Magnesium alloys is an extremely low density and high strength-to-weight ratio. The magnesium parts combine the advantage of both aluminum and zinc alloy part. The disadvantage of magnesium is that it is easy to creep(cold flow), Because of this, magnesium parts should not be used in very high stress or very high temperature environments.
Magnesium is one of the most easiest metal to machine. It is the only lightweight metal to undergo high pressure die casting, which can be designed as very complex part structure.
Magnesium can be produced in either a hot or cold chamber, but most of time, we produce magnesium die casting parts by hot chamber machine. In some case, magnesium casting process is quite dangerous as magnesium has very low melting point that easily get burned. Therefore we should take care of it when production.
The manufacturing process of magnesium die casting is very similar to aluminum and zinc, it could be casted with both cold chamber casting machine and hot chamber casting machine. However, in recently years it relatively tends to manufactured by the latter one. Here below we would like to discuss the key parameter of magnesium die casting process.
Since there are two different types of magnesium casting process as hot chamber casting and cold chamber casting. Certainly they should have different injection pressure. Normally the injection pressure for hot chamber process is about 40 Mpa, but the cold chamber process will be a little bit higher as 40~70 Mpa.
On the other hand, a pressure-added time of magnesium die casting process should be within 20 seconds, because magnesium alloy has a low solidification point(much shorter than aluminum), and the molten material would solidifies very quickly when it arrives in the mold cavity.
The density of magnesium alloy is very small(1.78-1.83g/cm3), it is the lightest casting metal with very quick solidification time. Therefore the magnesium die casting process requires as a quicker injection speed as possible. Normally we utilize 6 m/s for hot chamber casting machine, and 8 m/s for cold casting machine.
Temperature is an important factor of casting process, it should be set properly to provide best material filling condition so as to obtain high quality casting products. It mainly includes injection temperature and casting mold temperature.
The injection temperature of hot chamber casting machine is about 640 °C, while a cold chamber casting process is about 680 °C. (Max. 700 °C)
The mold temperature of magnesium casting process is about 200 °C.~250 °C. a improper mold temperature would result in many casting defects, like unstable dimension, deformation, unfulfilled parts, etc.