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Chromating and anodizing defects

2003

Case 1
Recently I had sent a batch of Al 2011 material to tumbling process after machining. After tumbling, I observed there is some residue penetration into the material (white colour). But residue was not able to be removed by the cleaning process, and then it was sent for Chromate Conversion Coating. But the result was not up to the expectation. The coating seem to be not uniform penetrate into the material. Obviously can see the aluminium surface in some area.

Case 2
Al 5083 was sent for clear anodizing. After treatment, it seem to have burning mark along the part.An evaluation was carry out by removing the burning mark and re-treat once. The same result was observed. Please advice. Thank You

Jonathan Sia
- Muar, Johor, Malaysia