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Corruption of NYLON LOCKS of the Self Clinching Nuts in the ALOCROM process

 

We have an aluminum sheet metal part with some PEM PL series self locking and self clinching nuts on it. We are going to send that part to Chemical Conversion Coating (Alocrom or Alodine 1200). We wonder about if the Nylon locks of the nuts become corrupted during the coating process?

Thanks,

Senel Canik
- Istanbul, TR, Turkey

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The answer to this may be try some and see with a torque test before and after. Alocrom will attack nylon, as nylon is linked by chemical bonds which are like the links in human flesh. So if the process will attack human flesh it will attack nylon. However the real world is sometimes different to the world in books. Nylon is attacked by electroless nickel plating yet we can use nylon masking screws - they get destroyed after several uses. What might be a bigger issue is what the nuts are made of and if they are coated. High tensile steel, zinc, cadmium are all not recommended to go into alocrom. Stainless would be best to go into the alocrom but a real no-no from the galvanic corrosion point of view. The parts could be masked so the nuts are not treated but the best way would be to add the nuts after the alocrom.

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

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WOOOHOOOOO! Another pooch pic..Gotta luv it! Hmmm..there really seems to be a correlation between metal finishing and dog lovers!

Marc Green
anodizer - Boise, Idaho

There are a great number of types of nylon, so it will depend. In general, nylon does not like acids or oxidizing agents (chrome) and does not really like hot caustic. SO, it probably is not a good idea, but you can always try a test panel or two to see. One thing that is quite probable - you will have staining around the nut from the run out of the trapped chemicals.

James Watts
- Navarre, Florida

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I agree that the bleedout problem is probably the biggest issue, but that said, hundreds of millions of plastic insert nuts are zinc plated and chromated every day, so there is a way around it.

  
Tom Pullizzi
Falls Township, Pennsylvania