Zinc Die Casting is now widely used in various decorations, such as furniture accessories, architectural decoration, bathroom accessories, lighting parts, toys, tie clips, belt buckles, various metal buckles, etc., so everyone is concerned about the surface of the casting The quality requirements are getting higher and higher, and there are different standards for the appearance and smoothness of the surface. But the most common surface defect for zinc die castings is blistering.
(1) Defect characterization: There are small protruding bubbles on the surface of die casting. ·
Foaming appeared again after die casting. ·
Protruding bubbles are revealed after polishing or processing. ·
This phenomenon occurs after oil injection or electroplating.
(2) Cause:
Pores: Mainly caused by pores and shrinkage mechanism. In general, pores are mostly circular, and most of the shrinkage are irregular patterns.
Causes of stoma
a In the process of filling and solidification, the molten metal is invaded by gas, resulting in holes on the surface or inside of the casting.
b Air holes will be generated when the gas from the paint invades.
c The gas content of the alloy liquid is too high and will precipitate during solidification. In this case, the gas in the cavity, the gas volatilized by the coating, the gas precipitated by the alloy solidification and other gases are left in the casting to form the pores when the mold exhaust is poor.
[1] Causes of shrinkage
a During the process of molten metal solidification, shrinkage cavities are generated due to the shrinkage of the volume or the fact that the final solidified part cannot be fed by the molten metal.
b Castings with uneven thickness or local overheating of the castings cause a certain part to solidify slowly, so the surface will form a recess when the volume shrinks.
Due to the existence of pores and shrinkage holes, the holes may enter water during the surface treatment of the die-casting parts. When baking after painting and electroplating, the gas in the holes will be heated and expanded; or the water in the holes will become steam and volume expansion, etc. , Resulting in blistering on the surface of the casting.
For more details about zinc die castings, please visit: China Zinc Die Casting Manufacturer .
