Metal Injection Molding (MIM) Parts | SDM Magnetics Co., Ltd.

Manufacturing Process of Metal Injection Molding (MIM) Parts

The manufacturing process for metal injection molding (MIM) parts starts with mixing fine metal powders with binder materials, such as wax and polypropylene, and granulating them to create a uniform feedstock. Next, the feedstock is loaded into a standard injection molding machine, heated, and injected under high pressure into a mold cavity to form the “green part.”

After that, the green part goes through debinding using methods like solvent extraction, thermal furnaces, catalytic processes, or a combination of these to remove the binder, resulting in a “brown part.” The brown part is then sintered in a high-temperature furnace with a controlled atmosphere, where any remaining binder is removed, and the metal particles bond together to densify the part, causing it to shrink to its final size. Finally, optional secondary operations like machining, heat treatment, or surface coating can be applied to MIM parts to meet specific requirements.

Materials Guide for Metal Injection Molding (MIM)

The metal injection molding (MIM) process uses a wide range of materials and provides mechanical properties that match or exceed those from traditional wrought or cast methods. SDM offers a broad selection of MIM materials, including stainless steel, soft magnetic alloys, low alloy steel, high density alloys, tool steel, and superalloys, to meet various application needs.

Materials Available for Metal Injection Molding (MIM)

Alloy group	Specific alloys	Description
Stainless steel	17-4PH, 316L, 304, 420, 430, 440, 2507, PANACEA, F75.	Steel alloys show enhanced resistance to corrosion and heat because of their elevated nickel and chromium levels. Thus, these attributes render them especially appropriate for crafting surgical instruments in the medical sector.
Soft magnetic alloy	FeSi3, FN50, FeCo35, FeCo50, FeCo49V2, Ni80.	Soft magnetic steels possess high magnetic permeability, making them highly responsive to magnetic fields. This property renders them ideal for applications in solenoids, electric motors, and relays.
Low alloy steel	FN02, FN08, G1010, 8620, 8740, 4340, 100Cr6, 42CrMo4, SCM415.	Low-alloy steels, characterized by their low carbon content and minimal alloying elements, offer improved machinability and cost-effectiveness.
High density alloy	W-Ni-Fe, W-Ni-Cu, W-Ni-Co.	High density alloys, mainly consisting of tungsten and diverse alloying elements, are chiefly utilized for electromagnetic shielding applications due to their remarkable density.
Tool steel	M2, SKD11.	Tool steel, with its high carbon content, exhibits exceptional hardness and abrasion resistance. These properties, combined with stringent quality checks, make it ideal for the production of cutting tools and mold tools.
Superalloy	Ti/Ti-6Al-4V, F15, 4J29, GHS-4, HX, N90.	Superalloys are engineered for exceptional performance in extreme environments, offering outstanding strength, resistance to thermal creep deformation, and excellent corrosion and oxidation resistance. Ideal for high-stress applications such as aerospace components, gas turbines, and high-performance engine parts.

Advantages of Metal Injection Molding (MIM)

Complex geometries: MIM enables the production of intricate shapes t hat are challenging or unachievable with conventional manufacturing methods.
High precision: MIM produces metal injection molding (MIM) parts with precise tolerances and smooth surface finishes.
Material efficiency: MIM uses nearly all the material, minimizing waste and reducing costs for raw materials in production.
Mechanical properties: MIM parts offer mechanical properties that match or surpass those of parts made by traditional methods.
Large-scale production: MIM is well-suited for high-volume manufacturing, making it a cost-effective choice for producing metal injection molding (MIM) parts in bulk.

Disadvantages of Metal Injection Molding (MIM)

High startup costs: Tooling and setup expenses for metal injection molding (MIM) can be significant, making it less ideal for prototyping or small batch production.
Size constraints: MIM is typically suited for small to medium-sized parts, with limitations on component size and weight.
Binder removal challenges: The debinding process is time-intensive and demands precise control to avoid part imperfections.
Shrinkage issues: MIM parts shrink during sintering, which complicates design and manufacturing processes.

Integrating MIM Parts with Permanent Magnets

Magnetic assemblies combine permanent magnets with components like stainless steel and soft magnetic alloys to achieve specific functional properties. Sourcing all parts from a single supplier simplifies coordination, inspection, and inventory management of multiple components. This approach also reduces tolerance stack-up, lowers labor costs, and minimizes scrap rates.

The metal injection molding (MIM) process enables the creation of a single, precisely molded part from multiple components, reducing the need for multiple manufacturers and cutting both processing and assembly costs.

Additionally, MIM produces magnetic assemblies with strong mechanical properties, tight tolerances, and smooth surface finishes. High-performance alloys made through MIM are now widely used alongside permanent magnets in products like watch cases, plugs, and hinges for consumer electronics.