Experimental testing and characterization of additively manufactured CF-PEEK dies for complex profile in polymer profile extrusion

Polymer extrusion has the ability of mass-products with complex cross-sections. However, final die geometries and profiles are achieved after several die design changes and iterations which result in high development costs to manufacture new dies. The integration of polymer additive manufacturing (AM) in the extrusion production value chain has the potential to enable polymer extrusion for small batches and highly customized products. The present work investigates the experimental capability of additively manufactured Carbon Fibre (CF) Polyether-Ether-Ketone (PEEK) dies produced by the Fused Filament Fabrication (FFF) process. The challenge of polymeric dies or soft tooling is represented by their limitations with respect to the demanding process conditions of polymer extrusion. The experimental testing in this work was performed on a single screw extruder and wet calibration setup using four different screw speed levels. The cross section of the die profiles has circular features including non-uniform wall thickness. The extruded materials are Acrylonitrile butadiene styrene (ABS) and Polypropylene (PP). The study characterized the dimensional and surface topography of the produced extrudates by means of a micrometre and a 3D confocal microscope, respectively. The result indicates that CF-PEEK AM dies can withstand the demanding process conditions of polymer extrusion, maintaining the desired cross section within product specifications and surface roughness parameters of arithmetical mean height (Sa) with average and standard deviation of 2.3±0.8 μm for PP and 2.7±1.1 μm for ABS.