NADCA EC-515 Die Casting Defects Course Review, Basics for controlling die casting defects - By Dr. Steve Midson
- Die Casting Sinks (surface depressions) are a form of shrink porosity
- A sink forms when the shrink porosity is close to the surface, and as it cools it pulls the thin skin on the die surface in towards itself
- The shrink porosity is close to the surface because the surface of the casting is the hottest point in that area of the casting
- Eventually, the casting solidifies with the sink in the surface
- The clue that the spot is getting hot and that a sink might form is when the surface of the casting starts to get rough (or frosty in appearance)
- The operator should notice this condition, and start to spray and/or adjust cooling line flow
- What is needed is a change in temperature balance between the hot and cold areas
(Thanks to All About Metallurgy for posting this PDF. We'll cover other aspects of die casting defect control by the proper use of die casting lubricants from the course in upcoming blog posts)
(If you liked this article you might also like this post on, "Die Casting Defects")
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