Effect of process parameters on the weld quality of 3D printed PLA-CF sheets by FSW process

Friction stir welding (FSW) process is commonly used in the joining of similar/dissimilar materials. FSW involves process parameters that can affect the weld quality. To enhance this, it is important to accurately determine the process parameters. In this study, the weldability of 3D printed carbon fiber-reinforced polylactic acid (PLA-CF) sheets has been investigated using FSW. The process was carried out with three different tool pin geometries (triangle, square, and screw), feed rates (20, 40, and 60 mm/min) and tool rotational speeds (1250, 1750, and 2250 rpm). Tensile tests were conducted and hardness measurements were taken to discuss the effects of process parameters on weld quality. Temperature values were measured to examine the impact of tool pin geometry on the heat generation during welding. Finally, visual and microstructure examinations were conducted in the weld zone to assess the changes in weld strength. As a result, it has been determined that weld strength is significantly influenced by the process parameters. Accordingly, the best weld quality was achieved with triangular pin profile at a traverse speed of 40 mm/min and a rotation speed of 1250 rpm (UTS: 43.6 MPa, efficiency 79.6%), while for square pin (UTS: 49.2 MPa, efficiency 89.8%) and screw pin (UTS: 44.9 MPa, efficiency 81.9%) geometries, the optimal values are 20 mm/min and 2250 rpm. The distribution of CF reinforcement is uniform in high weld strength samples, while with lower weld quality samples, the distribution is irregular. This indicates that the reinforcement of CF has significant effect on weld strength.Highlights Investigate the weldability of 3D printed PLA-CF plates through FSW process. Examines the impact of pin geometry, feed rates, and tool rotational speeds. Determine the welding strength and temperature generated during welding. Choice of the square pin geometry is more suitable for joining PLA-CF plates. Visual and microstructure examinations were conducted in the weld zone.