Study of Polytetrahydrofuran on Polyoxymethylene-Based Binder in Metal Injection Molding

The feedstock prepared by polyoxymethylene (POM)-based binder usually has high viscosity and poor fluidity in the injection process, which can easily cause defects such as insufficient injection, flow lines and cracking and has great wear on the injection equipment. In this experiment, in order to further improve the performance of POM-based binder, polytetrahydrofuran (PTHF) is used to modify POM-based binder. The results show that the effect of PTHF on improving the rheological properties of feedstock is better than that of acid (SA). When the content of PTHF is 3 wt%, the non-newtonian index ( n ), viscous flow activation energy ( E ) and comprehensive rheological factor ( α STV ) of the feedstock are 0.39, 16.63 kJ/mol and 13.33 × 10 –7 , respectively, at 185 °C and 965 S −1 shear rate, which means feedstock has a good comprehensive rheological performance. In addition, PTHF has no obvious effect on the mechanical properties of green part and is removed in the catalytic degreasing stage.