Rheological properties of feedstock composed of titanium alloy powder and polyethylene glycol based binder system for metal injection moulding

Abstract

Metal injection moulding (MIM) has been widely recognized as a route for cost effective production of titanium alloy parts with complex shapes. In this study, feedstock was prepared by mixing HDH Ti-6A1-4V alloy powder with polyethylene glycol (PEG) based binder system. Feedstock formulation was homogeneous with a combination of dry mixing by a planetary mixer and a roller mixer, as well as melt mixing by a twin blade compounder and a twin screw extruder. Investigations were done using a capillary rheometer to understand the effects of key parameters such as powder loadings and binder formulations on the rheological properties of feedstock. Results showed that all feedstock formulations exhibited pseudoplastic flow behaviour. A feedstock consists of 86 wt.% powder loading was found to be more suitable for MIM with the feeding screw speed of 200rpm, injection pressure of 20MPa and the feed to nozzle temperature of 130 °C to 145°C.