At present, zinc alloy die casting is widely used in furniture accessories, architectural decoration, bathroom accessories, lighting accessories, toys, tie clips, belt buckles, all kinds of metal buckles and other decorative fields, so the casting surface quality requirements are high, and also require a good surface treatment performance. But a particularly common defect in zinc alloy die casting is surface bubbling. Crack performance: small bubbles protruding on the surface of die casting, found after die casting, revealed after polishing or processing, oil injection or electroplating.

The causes of cavitation are mainly air pockets and shrinkage mechanism. The air pockets are mostly round, and the shrinkage is irregular. The cause of the holes:

1. During the filling and solidification of liquid metal, there are pores on the surface or inside the casting due to the intrusion of gas. 2, paint volatile gas intrusion.

3. The gas content in the alloy liquid is too high, and it is precipitated during solidification. When the casting mold is arranged, the gas in the cavity, the gas volatilized by the coating and the gas precipitated by the solidification of the alloy are left in the casting to form the pores.

Causes of shrinkage:

1. When the metal liquid solidifies, the volume shrinks due to the shrinkage of the metal liquid or the late solidification part can not get shrinkage, resulting in shrinkage holes.

2, the thickness and thickness of the uneven casting or casting local overheating, resulting in a part of the slow solidification, volume shrinkage, surface depression. In the process of die casting, due to the existence of pores and shrinkage holes, the die casting may enter the water when the surface is treated. When the gas in the pores is painted and baked after electroplating, the thermal expansion is carried out. Or, in the process of die casting, water will generate steam and expand the volume, which will cause the surface of the casting to bubble.

The above is the introduction of some reasons for the bubbles in the holes of zinc alloy die casting parts.