Mixing and feedstock preparation for micro-cemented carbide injection molding

Mixing powder and binder and preparation of feedstock have great importance in micro-cemented carbide injection molding (micro-CCIM) process because the lack of feedstock quality can not be adjusted by subsequent processing. This research was focused on mixing of submicron cemented carbide (WC-Co-VC) powder and binder and effect of solid loading on feedstock preparation. WC-Co-VC powder particle size and morphology were analyzed by laser diffraction and field emission scanning electron microscopy (FE-SEM). The WC-Co-VC powder was kneaded with a paraffin wax (PW) based binder system using a Brabender mixer. Based on critical solid loading, the feedstock with different solid loadings between 49 vol.% to 51 vol.% was prepared. Finally, the flow behavior of different feedstocks was investigated. Morphology of powder revealed that the particles of powder are slightly agglomerated and irregular in shape. The result of mixing indicted that the torque value increases as the solid loading increase from 49 vol.% to 51 vol.%. The feedstock exhibited sufficient homogeneity and the powder particles after mixing are homogenously coated with binder. The feedstock with solid loading of 51 vol.% is sensitive to temperature and showed high viscosity values. But the feedstock with solid loadings of 49 vol.% and 50 vol.% had good compatibility and flow characteristics.

Keywords:

Micro-cemented carbide injection molding , Mixing , Feedstock , Rheology