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Need to keep an ungalvanized area on parts
Dear Sir/Madam
I am working for Spanish Solar System Supplier at the moment.There are some parts.The people say that,"there souldn't be galvanizing here". I have painted these parts for obtaining ungalvanized parts. As I know that,polymer based materials are inreactive for HDG. However, I saw some parts were galvanized locally. How can I prevent this situation? Are there any special chemicals and/or materials for not coating? Can you suggest anything?
Thanks...
Kindly regards
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Hakan Esen, Material Engineer(BSc.) |
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I have tried for years to find something to "mask" galvanizing - without reliable success.
In hot rolled steel, where there is plenty of millscale present, its possible to paint with a solvent based paint, and this prevents the acid cleaning the millscale. Where the steel isn't free of oxides, it doesn't galvanize. So where you paint, doesn't galvanize.
But this isn't 100% reliable.
Where the steel is very rusty, its a similar thing. Paint prevents cleaning which prevents galvanizing. Again NOT 100%.
Where the steel is not rusty and has no millscale (like fresh cold rolled for example), its nearly impossible.
There are a whole range of proprietary branded masking systems. I have not found a reliable one.
If you find a reliable technique, let us all know!
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Geoff Crowley |
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I don't know but copper plating works fine as a stop-off barrier in carburizing. Maybe someone else knows if it works as masking for galvanization too.
Guillermo MarrufoMonterrey, NL, Mexico
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Sirs:
Copper plating does not work.
The information on masking that you seek is on pages 91-94 in:
"INTERGALVA 76" Edited Proceedings 11th International Galvanizing Conference, Madrid 1976, Edited by the Zinc Development Association,
34 Berkeley Square, London W1X 6AJ, Published by PORTCULLIS PRESS LTD., Queensway House, 2 Queensway, Redhill, Surrey RH1 1QS.
Likely you can get a copy of this article from the Zinc Development Association or by interlibrary loan from a large, or university library.
Regards,
- Hot Springs, South Dakota
March 24, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
I am using 304 SS as a slide bed for a conveyour. The outer portions of the conveyour structure is mild steel and is what we want to galvanize. The question: Is there anything that can coat the SS so it will not be galvanized in the process?
Steve CampbellProduct Designer - Knoxville Tennessee
April 14, 2011
The American Galvanizer's Association (galvanizeit.org) recently completed a test of about 16 different masking substances, from proprietary products to RTV silicone and duct tape. I am sure they will provide you this report if you ask. Most of the masking substances work at least somewhat; many can be hard to remove (paints and duct tape). At the plant where I work we apply a proprietary masking compound when requested by customers, for a charge that varies by how much time and material in involved. Use of masking materials always involves some extra cleanup.
The best solution is to design your product so that stainless and other parts you don't want zinc on are added to the assembly after the galvanizing. Otherwise talk to your local galvanizer and ask what they recommend. Most galvanizers will help you out on this.
- Seattle, Washington, USA