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.
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 Options | Wide range – stainless steel, titanium, nickel alloys, etc. | Mostly iron-based materials |
| Per-Unit Cost (Volume) | Low at scale – cost-effective after tooling | Very low – especially for simple parts |
| Typical Applications | Electronics, medical devices, wearables, micro gears, etc. | Gears, bushings, washers, self-lubricating parts, etc. |
Summary Recommendations
| Scenario | Recommended 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.
- Consumer Electronics (3C Parts)
smartphone sliders, laptop hinges, connectors, camera brackets, etc.
- Wearables & Personal Devices
smartwatch casings, earbud components, metal buttons, decorative parts.
- Medical & Dental Instruments
micro surgical tools, clamps, dental probes, orthodontic brackets.
- Automotive & Motorcycle Components
fuel system parts, transmission micro parts, sensor housings.
- Industrial & Tooling Parts
micro gears, tool holders, wear-resistant pins, locating latches.
- Defense & Outdoor Equipment
firearm components, knife parts, metal fittings on tactical gear.