plating, anodizing, & finishing Q&As since 1989
Since a few month we are plating small steel parts with 12 µm EN. Since two weeks we have problems: After less than 0,3 MTO the EN layer becomes blackish ore anthracite. We didn't change anything. We repeated that "game" for four times, but it's always the same - it begins with very bright EN and after a few charges it turns to anthracite coulored layers. Can anybody give me a hint?Klaus-Martin Hentrich
- Velbert, Germany
You are probably contaminating your tank with copper or cadmium or aluminum or gross amounts of iron.
Drag in is my first guess. This is probably a shared line
The EN tank might be close to a chrome tank where the hood is shut off when not in operation or is inadequate.
At the price of nickel these days, it deserves its own preprocess line.James Watts
- Navarre, Florida
It sounds as if you are shocking the solution by making adds which are too large. You might try making your adds more often in smaller quantities.Phil Pace
- Tulsa, Oklahoma
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