Die Casting Design of Magnesium Alloy

Because the chemical, physical parameters and die-casting characteristics of magnesium alloys are quite different from those of aluminum alloys, the design principles of aluminum alloy die-casting molds cannot be fully applied to the design of the mold.

Magnesium alloy liquid is easy to oxidize and burn, and has a greater tendency to hot crack during casting than aluminum alloy. It is more complicated than aluminum alloy die casting in terms of melting, pouring and die casting temperature control. The filling time of magnesium alloy is short, and the exhaust problem is particularly prominent. The specific heat capacity and latent heat of phase change of magnesium alloy are lower than that of aluminum alloy. Therefore, crystallization in advance is easy to occur in some parts (thin section parts), leading to the blockage of the feeding channel, thus causing insufficient pouring. The design of magnesium alloy die-casting mold mainly considers the following aspects:

Magnesium alloy die casting machine selection

The type of die casting machine used for production mainly depends on the wall thickness of the casting. In the process of researching the "Optimization of Magnesium Alloy Die Casting Process", ROLANDFINK analyzed the economics of magnesium alloy die casting, cold chamber die casting and hot chamber die casting process, and proposed that, in general, castings less than 1KG need to use a hot chamber die casting machine. In order to ensure the filling of thin-walled parts, cold chamber die casting machine is recommended for large parts.

Process parameters of magnesium alloy castings

In the die-casting production process, selecting the appropriate process parameters is a prerequisite for obtaining high-quality castings to maximize the productivity of the die-casting machine, and is the basis for the correct design of the die-casting mold. During die-casting, there are many factors that affect the filling and forming of the alloy liquid, mainly including injection pressure, injection speed, filling time and die-casting mold temperature. Due to the different wall thickness and complexity of die castings, the selection of process parameters can vary widely. Compared with aluminum and zinc alloys, magnesium alloy has better fluidity, so the secondary injection speed can be greater. The punch speed of magnesium alloy is about 30% faster than that of aluminum alloy, and the maximum is even more than 10M/S. Since the casting properties of magnesium alloys such as fluidity are very sensitive to mold temperature and pouring temperature, the magnesium alloy liquid is very easy to solidify during the mold filling process, and the mold temperature and pouring temperature must be accurately controlled, otherwise it is easy to produce waste.