[T7] AM Sinter Based Technologies

[16A-T7-22] Evaluation and Optimization of Process Stability for Piston-based Material Extrusion with MIM Feedstock

*L. Hermans¹, R. Karberg¹, L. Waalkes¹, I. Kelbassa² (1.Fraunhofer IAPT, Germany, 2.Institute for Industrialization of Smart Materials (ISM), Hamburg University of Technology TUHH, Germany)

Keywords:material extrusion, MIM feedstock, process stability

In piston-based material extrusion, the extrusion encounters interruptions due to air inclusions in the plasticized feedstock. This study aims to reduce these air inclusions by investigating the influence of vacuum during the plasticization of Catamold 4340, a high-viscosity polyoxymethylene (POM)-based industrial metal injection molding feedstock. Plasticization and extrusion using just piston force, pre-compression at ambient temperature, and vacuum-assisted plasticization are examined to minimize entrapped air. Continuous extrusion was recorded and analyzed using computer vision to assess the effectiveness of these strategies. The results showed that both vacuum-assisted extrusion and piston force extrusion had the fewest interruptions, with vacuum-assisted extrusion performing slightly better as entrapped air was only measurable at the beginning, likely due to nozzle leakage. Conversely, pre-compression at ambient temperature resulted in a significantly higher number of interruptions, making it the least suitable plasticization strategy.