THIXOMOULDING INJECTION MOULDING OF SEMI-SOLID MAGNESIUM ALLOYS
Institut für
Kunststoffverarbeitung (IKV), Pontstraße 49,
D-52062
Aachen, Germany
The
thixomoulding technology, i.e. the injection moulding of thixotropic,
semi-solid magnesium, represents a new, innovative and fully automated
processing technique for magnesium alloys, which combines substantial
processing elements of the magnesium die casting and the conventional plastics
injection moulding. The process technology is very similar to the injection
moulding of thermoplastics, except magnesium is being moulded. The two
objectives pursued by thixomoulding are the process substitution of die casting
of certain component parts on the one hand and the material substitution in
special fields of plastics injection moulding on the other hand. Magnesium
offers a considerable potential for material and structural lightweight
construction. Thus, by means of the thixomoulding technology, a multitude of
lightweight and mechanically high-grade net or near net shape parts can be
manufactured, requiring no or very little finishing. Thixomoulded parts can be
found in the areas of consumer electronics (for example housings for cell
phones, laptops, cameras etc.) and in the fields of the automotive industry (in
the form of thin-walled structural components). The thixomoulding process is
environmentally friendly, since small amounts of argon can be used for an inert
gas atmosphere in the mostly encapsulated plasticising unit, instead of ozone
depleting gases, such as SF6, generally used in die-casting. At the
same time, the process is operator friendly as well, since the danger of
exposure to molten magnesium is minimised due to the closed machine.
Key words: injection moulding, magnesium
alloys, semi-solid metal, precision parts