MIM Process

Mental Injection Molding Process

Metal Injection Molding (MIM) is a manufacturing process that combines the design flexibility of plastic injection molding with the strength and high density of metal materials. It is a cost-effective method for producing complex-shaped metal components with tight tolerances.

The MIM process starts with a mixture of fine metal powders and a binder material, which is usually a thermoplastic or a wax. This mixture, called feedstock, is heated and injected into a mold cavity under high pressure, similar to traditional plastic injection molding. The mold is typically made of steel and is designed to create the desired shape and features of the final part.

Once the feedstock fills the mold cavity, it is cooled and solidifies, forming a “green part” that consists of the metal particles bonded together by the binder material. The green parts are then carefully removed from the mold and go through a debinding process, where the binder material is removed using thermal, solvent, or catalytic methods. This leaves behind a porous structure known as a “brown part.”

The brown parts are then subjected to a high-temperature sintering process, where they are heated in a controlled atmosphere. During sintering, the metal particles fuse together, resulting in a fully dense and mechanically strong metal component. The final dimensions and properties of the part are achieved during this stage.

After sintering, additional finishing operations like machining, polishing, or coating may be performed to meet the desired specifications and surface finish requirements. The end result is a complex, precise, and often small-sized metal component with excellent mechanical properties.

MIM Process

Compounding

The Metal Injection Molding (MIM) process begins with preparing the feedstock, a blend of fine metal powders and binders, essential for ensuring the quality and consistency of the final products.

Injection

Like plastic injection molding, the MIM feedstock is heated to about 200°C in the machine, injected into a mold under high pressure, and after cooling, forms a “green part.”

Debinding

After injection molding, “green parts” undergo the degreasing process, where binders are removed using either the catalytic or solvent method in a degreasing furnace for about 12 hours. Post this process, the parts are referred to as “brown parts.”

Sintering

In the sintering furnace, “brown parts” are heated near their melting point in a nitrogen atmosphere, bonding the metal particles and achieving final strength and shape, with an approximate shrinkage rate of 20%.
Scroll to Top