasers in particular, are widely used for cutting of reflective sheetmetals to obtain the exceptional good quality cut. Due to shorter wavelength of Nd:YAG laser, it is reflected by lesser extent from the metallic surfaces. This paper presents the modelling and optimization of cut quality characteristics during Nd:YAG laser cutting of aluminum alloy thin sheet along the curved profile. The cut quality characteristics considered are average kerf deviation (Da) and average kerf taper (Ta). The essential input process parameters are identified as arc radius of curve profile, oxygen pressure, pulse width, pulse frequency and cutting speed. First, second order response surface model was developed for each Da and Ta using hybrid approach of Taguchi methodology (TM) and response surface methodology (RSM). The effect of input process parameters on each cut quality (Da and Ta) was also studied. Second, preferred operating laser cutting parameters were obtained using grey relational analysis (GRA) with entropy measurement (EM) to minimize Da and Ta together. In the present study a L27 orthogonal array (OA) is used for experimentation. The entropy measurement (EM) method is employed for the calculation of weights corresponding to each quality characteristic Da and Ta. Finally, significant improvement in Ta has been observed from the verification results.