Influence of aerostatic-bearing-integrated setter plates on friction during sintering of metal binder jetting components

Abstract

Distortion of metallic binder jetting parts during sintering is partly caused by friction at the component–setter plate interface. The present study evaluates porous alumina setter plates with an integrated aerostatic bearing effect as a means of mitigating friction. Five plates with open porosities ranging from 25% to 43% and different median pore diameters were characterized. Friction tests using 17-4 PH specimens were carried out at 20 °C and 1100 °C ambient temperatures in an argon atmosphere, with a pressure difference of up to 240 mbar applied across the substrate. A linear increase in net volumetric gas flow was observed with rising differential pressure, accompanied by a linear decrease in both static and dynamic coefficients of friction. The most porous plate achieved average reductions of 91% in static friction and 92% in dynamic friction at room temperature; in some test cycles of a measurement series, even complete separation of the contact surfaces was realized. At 1100 °C, design-induced leakages limited the reductions to 34% (static friction) and 43% (dynamic friction); extrapolation nevertheless indicates that friction-reduction conditions comparable to those at room temperature should be attainable under optimized high-temperature configurations.