heat sink aluminium extrusion.How to solve the problem of black spots on the surface of die castings

　　It is highly likely that it is the formation of silica or alumina, which react in the air and then form black spots. The solution to this is to use fresh aluminum ingots, which are suitable for industrial use and have a clear trend in material use, decorative effects, and price costs. Another reason may be that too much release agent has been used or the organic content of the release agent is too high. Under the high-temperature action of hot melt aluminum, some organic substances are reduced to carbon elements, while others are decomposed into organic macromolecular polymers. When the die casting is formed, carbon molecules react with the polymer, causing black spots to form on the surface of the die casting. This can be replaced with another release agent or reduced by spraying the release agent. Finally, the black spots on the surface of the casting can be removed by grinding, rubber head electric tool polishing, or manual fine sanding.

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