MOLD-FILLING SIMULATION FOR POWDER INJECTION MOLDING

Powder injection molding is an important processing method for producing precision metallic or ceramic parts. Experience, intuition and trial-and-error have been the practice for the design and process optimization of such molding operations. However, this practice is becoming increasingly inefficient and impractical for the molding of larger, more complicated and more costly parts. In this investigation, a numerical method for simulating the mold-filling phase of powder injection molding was developed. The flow was modeled using the Hele-Shaw approach coupled with particle diffusion transport equation for the calculation of the powder concentration distribution. The transient behaviour, or the moving boundary, is handled such that the melt front advances automatically in the calculation. The viscosity of the feedstock is evaluated using a power-law type rheological model to account for the viscosity dependency on shear rate and powder concentration. An example is presented and discussed to demonstrate the capabilities and limitations of the simulation algorithm, which has the potential as an analytical tool for the mold designer.