Optimization of hybrid friction stir welding of PMMA: 3D-printed parts and conventional sheets welding efficiency in single- and two-axis welding traces

Herein, the feasibility of joining with the friction stir welding (FSW) process 3D-printed parts made of poly(methyl methacrylate) (PMMA) with extruded PMMA sheets is investigated. A full factorial design method is followed, with two control parameters, i.e., tool rotational and travel speed, and three levels each. The hybrid joints produced were subjected to tensile and flexural loading and the corresponding properties were optimized with statistical modeling tools. Regression analysis provided prediction models for the five output metrics. The temperature was monitored throughout the experimental process. Samples were inspected with optical and scanning electron microscopy and their morphological characteristics were correlated with the joining conditions. The optimized FSW parameters were used for joining PMMA 3D-printed parts with sheets with two-axis joining seams. The produced hybrid joints were more than sufficient in their mechanical properties. The highest welding efficiency achieved in the tensile tests was 1.36, by the sample welded with 900 rpm and 6 mm/min. The sample welded with the same conditions achieved also the highest welding efficiency in the flexural tests (0.98). The findings presented proven the efficiency of the hybrid PMMA joints studied and have direct industrial applications for efficient component production.