Extrusions see the light

An aluminium company has cracked the problem of applying aluminium extrusion technology to magnesium alloys

– a major plus, as magnesium alloys are about 35% lighter than their aluminium equivalents, but with similar strengths. They were used extensively during World War II in the construction of German and Japanese military aircraft, particularly the Mitsubishi Zero fighter. It has long been recognised that the key to wider use of magnesium is finding ways to improve its corrosion resistance. “We now have three coatings that are economically viable,” says Michel Kurstjens of Mifa Aluminium. “These are available from sister company AHC. Machining of magnesium is also not easy. You can put a light to a bar of magnesium alloy and it will not burn, but burrs and chips are extremely flammable. Solving these problems is a matter of investing.” Mifa can now extrude two magnesium alloys – AZ31 and AZ61 – in any form in which aluminium alloys can be extruded. Wall thicknesses are from 0.25mm and tolerances are from 0.02mm. That makes it inexpensive to produce linear sections with complex and intricate cross-sections without having to machine them. Magnesium alloys also offer excellent fatigue properties, negligible form deviation resulting from temperature changes and the ability to absorb vibration. Applications include housings for civil and military electrical and electronic products, including communication devices and digital cameras.