Metal Injection Molding

MIM

1. Basic Principle

Metal Injection Molding (MIM) is an advanced manufacturing process that combines the benefits of powder metallurgy and plastic injection molding. It is ideal for producing complex-shaped, high-precision metal parts in large volumes, using materials such as stainless steel, tool steel, nickel alloys, and titanium alloys.

Commonly used in electronics, medical devices, and high-performance tools, MIM enables cost-effective production of intricate parts that would be difficult or expensive to machine.

2. Process Overview

  • Feedstock Preparation
    Fine metal powders are mixed with thermoplastic binders to form a flowable material called feedstock.
  • Injection Molding
    The feedstock is injected into a mold using standard plastic injection machines to form the desired shape.
  • Debinding
    The binder is removed from the molded part using thermal, solvent, or catalytic methods, leaving behind a porous “brown part.”
  • Sintering
    The debound parts are sintered at high temperatures (just below the melting point) to fuse the metal particles into a dense, solid structure.

3. Key Advantages

  • High Precision: Dimensional tolerances of ±0.3% to ±0.5% are achievable, often eliminating the need for secondary machining.
  • Design Freedom: Enables the production of complex geometries, including internal channels, undercuts, and thin walls.
  • High Material Utilization: Minimal material waste, making it cost-effective and environmentally friendly.
  • Scalability: Once the mold is built, tens of thousands of identical parts can be produced with consistent quality.
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4. comparison between (MIM) and (PM)

Aspect

Metal Injection Molding (MIM)Conventional Powder Metallurgy (PM)
Shape Complexity✅ Very high – supports internal channels, undercuts, thin walls⚠️ Limited – suitable for simple geometries
Dimensional Tolerance±0.3% to ±0.5% – high precision±1% to ±2% – lower precision
Mechanical Properties✅ High density (96–98%), good strength⚠️ Lower density (80–90%), reduced strength
Material OptionsWide range – stainless steel, titanium, nickel alloys, etc.Mostly iron-based materials
Per-Unit Cost (Volume)Low at scale – cost-effective after toolingVery low – especially for simple parts
Typical ApplicationsElectronics, medical devices, wearables, micro gears, etc.Gears, bushings, washers, self-lubricating parts, etc.

Summary Recommendations

 

ScenarioRecommended Process
Complex geometry + high precision needed✅ MIM
Simple shapes + ultra-low cost needed✅ PM
Large parts with low strength requirements⚠️ PM likely
Small parts + fine details + high strength✅ MIM

Application of MIM

Common Application

Whether for innovative designs or high-volume production, Metal Injection Molding offers a reliable and efficient solution for precision manufacturing.

smartphone sliders, laptop hinges, connectors, camera brackets, etc.

smartwatch casings, earbud components, metal buttons, decorative parts.

micro surgical tools, clamps, dental probes, orthodontic brackets.

fuel system parts, transmission micro parts, sensor housings.

micro gears, tool holders, wear-resistant pins, locating latches.

firearm components, knife parts, metal fittings on tactical gear.

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