Defects and Variation of viscosity in Powder Injection Molding Filling Process
PIM充模流动过程中粘度的变化与缺陷形成

The variations and distributions of viscosity during filling process of powder injection molding (PIM)are given by numerical simulation of PIM filling intricate part.The relation between the final distribution of viscosity and the defects in PIM was analyzed.The simulated results showed that the pressure in the cavity heightens sharply at the near end of the filling stage,which induced the distribution of viscosity at the end of the filling stage is very complicated.There are some small areas where viscosity is higher than that of nearby area in the melt flowing central region.The formation and shape change of the high viscosity areas are studied.The higher viscosity areas can make the powder-binder separate or the density gradient in the component occur during PIM process.