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Drying aluminum chromated parts

 

We do finishing of aluminum: anodize, hard anodize & chromate conversion coatings.

For anodize & hardcoat anodize we have a drying tank oven at the end of the line to dry parts.

For chromate (aka Iridite / Alodine), we do not use the oven, as it discolors & damages the coating. We usually just use air hoses & manually dry the parts. This is usually OK, but when we get very busy with chromate, like now, this drying really takes a lot of time & hands.

Anyone have any methods or ideas to speed up the drying of chromated parts?

David A. Kraft
- Long Island City, New York

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It is good that you are not using the oven as temperatures over 60 °C damage the coating. However you could use the oven at a lower temp say 50 °C after the air blow just to speed things up.

Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England

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Here are a few ideas that you may be able to employ.

1) You may be able to use a series of air knives over the final rinse or you oven tank.

2) You can use your "tank oven" for chromate coatings as long as the temperature does not exceed 150 F. It is at this temperature when the Conversion Coatings begin to degredate.

3) It may be possible to aid the drying by heating the final rinse.

All of these items, or combinations of these, may be your solution depending on part configurations and fixturing mechanisms.

Best of Luck.

Ira Donovan, M.S.F.
Kansas City, Missouri