Experimental characterization and evaluation of additively manufactured PEEK dies for polymer profile extrusion

The challenge in prototyping of new extrusion profiles is the high development cost to develop and manufacture the corresponding extrusion dies. Thus, tooling process chains based on polymer additive manufacturing (AM) are of industrial interest to manufacture functional dies capable to produce a small batch of prototype extruded profile. The work presented here concerns the production and testing of a series of carbon fibre reinforced polyether-ether-ketone (PEEK) dies in polymer profile extrusion. The die geometry has been optimized by adopting a conical design to improve the die flow and the melt flow distribution. Therefore, the material selection and improved geometry design are implemented to withstand the combination of high temperature and pressure typical of the extrusion process. The dimensional and form measurement using a tactile coordinate measuring machine (CMM) was performed before experimental testing to investigate the accuracy and reproducibility of dies manufactured by the fused filament fabrication (FFF) process. From the measurement of 15 samples, the accuracy of dimensional measurement was identified by the absolute deviation between 39 μm and 435 μm depending on reference dimension. Relative standard deviation to the reference dimension of 0.2% and 2.35% indicates the reproducibility of FFF process. Furthermore, surface characterization of internal die was performed using replica technology in a focus variation 3D optical microscope. The surface roughness was evaluated using an average arithmetical mean height (Sa) value of 17.3 μm with standard deviation of ±1.9 μm. PEEK die was experimentally tested with Polypropylene (PP) as material extruded. As the result, PEEK die was able to withstand the extrusion process conditions, yielding up to 330 meters of extruded product.