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How to eliminate colored spots on the surface of cast copper parts

Update:08 Nov 2019

Cast copper pieces with colored spots Other names: oil […]

Cast copper pieces with colored spots

Other names: oil spots, black spots.

Features: Spots on the surface of the cast copper that differ from the base metal are typically formed from the coating carbide.

Causes 1. The paint is not pure or used too much. 2. The coating contains too much graphite.

Exclusion measures

1. The paint should be thin and uniform, and should not be piled up. It should be blown away with compressed air. 2. Reduce the graphite content in the coating or use a graphite-free water-based coating.

Cast copper piece

Characteristics: During the filling process, due to the mold temperature or the temperature of the alloy liquid is too low, a fine pitted distribution area formed on the surface of the cast copper part under the condition of under-pressure is obtained.

Causes 1. The metal is dispersed into dense droplets during filling, and the wall is impacted at high speed. 2. The thickness of the ingate is too small.

Exclusion measures

1. Design the casting system correctly to avoid splashing of molten metal, improve exhaust conditions, avoid excessive flow of gas into the flow, reduce the speed of the gate and increase the temperature of the mold. 2. Adjust the thickness of the ingate properly.