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Shrinkage defects in custom metal casting molds or molding process

26 Jul 2017 - custom metal casting,metal casting molds,molding process

Shrinkage defects in custom metal casting molds or molding process

A custom metal casting molds defect is an undesired irregularity in a metal casting process. Some defects can be tolerated while others can be repaired, otherwise they must be eliminated. They are broken down into five main categories: gas porosity, shrinkage defects, mold material defectspouring metal defects, and metallurgical defects


There are many types of defects which result from many different causes. Some of the solutions to certain defects can be the cause for another type of defect. The following defects can occur in sand castings. Most of these also occur in other casting molding process.


Shrinkage defects in custom metal casting molds or molding process

Shrinkage defects can occur when standard feed metal is not available to compensate for shrinkage as the thick metal solidifies. Shrinkage defects can be split into two different types: open shrinkage defects and closed shrinkage defects. Open shrinkage defects are open to the atmosphere, therefore as the shrinkage cavity forms air compensates. There are two types of open air defects: pipes and caved surfaces. Pipes form at the surface of the casting and burrow into the casting, while caved surfaces are shallow cavities that form across the surface of the casting.


Closed shrinkage defects, also known as shrinkage porosity, are defects that form within the casting. Isolated pools of liquid form inside solidified metal, which are called hot spots. The shrinkage defect usually forms at the top of the hot spots. They require a nucleation point, so impurities and dissolved gas can induce closed shrinkage defects. The defects are broken up intomacroporosity and microporosity (or microshrinkage), where macroporosity can be seen by the naked eye and microporosity cannot.


Alpine Mold is a custom metal casting molds manufacturer, having specialized in metal casting molds or molding process for more than 25 years with good quality and pretty competitive price. Please contact us by kerry@alpinemold.com.

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