Breif Introduction of MIM process

Metal powder precision injection molding is a molding process that combines traditional powder metallurgy and plastic injection molding, also known as MIM (Metal Injection Molding) molding process. Specifically, metal powder and plastic binder are mixed and formed in a mold, and then degreased and sintered to produce metal parts.  

Compared with ordinary injection molds, they have some unique features in the design of molded parts, pouring systems, cooling systems, and demolding systems.

In terms of molded parts: 1. The shrinkage rate is different because the parts not only contract during injection molding, but also contract after sintering and degreasing. 2. The demolding angle is different, and MIM injection molds have a large demolding angle, usually taken as 1-3 °. 3. The roughness of the cavity is different, and MIM injection molds are higher than ordinary injection molds. Generally, Ra0.4 is taken. 4. The requirement for material wear resistance is higher because the raw material contains metal powder, which has greater friction and wear on the mold cavity. MIM injection molding parts must be made of wear-resistant steel and undergo quenching or surface nitriding treatment.

Pouring system design: MIM injection molds should use circular cross-section runners as much as possible. Metal powder is a precious metal, and the length of the flow channel should be shortened as much as possible and there should be fewer bends.

Cooling system: The diameter of the cooling water pipe is 2-4 millimeters larger than that of a regular injection mold.

Demolding system: The plasticity and rigidity of the parts are poor, and the layout of the ejection must be sufficient and balanced.

Comparison of MIM and investment casting molding capabilities

Advantages of powder injection molding:

Like the production of plastic products, a molding production of complex shapes of metals, ceramics and other parts parts of low cost, good finish, high precision (± 0.3% ~ ± 0.1%), generally without subsequent processing of the product strength, hardness, elongation, and other mechanical properties of high, good abrasion resistance, fatigue resistance, organization and uniformity of raw material utilization rate is high, high degree of automation of the production process is simple, can be a large number of consecutive production No pollution, the production process is clean technology production

Powder Injection Molding Material Applications
 Newer MIM material system applications

Comparison of powder injection molding technology with other molding process technology

The powder injection molding process has extremely obvious advantages over traditional batch industries with automated parts processing, stamping, forging, precision casting, and powder metallurgy.

Powder Injection Molding Process Flow Diagram

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