Dry lubrication and corrosion prevention of ACME screw in dusty location

[muddybiker]

Hello everyone,

Thanks for taking the time to look at my thread. I'm new to posting but have been reading threads here for a while.

I'm designing an acme screw lifting device in a warm and dusty location. By warm I mean 80-140 F in an industrial setting with some coal and dirt dust present. It is a dry area typically but we expect it to be washed with water several times per year. The acme screw will be used very infrequently (say twice per year) under low to moderate load (ie the threads and acme nut are not seeing anywhere near their maximum theoretical load, in theory anyway). I would like to find some sort of lubricant and/or corrosion inhibitor to use on the threads that will prevent rusting, and provide some lubrication as well. Since the screw is not heavily loaded and is used rarely, I think the corrosion prevention is more important. The lubricant needs to be dry enough to not collect dust. The screw and nut are both steel; need to keep them from rusting together as well.

DuPont™ Teflon™ Non-Stick Dry-Film Lubricant appears to have many of the characteristics I am looking for. LPS 3 Premier Rust Inhibitor looks decent too, although I don't know if the "waxy" film will be dry enough to prevent dust collection. Some dry Teflon mountain bike chain lubes come to mind as well.

Does anybody have any ideas or recommendations? I appreciate any and all tips!

Thanks,
muddybiker

 

[MintJulep]

http://boeshield.com/

 

[dhengr]

Muddybiker:
“With some coal and dirt dust present” and “we expect it to be washed with water several times per year”.... means the threads will mostly be full of coal dust, and subject to rust when that dust gets wet or damp. I would want to use a dry lub, some graphite maybe, although some coals are oily enough to probably have some lubricating value, but with an abrasive component too. I’d want to cover the whole screw and nut, to keep the dust out. Maybe some sort of a bellows type cover. Then also apply some sort of a set of acme screw thread plows and brushes at the top and bottom of the nut to clear the thread when you activate the system. For that matter, if you were only going to use it once or twice a year, you could literally remove a gasketted cover as part of that operation. If all you are doing is lifting something, why not bring in a 5 ton jack when you need it? If you are adjusting something in height or belt tension or some such, and then holding it in place with the nut, I guess that’s another matter.

 

[TVP]

There are a number of lead screw manufacturers that offer bonded dry film lubricant coatings as an option. Typically epoxy or phenolic resin with PTFE particles suspended in it. Others have MoS2 or graphite.

 

[bithkits]

Some random ideas:

Make the screw from a polymer. Perhaps Delrin/acetal?

Use cast or sintered metal that has lubrication built into the compound during manufacturing?

Use a different mechanism that may be enclosed in a gearbox?



Mechatronics Engineer from South Africa.

 

[bithkits]

Also,

http://www.rocol.com/products/tufgear-spray-aerosol-open-gear

Mechatronics Engineer from South Africa.

 

[KENAT]

DLC? Seems a bit exotic though.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[jbeckhou]

I would suggest either QPQ, Xylan, or Phosphate coatings.

Petrotrim Services

http://www.petrotrim.com

 

[Cockroach]

Liquid nitrate the pieces, both nut and bolt and have the oil removed after bathing. You can assemble these pieces in the dry state. The process removes free iron from the surface of the metal to a depth of about 1/128 inches. You should get a hardness around HRc 45/50. Let the plant know that water quench is not acceptable during the liquid nitration process, you would get micro cracking in the roots of threading.

I do this all the time.

Regards,
Cockroach