Automotive Metal Injection Molding applications
The automotive sector has become a major consumer of Metal Injection Molded parts. High strength, high complexity parts are used in engines, gearboxes, turbochargers, locking mechanisms, steering systems and electronic systems, to name just a few.
Rocker arms for BMW engines
A good example of a MIM rocker arm is the roller following type arm shown in Fig. 20.
This rocker arm was used for engines with a variable valve stroke and was made from low alloy steel. It featured a hollow configuration, saving weight, which is difficult to achieve by other processes.
The variable valve lift enhanced engine performance and reduced fuel consumption. Around 4.5 million parts were produced annually using a hardenable 50NiCrMo2.2 steel powder alloy.
This extremely high volume Metal Injection Molded component was part of a passenger car’s manual transmission.
The component is shown in the various manufacturing stages: moulded, sintered, hardened, and assembled with a shaft.
The material is Fe-2% Ni. The part is case hardened after sintering.
Metal Injection Molded variable nozzle vanes are produced in very high volumes for automotive turbochargers. The parts meet strict dimensional tolerance requirements, as close as ±0.015 mm on the wing profile, which is achieved with machining.
The part shown in Fig. 22 is produced using a special tool that has a unique sliding function when opening, reducing deformation during ejection. Metal Injection Moulding production offered a 20% cost saving.
The production of Metal Injection Moulded superalloy components is now far advanced, with an ever increasing market share. Materials such as Inconel 713 are readily available as MIM feedstocks.
Metal Injection Molding, thanks to the finely dispersed powders used, delivers parts with a very homogeneous microstructure, which improves significantly on the microstructures of investment cast products.
For readers wishing to get an in-depth understanding of Metal Injection Moulding in the automotive sector, the article “Metal Injection Moulding: Past successes and future opportunities in the automotive industry” is available to download free of charge in the December 2015 issue of PIM International.
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