Use of high Melt Flow Rate Poly(oxymethylene) in Binders for Metal Injection Moulding Feedstocks

Poly(oxymethylene) (POM) is widely used in for metal injection moulding (MIM) feedstocks, due to its high strength and clean removability. The intent to use high melt flow rate POM was to improve processability, enabling more intricate parts, or processing at lower process temperatures. The processability of different feedstocks, prepared with such a POM-type, was investigated regarding the effects of metal powder type (316L, 17-4 PH), particle morphology (gas- and water-atomized), as well as different mixing procedures (ZX-blade mixer with and without subsequent shear roll extrusion). Feedstocks of all variations could be processed properly, but the most promising results were shown by feedstocks using gas-atomized powders and both mixing procedures. In that case, due to the good flowability, the feedstock injection step was very smooth and led to the smallest process deviations. This was shown by analysing the process data and the characterization of green and sintered parts.