Vacuum die casting means using vacuum to discharge gas of mold cavity.
When molten metal filling at high speed and intensified pressure, the pressure of cavity rises too.
Vacuum die casting can discharge gas through vacuum valve.
Vacuum is the most effective way to discharge gas from cavity of mold.
Defective reason of die casting products
Basic reason of die casting products is adiabatic compression which happens between molten metal and cavity. It may cause blowhole inside of products and soldering outside of the products.
Picture below shows that vacuum die casting can decrease the influence of adiabatic compression which harms the quality of die casting.
Reference document for vacuum system selection
Advice for high quality die casting
Die casting conditions of vacuum die casting
Both die casting design and length of high speed influence quality of products. If length of high speed die casting is 100%, the length of vacuum die casting is 110%.
Timing of vacuum start is 0.4sec before high speed start.
