Oil Filled Nylon 2

[wfo74]

I am considering using an oil and MoS2 filled nylon (such as Nylatron GSM Blue) for a sliding "puck" in a variable pulley system.

This part will need to slide agains some aluminum ramps to actuate the gizmo.

My concerns are that the oil in the nylon will attract contaminants, as the pulleys will be operated in a "dirty" environment.

Anyone have knowledge or experience with using such a material in a dirty environment?

Thanks,

Jonny

 

[ornerynorsk]

The only oil-filled nylons I have used are dry in-hand, have not seen it where they exhibit seepage. Possibly under high temps?

 

[wfo74]

Thank you Ornery.

We will not see any high temps.

My experience with oilite bronze bearings are that they do indeed "seep". That is my concern with the nylon as well, as the (oilite) seepage attracts and hold contaminants.

Anyone else have any experience?

Jonny

 

[btrueblood]

wfo,

Yes, I've seen "seepage", or at least crud build-up (mixed dirt, oil, and possibly plastic wear residue) on rotary bushings of oil+MoS2-filled nylons. Not as bad as the oilite (never saw a film/bead of oil during early running), but then we didn't run the nylon bushings as long, they didn't hold up well under the loads and temp's. we were putting on them.

 

[wfo74]

Thanks guys,

Does anyone know the mix of this stuff?

Grey Nylatron looks like 2% MoS2, I would think that would stay the same, and the oil would somehow be added to that, but can't find any reference. Anyone know how much oil & moly is in the mix?

I can find no other manufacturer than Quadrant, maybe they still have a patent.

Looks like we are going to look for some prototypes made from this product, will keep everyone posted on the results.

Thanks a bunch,

Jonny

 

[HDS]

http://www.castnylon.com/premium.html

 

[wfo74]

This project has taken a puzzling turn!

I spoke with the Quadrant people about purchasing the GSM Blue material for use in our injection molding facility.

They declined to provide the material, maintaining that they do not provide material to consumers, only finished product.

So I called them on it, and asked for Quadrant to quote the part itself. They came back "no quote", with the explanation that the part was too small.

Yet, they still will not provide the material to use for our use.

Can anyone make heads or tails out of this? Is there another manufacturer?

????????????

Jonny

 

[ornerynorsk]

Stanyl ???

 

[patprimmer]

Nylotron is a proprietary mix. I very much doubt that it can be patented as various lubricants have been mixed with various plastics for many years, so adjusting the exact mix or lubricant formulation woud not pass an innovation test.

As far as I know, the manufacturer is a producer of standard semi finished stock. Making parts or compounds for sale is not their business.

It is quite easy but bit expensive to determine the MoS2 and oil contents by chemical analysis, but his should not be necessary.

Many nylon manufacturers offer friction modified grades of nylon or high bearing performance grades. I would try DuPont, BASF, Ticona, Solutia, UBE, Toray or whoever else you can find on the net for nylon 6.6 or DSM for nylons 4.6 or 6.6. The best bearing grades of nylo 6.6 is graphite and MoS2 filled. The graphite for lubrication and the MoS2 for nucleation to provide a surface with a highly crystallised fine crystal structure. Nylon 4.6 is so crystalline it need no further nucleation.

Companies like RTP, DSM and LNP (now Sabic I think) have specialised materials for bearing applications and alo a lot of data on their performance with explanations of how and why.

A company I am involved with also makes custom nylon compounds including heavily bronze filled grades that have some excellent bearing properties. They are Duromer.

http://www.duromer.com

Regards
Pat
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[btrueblood]

Pat,

The MoS2 doesn't provide any lubrication in nylon?

 

[patprimmer]

Btrue.

No it acts a a very efficient nucleating agent. The graphite powder does the lubricating. Wilson Fiberfill/Akzo/DSM @ Evansville Indiana and LNP/GE/Sabic both published some excellent data on this. I expect RTP, which was started up when staff from Wilson Fiberfill decided to go it alone when Akzo took over, also publish the same data.

You can replace the MoS2 in the formulation with rutile TiO2 and get the same result with white rather than black colour. Of course if you still include the graphite you end up grey.

Regards
Pat
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[wfo74]

Thank you guys, thank you Pat,

As with most things, the more I learn, the more I realize how much I don't know.

No lubricity inherent with the MoS2 eh? Never would have thought that.

What we are looking for is the most slippery material we can find, while still retaining good mechanical properties. Heat is not an issue, shouldn't see more than 250F or so.

Very important, however, is that we are able to actually obtain the material!!!! No good if we can't get it!

Jonny

 

[btrueblood]

Learned me something new, thanks Pat.

 

[Demon3]

A star for Pat. Great info, notes taken.

If you want lubricious material don't forget UHMWPE and PTFE depending on what other demands are on it.

Chris DeArmitt

"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill

 

[patprimmer]

I should have added that although the MoS2 does not itself improve bearing properties, the resultant high crystallinity is what improves the performance.

Chris is correct. Why use nylon if the temperature rating is not required. UHMWPE or PTFE might work. Also Acetal or PET might work. It depends on what balance of properties you really need. Remember bearings do generate their own heat and at high loads or speeds it can be considerable. Also soft materials take a set under load, so even if the co-efficient of friction is low, the might have a high start up friction after a long stop.

Regards
Pat
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[cpretty]

Two materials that are a possibility are:

PETP - Good friction coefficient, and very good creep resistance. Downside is that it is a little brittle, so not good in large impacts. It's usually pretty easy to get hold of. There is a lubricated grade available

Torlon - High end material that gives good friction coefficient and exceptional strength. Pretty pricy and is sometimes a challenge to find, but it gets a lot of use in the marine industry for plastic ball and roller bearings.

We investigated both of these for a project that had a problem with creep in UHMWPE. PETP was good for a sliding pad bearing and handled high pressures and heat generation. Torlon was abandoned due to cost issues

 

[Pud]

MoS2 filled nylon is very, very difficult to dry. The MoS2 is extremely hygroscopic and is very reluctant to let go the water. At least 12 hrs @ 80C in a vacuum dryer.

Harry

http://www.tynevalleyplastics.co.uk

 

[patprimmer]

But Harry, the silvery glimmer on the very dark grey mouldings looks so pretty.

Seriously Harry is correct, MoS2 makes the nylon somewhat harder to dry.

Regards
Pat
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