Multi-performance optimization of small-scale resistance spot welding process parameters for joining of Ti-1Al-1Mn thin foils using hybrid approach

The progressive trends of product miniaturization and light-weighting necessitate the effective microjoining of ultra-thin metal foils with high reliability and performance. In this experimental investigation, Ti-1Al-1Mn foils of 0.05 mm thickness were welded by small-scale resistance spot welding (SSRSW). The experiments based on Taguchi L27 orthogonal array have been implemented to examine the effects, significances and optimal combination of welding parameters, namely welding current, electrode force, ramping time and welding time. Performance measures viz., tensile-shear force, peel force, variances of tensile-shear and peel force were optimized by a hybrid approach comprising gray relational analysis (GRA) with principal component analysis (PCA). Furthermore, two kinds of weighted gray relational grade which extracted different numbers of principal components were put into comparison for better comprehensive performance by analysis of variance (ANOVA) and confirmation tests. It indicated that the procedure of parameter optimization should only extract all the principal components that correspond to eigenvalues larger than one. The ANOVA results showed that welding current was the most significant impact on multi-performance, followed by electrode force and ramp time, while welding time showed little effect. Finally, the optimal welding parameters combination was at welding current of 800 A, electrode force of 35.6 N, ramp time of 5 ms, and welding time of 8 ms.