Analysis and Optimization of Kerf Width in Fiber Laser Cutting of S235 Steel

Abstract

This paper is focused on the analysis and optimization of kerf width obtained in fiber laser cutting of 3mm thick S235 steel plate using oxygen as assist gas. Focus position, cutting speed and assist gas pressure were considered as important input parameters, and were systematically varied at 3 levels during experimentation, in accordance with Box-Behnken experimental design. A second order non-linear mathematical model for the prediction of kerf width was developed and analyzed with respect to three selected parameters. The unknown coefficients of the mathematical model were found by the method of least squares. The conducted analysis showed dominant effects of focus position and cutting speed with positive and negative correlation with kerf width, respectively. Focus position of 1 mm, cutting speed of 3.6 m/min and assist gas pressure of 0.75 bar should be used in order to achieve the smallest value of kerf width. To determine laser cutting parameters to obtain target kerf width value of 0.4 mm, and at the same time maximize material removal rate, laser cutting optimization model was defined and solved using genetic algorithm. It is shown that the combination of fiber laser cutting parameters: focus position f=1.4mm, cutting speed v=3.6m/min and assist gas pressure p=0.89 bar ensures maximum productivity of 4320 mm3/min, while ensuring the targeted kerf width value of 0.4mm.