Powder injection molding

Powder injection molding (PIM), including Metal injection molding (MIM) and Ceramic injection molding (CIM), is an advanced forming technique for producing shaped components from powders, in high volume. This process uses injection molding technology to produce small, high volume and complex parts to tight tolerances. The best applications are typically less than 100 grams in weight.

In PIM, fine metal or ceramic powder is mixed with polymeric binder material to comprise a feedstock that can be handled by plastic processing equipment. The feedstock is heated in a screw-fed barrel and injected as a liquid, under pressure into the mold cavity, where it cools and is subsequently ejected. The polymeric binder material is then removed, and the part is sintered to form the final product. The debinding stage, when the polymer is removed, can significantly affect the mechanical properties of the sintered component.

Injection of the PIM material is often accompanied by jetting and powder/binder segregation. The powder/binder mix can separate due to strong shear effects experienced during injection of the feedstock. The result of the powder/binder separation is uneven powder distribution through the part. Since the binder is eventually removed, visual defects can appear in locations where powder concentration is low. For accurate flow prediction, enable the wall slip model when you run a powder injection molding simulation.

The Powder Injection Molding process can help predict black lines that appear in the part in areas where the powder concentration in the feedstock is low. This simulation requires a model with a 3D mesh. We solve the powder and binder segregation problem using the Suspension Balance Model (SBM), which predicts the powder concentration variation caused by both convection and the shear effect. Look at the Powder volume concentration result to identify where the powder volume is unusually low.

Note: This implementation supports materials with only a single filler.
Note: Viscosity is not impacted by concentration variation.