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Causes and improvement measures of shrinkage in Zinc Alloy Die Cast Part

Dec. 09, 2019
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Pressure casting (referred to as die-casting) is a method of making liquid or semi-liquid metal under high pressure to fill the mold at a very high speed and solidify under pressure to obtain a casting. Products with high dimensional accuracy and mechanical properties, high productivity, and low or no machining allowances are widely used in automotive, aviation, electronics, machinery, hardware and other fields. In recent years, China Die Casting parts Factory, with the rapid development of the automotive industry, the scope of application of die castings in the automotive industry has continued to expand. Zinc alloy die casting parts companies, the increasing demand for lightweight vehicles has provided a broad range for the development of the die casting industry. 

Zinc Alloy Die Cast Part

Zinc Alloy Die Cast Part

Causes and improvement measures of shrinkage in Zinc Alloy Die Cast Part
Shrinkage cavity:
Shrinkage refers to irregularly shaped holes at the thick section of the die casting, and the inner wall of the hole is rough. It can even cause a local honeycomb structure in the die casting, which affects the strength of the casting. Product processing face hole exposed. The outer surface of the die-cast zinc alloy product has a quite dense structure, and some small holes will appear inside the workpiece due to the shrinkage phenomenon. If the processing volume exceeds the thickness of the dense layer, the holes will increase significantly.
During the die-casting process, the zinc liquid starts to solidify after it is pressed into the cavity and filled with the cavity. Due to the low temperature of Die Casting Mould Components and water cooling, the zinc alloy is die-cast. The zinc liquid starts to solidify from the surface in contact with the mold. At the outermost layer, a hard shell is formed first, and the zinc alloy die-casting company gradually solidifies inward. Zinc solution gradually shrinks with decreasing temperature, but the outer surface of the casting has formed a sealed hard shell, so as the zinc solution gradually solidifies, some hollow spaces will be formed at the final solidified position, that is, shrinkage cavity. Excessive wall thickness results in a slow internal cooling and solidification rate. After the liquid metal fills the cavity, it cannot be replenished in the shrinking process, which is likely to occur on uneven thickness castings.
The method of eliminating shrinkage can be achieved by reducing the wall thickness of the area where the shrinkage is located, so that it can solidify quickly and uniformly, or by optimizing the structure of the casting and mold. Sometimes due to the function and structure of a certain area, the wall thickness cannot be reduced. You can consider increasing the depth of the prefabricated hole in the casting to change the processing area. From a process point of view, add cooling water channels to the molds in this area, strengthen the cooling, and accelerate the solidification speed of the zinc liquid to reduce the volume of shrinkage holes. It can increase pressure to increase the density of the tissue. 
It cannot be eliminated by 100%, it can only be reduced or transferred, and sometimes it is only a problem of shrinkage in processing.