Effects of particle characteristics on homogeneity of green bodies in powder injection moulding

Abstract

A homogeneous powder and binder distribution in the green body in powder injection moulding (PIM) is important. In the present study, the mould filling model of PIM has been developed, based on the multiphase fluid theory, viscosity model of feedstock and powder-binder drag force model. The particle Reynolds number is influenced by the particle size and density, resulting in the different drag force between powder and binder. Furthermore, the varied velocity of binder and powder will be obtained with numerical calculation of the continuity equations, leading to the change of green body homogeneity. CFX was used to simulate the mould filling in PIM. The results showed that the homogeneity of green bodies was relative to the filling patterns, which varied with different powder densities. The powders were not suitable for PIM when the particle size was bigger than 20 μm, and the fine powders were beneficial to improve the homogeneity.

Keywords:

• Powder injection moulding
• Particle density
• Particle size
• Particle Reynolds number
• Homogeneity

Acknowledgements

This work was financially supported by the Major State Basic Research Development Program of China (973 Program) (2011CB606306), the Fundamental Research Funds for the Central Universities (FRF-TP-10-003B) and the National Nature Science Foundation of China (51274040).