3D printed plastic molds utilization for WC-15Co cemented carbide cold pressing

In this work, we propose the use of 3D printing to make molds for pressing cemented carbide compacts. The fused material extrusion technique was used to make solid molds from polylactide for pressing a rectangular standard sample and a square cutting insert. The densification of the WC-15Co powder mixture combined with rubber (2%) was studied at pressures ranging from 41 to 121 MPa in the obtained molds. A comparative analysis of the density of powder compacts and sintered products and their properties was performed against their analogs formed by pressing in a hardened steel mold at a pressure of 210 MPa. Increasing the pressure in the plastic molds from 41 to 121 MPa led to an increase in the relative density of powder compacts from 65% to 70%. The relative density of powder compacts (75%) obtained by the steel mold pressing at a pressure of 210 MPa was only 5% higher. The density of sintered samples increased from 99.22% to 99.5% when the molding pressure was increased, which was only 0.29% lower than the density obtained by steel mold pressing. The hardness (1130-1160 HV) and fracture toughness (23.1-24 MPa m1/2) of samples produced in the plastic molds differed slightly from those produced in the steel molds (1170 HV and 24.4 MPa m1/2). In terms of the hardness and fracture toughness combination, the samples obtained by this technique were superior to those obtained by the selective laser melting method and were comparable to the samples obtained by sintering of powder compacts produced by various 3D printing methods (binder jetting, 3D gel printing, material extrusion).

Automated summary

This study proposes the use of 3D printing to create molds for pressing cemented carbide compacts. Solid molds were made using the fused material extrusion technique from polylactide, and pressure was applied to obtain rectangular standard samples and square cutting inserts. The density and properties of the compacts and sintered products obtained from the plastic molds were compared to those formed by pressing in a hardened steel mold at a higher pressure.