MIM (Metal Injection Molding)







WHAT IS MIM ?

"MIM (METAL INJECTION MOULDING) is a part of powder metallurgy manufacturing process where the metal powder is compacted or brought to required shape likewise plastic injection molding which is followed by pre-sinter process in which secondary binder is removed. Thus giving a final product after sintering process.

Thus one can say it a unique combination of plastic injection molding and powder metallurgy. This combination is industrially beneficial technology for allowing engineers to create complex shaped tiny metal parts which are complicated in design.


Increase in complexity increases cost of production in traditional method. Operation such as internal/external threads, miniaturization, or brand identity marking, typically do not increase the cost in a MIM operation due to the flexibility of injection molding, thus the window of economic advantage in metal injection molded parts lies in complexity and volume for small-size part i.e. greater is the complexity and volume requirement then lesser is the cost of production in comparisons to other manufacturing method.

MIM Applications

Medical
Biopsy Cups, Dissectors, and Instrument Handles, as well as Hearing-Aid Cans and Orthodontic Braces.

Automotive
Industrial, Sporting, Jewelry, Hand Tools, Aerospace, Firearm, Computer, Cell phone

Consumer Products
Kitchen Tools, Toothbrush Parts, Acissors, Watches, Latches, Eyeglass Hinges, and Luggage Clasps .

Industrial components
Valves, Fittings, Connectors

Electronic & Electrical Components
Heat Sinks, Hermetic Packages, Connectors.

Defence Equipments
 

MIM Comparison

METAL INJECTION MOULDING

  • Complex shape
  • High production
  • Low cost
  • Thin section
  • Better surface finish
  • Density >97%

POWDERPRESSING

  • Simple shape
  • High production
  • Low cost
  • Fill thick section
  • Good surface finish
  • Density < 90%

INVESTMENT
CASTING

  • Complex shape
  • Low production
  • High cost
  • Thick section
  • Rough surface
  • Density 97-100%

MACHINING

  • Complex shape
  • very low production
  • very high cost
  • thin section
  • very good finish
  • Density =100%

Advantages

It is process for high volume production in less time and reduced cost.

MIM can produce parts where it is difficult, or even impossible, to efficiently manufacture through other means of fabrication.
It offers greater design freedom than many other production processes by freeing designers from the traditional constraints associated with trying to shape stainless steel, titanium, high and low carbon steel and tool steel.

MIM makes it possible to integrate and consolidate several components into a single molded piece—reducing the need to work with several manufacturers and decreasing processing and assembly costs.

Texture, knurling, threads, lettering, and company logos can all be incorporated into the mold which significantly lowers costs.

Metal injection molding eliminates inclusion defects which result from unwanted material such as slag or ceramic chips that get into the molten material caused by traditional casting. Also the large pores or gas pockets that often form during traditional casting are eliminated because the material fills the mold entirely.

Since the parts are made of metal or alloy powders, purity and corrosion resistance are significantly better than with cast and wrought parts. It eliminates all long and tedious elementary machining operations.

Material

MIM allows all metal whose melting temperature is greater than 1200 degree Celsius or whose properties are similar to wrought iron.

Example

High alloy steel, Low alloy steel, Stainless Steel , Tungsten carbide , Titanium and Soft Magnetic Materials.