Manufacturing motor core lamination from thin non-oriented silicon steel sheet direct by pulsed laser cutting using multi-quality optimized process parameters

Based on the experimental results, this study develops a multi-objective optimization scheme to obtain the set of optimal process parameters for pulsed laser direct cutting of non-oriented silicon steel sheets for manufacturing motor core laminations. The experiments were conducted in the nital solvent, which was the one with the smallest thermal effect of laser cutting among the candidate environments of air, deionized water, alcohol, lubricant oil, sodium chloride solution, and nital solution. The laser was a pulsed Nd:YAG nanosecond laser and the thickness of the silicon steel was 100 μm. The effects of three laser process parameters, laser power (P), cutting speed (v), and pulse repetition rate (f) on the cutting qualities of the heat-affected zone (HAZ), cutting time (T_C), and multiple dimensional accuracies of the cut core lamination were examined. The inspected geometric accuracies included the errors in inner and outer core diameters (E_D1 and E_D2), the error in tooth width (E_L), and the roundness of inner and outer diameters (C₁ and C₂). The developed multi-objective optimization model was a PSI-based ELM-GA scheme consisting of the extreme learning machine (ELM) model for connecting the inputs and the outputs, the preference selection index (PSI) method for obtaining the weighted multi-objective function, and the genetic algorithm (GA) for process optimization. Through employing the predicted optimal process parameter set, the validation experiment showed that the errors between the prediction and the experimental result for the seven qualities of HAZ, E_D1, E_D2, C₁, C₂, E_L, and T_C were 4.04%, 6.25%, 4.02%, 0.48%, 2.14%, 5.09%, and 1.25%, respectively. The HAZ and geometric accuracy of the cut core laminations were qualified for the subsequent lamination assembly. Consequently, the merit of direct formation of ready-for-assembly core laminations without the need for any post-processing renders the proposed laser cutting scheme an economical and effective approach for manufacturing motor core laminations from thin silicon steel sheets.