The cause of air bubbles in zinc alloy die casting

Do you know the reason why zinc alloy die casting is easy to produce air bubbles? 

Causes of bubbles: 1. Causes of holes: mainly pores and contraction mechanism, pores tend to be round, and contraction is irregular. 

1. Causes of bubbles in zinc alloy die casting: 

1. Caused by holes: mainly the stomata and contraction mechanism, stomata are often round, and contraction is mostly irregular. 

Causes of stomata: 

A. In the process of filling and solidification of liquid metal, holes are produced on the surface or inside of the casting due to gas intrusion. 

B, the coating volatile gas invasion. 

C, the alloy liquid gas content is too high, solidification precipitation.

  

When the gas in the mold cavity, the gas volatilized by the coating and the gas precipitated by the alloy solidification are not good in the mold exhaust tank, they will eventually stay in the pores formed in the casting. 

Two, zinc alloy die casting causes of shrinkage cavity: 

A. Shrinking cavity occurs in the solidification process of liquid metal because the volume shrinks or the final solidification site is not fed by liquid metal. 

B. The casting with uneven thickness or the local overheating of the casting causes the solidification of a certain part to be too slow and the surface to be concave when the volume shrinks.  Due to the existence of pores and shrinkage holes, the casting surface treatment, the hole may be water, when the spray painting and plating after baking, the gas in the hole heated expansion or the water in the hole will become steam, volume expansion, resulting in casting surface bubbles.