Performance evaluation of polymer-filled metal fused filament fabrication tooling for profile extrusion

The application of additive manufacturing (AM) for tooling in the mould and die industry brings a disruptive potential in process performance, design flexibility and product enhancements. Maturing of existing AM technologies and emerging technologies such as metal-fused filament fabrication (metal FFF) can further support the applicability of AM tooling in polymer profile extrusion. This study provides a complete characterization of metal FFF 17–4 PH stainless-steel die inserts and evaluates their applicability in a polymer extrusion process chain. The presented experimental assessment pivots on the metrological characterization of the produced inserts and the impact of the insert characteristics on the final extrudates’ product. Considering a conventionally manufactured benchmark insert, produced via subtractive methods (CNC machining and electrical discharge machining), comparable results for AM tools in terms of extrudates’ quality and process repeatability are presented. It was found that despite significant higher average surface parameters for AM insert tools (Sa = 2–9 µm vs. Sa = 0.3–0.9 µm for dies manufactured by machining), a much smaller difference was observed in the resulting quality of polymer extrudates’ product. The roughness generation effect of polymer profile extrusion based on the different dies’ internal surface roughness topography and the effect on extrudates product was evaluated. Three-dimensional average roughness Sa on acrylonitrile butadiene styrene extrudate surfaces obtained from conventionally machined dies was in the range of 0.3 µm. For extrudates obtained from additively manufactured dies, their Sa was in the rage of 0.5 µm (despite the much higher surface roughness of FFF dies compared to machined dies). The results confirm that with suitable extrudates’ product requirement, it is feasible to apply metal FFF as the selected manufacturing method for tooling in polymer profile extrusion.