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Letter 23066
Corrosion in rivet head
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Dear Sirs,
My Company manufactures parts for Automotive Air Conditioning
Systems (Compressor Clutches). I need to solve an issue raised by
final customer regarding steel rivets protection. Rivets are
protected against corrosion (Zinc+Iron plated, passivated in Black)
and, as an unused part, they can pass the Salt spray test 96h (even
200h) easily. What happens is, after rivets have been riveted, some
spots of the Rivet "head" loose the protection. How can we fight
this? Somebody proposed using "Electrolitic zinc plate, trivalent
chromate, leached and sealed". Can you explain what is this?
Thanks in advance.
Best regards,
José Teixeira
Pinto
- Lisboa, Portugal
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Mr Pinto,
The following may help.
1) The Zinc Iron Plated Rivets should be coated with a water
Soluble lacquer after being black passivated.
2) After the rivets have dried fully these must be left in storage
to cure for 24 to 30 hours and used only after curing.
3) If the the riveting operation imparts a hit on the head of the
rivet, chances of damage to the lacquer and Black passivate coat are
entirely possible.
Try a dirrerent riveting technique which essentially is a firm
squeeze rather than a strike. That is a press operation..
4) try using a NON SILVER based passivate followed by lacquer.The
color is not as shiny , but cosmetics are not an issue, whereas
Corossion protection and abuility to withstand riveting are the
issue.
Non Silver passivate films are a bit tougher after being fully
cured. And lacquerd.
Hope this helps.
Regards,
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