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maz		 what is rat tail in casting defects? View All
i need to know the definition and what it is all about...need urgent,thank you!!!
16 years ago - 5 months left to answer. - 1 response - Report Abuse
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Meridian
 As molten metal runs over the surface of a green sand mold, moisture in the sand is converted to steam that permeates between the sand grains. When the steam reaches a point in the mold where the sand temperature is less than 212F (100C), it re-condenses, creating a wet layer. This wet layer is weaker than the normal green sand or the hot, dry sand layer directly beneath the metal. As the hot sand expands, the wet layer shears to allow the expansion. The small ridge of sand that extends into the mold cavity as a result of the expansion can create a line on the surface of the casting called a rattail

16 years ago

Source: http://www.allbusiness.com/manufacturing/fabricated-metal-product-manufacturing/814505-1.html


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