Two-step optimization of hybrid friction stir welding parameters for MEX 3D printed ABS-ASA joints

The production of polymeric welds remains a challenging task. This study aimed to investigate the feasibility and performance of joining two popular thermoplastics, acrylonitrile styrene acrylate (ASA) and acrylonitrile butadiene styrene (ABS), with differing compositions and thermal behaviors, produced via additive manufacturing, which adds an additional challenge to the process. In the first optimization stage, a Taguchi L9 analysis for screening was performed, while the second utilized a Full Factorial design. The response metrics were the tensile and flexural strengths and stiffness, forces along the three axes, welding temperature, and friction index. The initial phase involved four control parameters: travel (TS) and rotation (Rs) speeds, and the shoulder and pin diameter of the welding tool (nine experimental runs). In the second phase, the optimal welding tool was employed, and Ts and Rs were tested (six experimental runs). The most notable performance was observed with a 3 mm/min Ts, 1800 rpm Rs, and a welding tool with a 10 mm/4 mm diameter geometry. The regression models assessed included the Linear Regression Model and the Reduced Quadratic Regression Model, achieving R2 values higher than 99 %. A welding efficiency (ratio of the welded and unwelded parts tensile strength) of greater than 100 % was achieved. The welding conditions sensitivity was revealed as more than 200 % improvement in the mechanical properties was reported (33MPa/14 MPa tensile, and 76.1MPa/37.6 MPa flexural strength, respectively). These findings provide valuable insights for scientific and industrial communities by offering intriguing and applicable information for future applications in challenging environments.