Metal Injection Molding(MIM) is an advanced technology, which allows complex and intricate parts to be produced in high-volume at a low cost. MIM technology integrates the shape making capabilities of plastic injection molding with the material flexibility of powder metallurgy. It’s an unique technology and a breakthrough in manufacturing as it provides a low-cost alternative to machining, investment casting, and stamping, and offers a wider spectrum of design opportunities which would not have been possible with traditional manufacturing methods, ranging from trigger mechanism for firearms to optic modulators used in fiber-optic networks. Using extremely fine metal powders, MIM technology produces parts in high-density and near net-shape with the properties approaching that of wrought material. Ferro-nickel alloy, stainless steel, cemented carbide alloy, and other non-ferrous alloys such as titanium, are common materials for MIM.

Mold Making

Molds similar to those used in conventional plastic injection molding are designed and fabricated. CAD/CAM technology is used to enhance the design and fabrication process.

Mixing

Fine metal powders, thermoplastic binders and other proprietary materials are mixed to form a homogeneous feedstock.

Molding

Conventional injection molding machines are used to create “green parts.” These parts are typically 15-20% larger than the finished product.

Debinding

Green parts are exposed to heat, solvent or a combination of both to remove most of the binder material. The de-bound are called “brown parts”.
Sintering

“Brown parts” are sintered in vacuum-type furnaces. The intense heat shrinks the parts 17-22% to almost complete density, however the shrinkage has already been taken into consideration when the molds are designed. The parts are then complete. Also, secondary machining or surface treatment is available.

MIM applications are ideally suited for components that are relatively complex, very small, and will be produced in large quantities, at the same time requiring high strength, high performance and cost efficiency.
1. Complexity. The components can be created with complex-geometry features such as cross-drilled holes, threads and thin walls, usually requiring no secondary machining.
2. Material properties. Parts produced through the MIM process are comparable in density and strength to those made from wrought metal.
3. Tolerances. +0.03mm ~ +0.05mm per cm.
4. Finish. Typically around 1μm.
5. Quality. Computer controlled automatic production allow for the parts to be produced in large quantities while maintaining consistent quality.
6. Cost efficiency. MIM is a cost-effective alternative to other types of metal processes, such as machining and casting.

1. Automotive: airbag firing pins, power window system, safety belts, jacking systems of auto doors, small gears, auto AC systems, turbo fans racks of braking systems, and sensors of fuel systems.
2. Firearms: small arms parts, armour-piercing bullet core, fuzes.
3. IT industry: typewriters, hard disc drive parts, magnetic cores, axle pins, and porcelain plugs of fiber optical communications.
4. Tools: drill bits, clamps, nozzles, thread milling cutters, pneumatic tools, and fishing gears.
5. Medical instrument: orthodontics brackets, laparoscopic parts like graspers, dissectors, tweezers and instrument handles.
6. Electronics: Mini motors, connecters, mobile phone hinges, keys and sensors
7. Other applications: watchcases, watch chains, electric toothbrushes, scissors, golf heads, jewelry links, cutting tools and locks.