Solid film bolt lubricant spec

[preload]

Is any one here very good at reviewing the solid lubricant spec sheets? If yes, I can past couple of pages here and you can leave comments if we spec that out right or not, or if we need to do any changes.

All I request is to just review our spec sheet and tell me if we are doing it right.

 

[MintJulep]

A few suggestions:

You need to tell the coating supplier what the base material or materials will be.

The appearance requiremes of 5.2 are somewhat subjective. Consider adding photos of acceptable and non-acceptable appearance.

Presumably you will be buying lots of fasteners, do you really want to inspect 100% visually for coating defects? Define an inspection sampling plan.

Define the mating nut for the friction test.

I don't believe that it is correct to list all thread fit classes as an inspection criteria. Pick the one you need. The plater will need to know the thread fit class of the fastener to be plated.

The cure test sounds very specfic, perhaps only appropriate to a single supplier?

 

[israelkk]

Why do not just specify MIL-PRF-46010F for the coating freely available at

http://assist.daps.dla.mil/quicksearch/.

 

[CoryPad]

My comments echo those of MintJulep and israelkk.


Section 5.3 obviously limits the material to something specific - do you really want to do that? If you have the appropriate performance requirements, do you care about lubricant composition/manufacturer?

MIL-PFR-46010 is an existing specification - will it not meet your needs? If it does, then let the US Government handle publication, revision, etc. and then you can concentrate on building quality products.

Small error with 5.4.1 - micron is not an acceptable substitute for micrometer.



Regards,

Cory

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

 

[preload]

Mintjulep,

the spec is for just solif film lubricants not for a particluar fastener. It should go for all types of fits. So we specified all the fits.

 

[MintJulep]

Preload,

You will not be purchasing only a solid film lube will you?

You will be purchasing a fastener that has the solid film lube applied to it. The applicator needs to know what the substrate is. FOr example, he may be able to meet your adhesion requirements for a steel substrate, but not stainless steel or brass.

No single fastener can simultaniously meet the dimentional requirements of fit classes 1, 2 and 3. The application of a film to any given fastener may changes its fit class. Again, the plater will need to know what he is starting with.

 

[israelkk]

preload

If I was writing the spec I would specify the coated bolts to conform to the appropriate spec (ASTM. MS, NAS etc.) where all dimensions will be checked after all coatings and treatments. The coating will be per MIL-PRF-46010F 8-13 micrometer thick.

MintJulep

MIL-PRF-46010F as far as I recall doesn't differentiate between the various metals. For adhesion is asks for 220 mesh aluminum oxide grits blast before applying the solid film lubricant. In the case of bolts there may be a problem with corrosion if the bolt is not made of corrosion resistant alloy. In this case the solid film lubricant should be applied on top of a plated bolt. In this case the aluminum oxide blast should be omitted. The solution is to use a surface treatment to the coated bolt that will create a porous substrate for the solid film. For example, if the bolt is usually coated by cadmium or zinc then use a phosphate treatment to the cadmium or zinc instead of the chromate treatment.

 

[arto]

How about just call for Dacromet or Geomet:

http://www.dacromet.com/hcoat.htm

http://www.geomet.net/coatings.htm

 

[israelkk]

arto

The Dacromet and Geomet are cured at 315 Centigrade this limits the use of high strength bolts with are tempered much below 315 Centigrade.

 

[CoryPad]

Plus, if the fastener is corrosion resistant by itself, why pay for a zinc-based galvanic protection coating when all you want is the friction-modified topcoat?

Regards,

Cory

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

 

[preload]

Thanks a lot for all your inputs.