The effect of wax composition on the injection molding of carbonyl iron powder with ldpe

Abstract

The effect of waxes on the injection molding of carbonyl iron powder with low-density polyethylene (LDPE) have been examined. Four waxes, paraffin wax (PW), polyethylene wax (PEW), carnauba wax (CW) and acrawax (AW) were selected and compared. Experimental results indicated that the LDPErich phase was found to be separated from the wax-rich phase in the binder mixture containing AW, CW or PW. Polar AW or CW showed stronger interactions or adsorptions with iron powder than other nonpolar waxes. AW/LDPE and CW/LDPE mixtures appeared to exhibit higher viscosity, greater pseudoplasticity and lower flow activation energy than PW/LDPE and PEW/LDPE mixtures. Tensile bar specimens of all binder mixtures could be injection molded at an injection temperature of around 170–190 °C. and a pressure of around 5–6 MPa. Except for the PEW/LDPE mixture the parts derived from the other three binder mixtures showed good surface appearance following debinding and sintering. Specimens based on the PW/LDPE mixture exhibited the highest tensile strength in the resulting sintered parts, followed those based on CW/LDPE, AW/LDPE, and PEW/LDPE mixtures. The difference in tensile strength of each part results from different flow properties of each wax/LDPE mixture