Assembly lubricant for zinc plated bolts and nyloc nuts 5

[rattler]

I'm aware of the need to lubricate bolts on assembly to reduce the scatter on preload. Is there a particular lubricant type or viscosity recommended please?

Thanks

Rattler.

 

[CoryPad]

Ideally, you would have the lubricant integral with the coating. Here are some suppliers with good products:

Torque N Tension from Macdermid:

http://www.macindustrialproducts.com/Functional/Functional.htm#TNT

Magni 560 or 580 topcoats from Magni:

http://www.themagnigroup.com/products_500.asp

Deltacoll or Deltaseal from D[ö]rken:

http://www.doerkenusa.com/products.html

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[rattler]

Thanks Cory - I've never heard of these products before. However in this application I want to specify an assembly lubricant for use with standard "off the shelf" zinc plated bolts which we already have in stock. Is there a particular lubricant type or viscosity recommended please?

 

[MintJulep]

Regular old grease works, as does any of the anti-sieze compounds available. Oil is not as good.

If good control of preload is important to you in this application you should do your own tests to determine torque vs. preload relationship for whatever you specify. Then get the word out into the shop that using the right stuff is important, and explain why.

 

[CoryPad]

Rattler,

The products I mentioned are used in high-volume applications for automobiles. If you can't use the lubricant as a pre-applied type, I would try the Macdermid product shown above - I believe it is a simple immersion product, while the others are more complex polymers that require baking to cure the coating. All of this information is for high precision applications. If you can work with less precision, then simple grease, waxes, and oils will be satisfactory.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[yates]

It's a little unconventional in the fastener business, but my personal experience would lead me to use powdered graphite for zinc on nyloc applications. It has the advantage over grease and oil that, in service, it does not pick up dust to form an abrasive paste. Friction coefficients are about as low as with moly disulfide coatings.

 

[Screwman]

I would tend to stay away from plain grease as a thread lubricant, it tends to not hold up under the pressures seen on the thread flanks.
The anti-sieze products work well to prevent galling, but they tend to act more to generate a consistant friction factor rather than a drop in friction. We have had good experience using moly lube to reduce friction, but it is horribly messy and contaminates everything in the general area.

 

[nashjp]

Friction varies more at the underhead or nut bearing surface than in the threads. If you decide to use something like anitsieze or moly at the point of assembly be sure to have the lubricant applied to both the threads and the flat rotating surface.

Be cautious with electoplated zinc fasteners, the friction can drop so low that a "standard" torque can neck the fastener. Do a trial first and have your assemblers let you know if the sense the bolt was getting easier to turn or softening toward the end.