Magnésium

Vacuum die casting of magnesium offers considerable advantages over conventional die casting.

The high productivity that can be achieved by die casting, on the other hand, has the disadvantage of a possible high level of porosity due to trapped gases resulting from the injection of molten metal at very high speeds required by the die casting of magnesium alloys. The problem of porosity is less serious for thin-walled sections where mechanical properties are largely provided by fine-grain, pore-free casting skins. When thicker walls are needed for their rigidity in critical structural applications, the effect of porosity on mechanical properties (especially ductility and fatigue resistance) is more sensitive.

Vacuum die casting of magnesium is an innovative process in which, the reduced pressure created in the injection chamber and mold cavity just before injection, leaves no air trapped in the melting and allows the production of relatively large thin and/or thick wall castings with greatly improved properties. The application of vacuum in magnesium die casting also allows to an important reduction of injection speeds thanks to the absence of air pressure in the mold.

Lower injection speeds therefore leads to less wear of the mold and equipment. The castings produced by this process are currently intended for components that require pressure tightness and good mechanical properties by heat treatment. Vacuum die casting therefore extends the capabilities of conventional die casting while preserving its economic benefits.