The effects of binder components in wax/oil systems for metal injection molding

Three wax/oil-based binders were formulated for metal injection molding of stainless steel 316L. The differences in formulation were the molecular weights of the backbone polyethylenes and the partial substitution of wax by palm oil. Solvent debinding was carried out in petroleum ether at 30/40 °C and followed by a short resoaking in clean petroleum ether to remove the residual wax. The rest of binder could be thermally extracted at 370 °C with a high heating rate of 300 °C, with no defects. Sintering was done in H2 atmosphere at 1300–1400 °C. Approximately, 96% theoretical density, hardness of 65 HRB, tensile strength of 500 MPa and Young modulus of 9 GPa were achieved with all three binders. The palm-oil-substituted binder produced much higher of ductility of 47% compared to 37% for the wax-only binders.