Protection against corrosion - bearings 1

[roberto1brazil]

Hi all
Please, could someone help me with the following issue?
At my company we have the procedure of protecting bearings putting them inside VCI plastic bags with its proper sealing. Before putting them inside the VCI bags, they are protected with the product Turboprotec aerosol. For some reason (unknown) after some weeks, when the bearings had their VCI bags opened, it was verified that some little pits of corrosion were observed. Unfortunately, according to our norms such pits were enough to reject the bearings. Just for information, the bearings were storaged in a room without control of temperature and humidity. We intend to change the process of protecting the bearings as follows: Immerse the bearings in the chemical product Wadis and putting then inside a VCI bag with a double sealing (the proper one that is in the bag plus another one making use of a sealing machine.
Do you think that the new procedure will avoid the outbreak of corrosion in the bearings? A room with temperature and humidity controlled would be necessary? Is there another alternative method to apply?
Thanks for any hint that you can suggest.

 

[tbuelna]

roberto1brazil-

You've brought up a very under-appreciated subject: proper handling, cleaning and packaging procedures for precision components. The bearing surface corrosion you see can indeed be the result of humidity in the air trapped inside the sealed bag. It can also be the result of people handling the parts with bare hands, since perspiration on the skin surface is fairly low pH. There are even special cleaning solvents designed for removing fingerprints from metal surfaces.

Besides taking more care in how your steel bearing parts are packaged, I would also suggest reviewing the procedures you have for corrosion control during all of your manufacturing operations.

Here is a MIL-SPEC (MIL-DTL-197) for packaging of bearings. It might be a bit excessive for your application, but it gives some excellent guidance.

http://www.everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/download.php?spec=MIL-DTL-197L.037623.PDF

Hope that helps.
Terry

 

[mrfailure]

I have also seen the situation where protectant was applied but was not allowed to dry before sealing. Inherent moisture of the wet protectant then caused corrosion.

Aaron Tanzer

http://www.lehightesting.com

 

[roberto1brazil]

Thanks a lot for your attention. We are going to do a follow up of our process.

 

[TomDOT]

If you have good VCI bags, they're sealed and your parts aren't contaminated with salt and/or moisture - the VCI should be enough by itself.

Do you have an MSDS for the Turboprotec? The manufacturer's site I found online demanded a username and password to see the MSDS. Quite odd.

 

[roberto1brazil]

Hi!

I have not the MSDS in English. The MSDS available here at my company is in French. Anyway, I am attaching that document for your appreciation. If you have any doubt, please, let us know.
Thanks

 

[TomDOT]

Hm, mostly petroleum distillate. Not a very helpful MSDS. Sometimes they can give more insight.

My French isn't great, but at least I can puzzle through a fair amount of technical French.