Metal Injection Molding

Metal injection molding (MIM) is a hybrid technology which integrates the shaping capability of plastic injection molding and materials flexibility of conventional powder metallurgy. MIM is preferred for mass manufacturing of small, intricate geometric components of a variety of materials as it can achieve 95% to 98% of its wrought materials properties at a much lower cost.

Technology

The initial step to MIM is material selection and preparation. Once the appropriate combinations of metal powder and plastic binders are blended and compounded, an injection moldable feedstock is produced.

Using an injection-molding machine, the parts produced are then subjected to a binder removal process. Depending upon the type of binder used, different methods of debinding are applied.

The parts, after debinding, then go through a sintering process to ensure the parts are of the right material composition, physical properties and correct geometry.

 

Process Overview

MicroMIMProcess

Advantages

Greater design freedom

With MIM, parts can be designed and manufactured without any design restrictions. In addition, almost all design changes are possible within the shortest development cycle and turnaround time.

 

Complex and intricate shaped parts

MIM is ideal for producing complex-shaped components as well as parts that require assembly or multiple steps to put together.

 

 

High production requirements

MIM is most beneficial in high volume production of small precision parts with complicated design geometry. The process lends itself to automation where high volumes and consistent quality are required.

 

Miniaturization

MIM technology is the best viable process for producing miniature parts economically.

MIM vs. Machining

The MIM Advantage: Conventional Machining:
Ideal for complex shapes Design limitations
Highly automated process Labor intensive process
Lower Cost Costly Process
No secondary operations required Possible secondary machining steps
Virtually no material waste Significant material waste
High production volumes Lower production volumes
Molding from a single tool Muliple set-up operations required
Mold the part net shape Complex shapes require multiple operations
Thin-wall sections possible Thin walls difficult to machine
Exterior & interior threads possible Difficult to machine internal threads
Words & numbers can be molded into parts Machining words & numbers not viable

 

Applications

MIM technology has found increased applications in the commercial world – from home appliances to watches, automobiles to aerospace, and medical to orthodontics.

Materials

Due to the flexibility of MIM technology, it is possible to customize material compositions according to the specific attributes required by the customers. Some of the compositions are stainless steels, low alloy steels, carbon steels, Ni-alloys, tool steels and tungsten alloys.

Metals

Materials Grades Density (g/cm3) Hardness (Hv 10)
Stainless Steel 17-4PH 7.6 230
304L 7.8 120
316L 7.85 120
317L 7.85 150
430L 7.55 120
440C 7.55 550
Low Alloy Steels 4140 7.4 130
8620 7.4 190
Carbon Steels Low 7.7 80
Medium 7.6 130
High 7.4 320
Fe-Ni Alloys FeNi 2 7.6 90
FeNi 8 7.7 100
FeNi 50 8.05 120
Cobalt Alloys Kovar 7.8 150
49Co-2V 7.8 400
Tool Steel M2 8.05 800 (HT)
Tungsten Alloy WHA 18 450