Metal Injection Molding technology – Transforms a Precision Metal Components
Serving the demanding needs of the manufacturing industry
Today’s manufacturing industry designers are faced with extracting higher performance from smaller and more complex components and assemblies, in their pursuit of miniaturization. Achieving this requires system and component designs that can run at extremes in temperature and wear with the need to be reliable, lightweight and low cost. Metal injection Moulding (MIM) is an emerging metal forming technology across the world which is being now popularly used for the small, complex, precise and net shape metal parts.
Metal injection Moulding Technology evolved from Plastic injection moulding and Powder metallurgy and is used for manufacturing complex-shaped precise metal parts. It combines the design flexibility and production scale of plastic injection moulding with the strength and integrity of wrought metals to offer cost effective solutions to meet these demands.
Designing metal parts as you would for plastic injection moulding allows MIM the unique ability to manufacture complex, lightweight shapes that are not economically viable with other metal forming processes. Minimising part wall thickness by proper use of coring and ribs, use less metal without sacrificing durability. Besides superior shape capability, the MIM process provides the designer with a wide choice of high strength ferrous and stainless steel alloys as well as wear resistant and high temperature super alloys.
MIM has been used primarily in the defence parts manufacturing, whereas other important sectors to emerge have been in consumer goods, sports, telecommunication devices, medical & dental devices and hand & power tools. In the recent times, it has gained popularity in the global automotive sector as well.
The manufacturing industry demands parts with high performance and even higher reliability at a competitive cost and MIM meets this challenge
MIM has the following inherent capability because of which it is one of the best suitable manufacturing processes for small, complex metal parts for manufacturing applications.
- Product Design:
MIM can produce any shape that can be produced in thermoplastics by injection moulding with certain limitations to this general rule in both cases.
It offers various design advantages like manufacturability of features like hexagonal, square, splined, blind and flat bottom holes even at angles to each other, Knurled features , External / internal threads Logo / Part number / Raised letters / Impressions or Cavity ID are feasible. The various parts in the assembly can be integrated in to single piece design reducing manufacturing cost and the lead time.
- Material variety:
Most of the metals and alloys available in MIM grade powder form can be processed by Metal Injection Moulding. But the metals and alloys that melt at temperature over 1000 Deg C (1832 Deg F) are more successfully processed by MIM.
For complex chemistry, there are three possible starting forms – Mixed elemental powders, fully compounded powders, or a hybrid of partially compounded and elemental powder. If the material is available or can be custom fabricated as a small powder then MIM is a viable production route. Of course, powder cost impacts the final component cost but the powder availability is the first consideration.
Selection of the proper material for a particular application often decides the success of a MIM project. The decision is made based on performance, cost, and input from a MIM part supplier or expert.
MIM materials have various advantages like Homogeneous microstructure and Isotropic material properties. Parts can be fabricated out of difficult to melt alloys like tungsten heavy alloys with no interconnected porosity which is normally present in the PM parts.
- Prototyping and low volume development
The low cost single cavity tools can be made for prototype and low volume development. We can produce few components which will be tested for functional tests before going for high volume production by which automotive manufacturers can validate the design by using the same production process as the one for high volume production.
- High Volume production
The need of manufacturing technology for small, precise, complex-shaped parts in large volumes with short lead times and at competitive price has triggered the MIM technology. The multiple cavity tooling with automation can be made for high volume production.
- Automated manufacturing and inspection
The MIM process can be automated similar to plastic injection moulding and powder metallurgy manufacturing process, including online inspection.
- Secondary machining process and secondary finishing process
MIM parts are amenable for all the secondary operations similar to the ones on wrought or cast materials, like heat treatment, surface treatment, machining and joining and hipping operations, so they can be finished to any requirements as per the product design.
Production Quantity Vs Shape Complexity:
Below figure shows the suitable metal forming process for a component with particular shape complexity and the production quantity requirements.
The above diagram shows that ideally Metal injection Molding (MIM) is suitable for high complexity components with higher production volume requirements.
Unit cost of manufacturing Vs Shape Complexity:
Below figure shows the relative unit cost of manufacturing for a component with particular shape complexity.
The above diagram shows that ideally Metal injection Molding (MIM) is suitable for high complexity components with higher production volume requirements. The more complex the part, the more cost effective metal injection molding (MIM) becomes.
