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Defect in aluminium castings causes black marks? [India]

I am working with a casting firm. We have faced a problem that we have supplied casting component to our customer they were ok at the time of dispatch, but when they reached customer end the casting have lost its shine and black patches or black marks are developed on the parts can you suggest me how tis happens if happened than what are the possible ways to remove these marks.
I will be thankful to you.

Ashutosh Mishra
quality engineer - Delhi, India
July 25, 2010

July 28, 2010

Ashutosh

If the castings are not adequately packaged, movement against cardboard or even paper can abrade the aluminum surface and produce such marks. Are you dispatching the parts across town, or across the country? Are the black patches on the bottom of the parts?

Willie Alexander
- Colorado Springs, Colorado

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