Engineers are increasingly turning to the amazing properties of high-tech ceramic materials for new applications. When it comes to the use of these materials in precision drives and systems, maxon motor believes itself to be at the forefront of the ceramic revolution. But while the seemingly unlimited possibilities offered by Ceramic Injection Moulding (CIM) continue to grab the headlines, maxon is also making good use of a more widely known technology - Metal Injection Moulding (MIM).
In fact, the company recently received an Award from the European Powder Metallurgy Association (EPMA) in recognition of an innovative component - the casing for an automatic guitar tuner - that unequivocally demonstrated the advantages of MIM over conventional production methods.
MIM and CIM use similar processes to turn out components whose size and often intricate shape need to be precise in every detail, so it makes sense that the expertise and resources of maxon’s ceramic division should be applied at the same time to MIM.
In MIM, fine metal powder is combined with a plastic binder and the mixture is injected into a mould. The resulting component is then placed in a furnace, set at about 1300°C, and ‘sintered’ - which means heated to a temperature high enough to make the materials bind but not so high as to melt the metal.
The products of MIM can reach 98% of the density of wrought iron and have excellent mechanical properties. With a dense, non-porous structure and high-quality surface, they can be used in applications where materials need to be gas-tight, resistant to high pressure and corrosion-free. They can also be heat-treated, polished, galvanised, welded, soldered and machined with no ill effect.
Most importantly, MIM will produce very small or complex-shaped components that require little or no machining before use. Undercutting, cross-holing, internal and external screw threads, gear teeth and many other structures can be incorporated within a single component.
Items required in large quantities can be manufactured more economically by MIM than by other methods. MIM can also reduce costs by allowing a single component with a complex shape to be produced in place of a number of smaller parts that need to be assembled to form the same thing. In the guitar tuner, for example, maxon was able to reduce the number of parts needed from 150 to 30.