Additive manufacturing in polymer extrusion tooling: experimental testing and surface characterization

The die design process in polymer extrusion requires multiple iterations to enable the mass production of complex cross-sectional products. Polymer-based additive manufacturing (AM) or soft tooling offers an economical solution for small batches and highly customized items. However, soft tooling faces limitations due to the degradation of polymer material properties under continuous exposure to high temperatures and pressure. This study explores the experimental capabilities of additively manufactured Carbon Fibre (CF) Polyether-Ether-Ketone (PEEK) dies using the Fused Filament Fabrication (FFF) process. The experimental testing involved a single screw extruder and wet calibration setup with three different screw speed levels. Acrylonitrile butadiene styrene (ABS) and Polypropylene (PP) were used as the extruded materials. The die profile has restrictions and variable thickness, which is subjective to imbalanced melt flow. The results indicate that CF-PEEK AM die withstood the demanding process conditions of polymer extrusion. However, challenges were encountered during the experimental testing, including leaking in the die adapter and lower screw speed setting due to imbalanced melt flow. The study analyzed the surface topography of the extrudates using a 3D confocal microscope. The surface roughness parameters of PP and ABS are measured by the arithmetical mean height (Sa) with an average and standard deviation of 2.0±0.4 μm and 2.1±0.6 μm, respectively.