Polytetrafluoroethylene vs Polyoxymethylene

[theoldwizard1]

a.k.a. POM vs PTFE
a.k.a. Delrin vs Teflon

I am designing something that will have a high load, flat, sliding surface. While the load will be high (>100 psi), the "speed" that the surfaces traverse are very slow. It will be exposed to the "elements", including road salt.

Which is better ?

 

[PCustoms]

100psi without telling anything related to size really doesn't tell the load...

 

[LopezBart]

You might also consider UHMW for this application.... https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene

 

[theoldwizard1]

100psi without telling anything related to size really doesn't tell the load...

Because I don't know the load !

It is a 8' wide slide out for an RV. Most of the weight will be carried on a Doing any kind of rollers/wheels would be difficult. I want to know if the friction and wear (with little or no lube) is "reasonable" for these.

Most of the weight will be carried on

 

[jack stand]

You might also consider UHMW for this application.... https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene

That's what I was thinking also, but I don't know chit about the different plastics. A buddy was building a hot rod and he put a uhmw strip between the plys of the leaf springs to improve the ride.

 

[PCustoms]

Because I don't know the load !

Then how do you know it's got 100psi?

Use uhmwpe

 

[LopezBart]

Here's a basic article on bearing plastics....

Engineered polymers – not your everyday plastics

Lightweight, quiet, and low-maintenance, polymer parts might be just what a machine needs.

www.machinedesign.com

 

[MoonRise]

PTFE is slippery, but not all that strong.

POM is a little stronger, but is brittle (to some extent).

UHMWPE (trade name TIVAR) is pretty strong (for a plastic) and pretty crack resistant and pretty abrasion resistant. Check into this one as a possible choice for your slides.

 

[4xdog]

I'd be more likely to go with acetal (Delrin) or UHMWPE. Probably the acetal.

PTFE has super-low surface energy -- the reason almost nothing sticks -- but I believe its coefficient of friction, the engineering property that seems most appropriate to what you've described of your application, is not as low as Delrin acetal.

What materials are sliding against what? That makes a difference too.

 

[tool_scrounge]

Money no object, I would be looking at

Turcite B Slydway​

 

[36truck]

UHMW Is very durable will hold a good load is slippery. I used this as a dump box liner. It took big chunks of concrete dumped on it & then dumped out. Lots of loads of gravel & dirt. It is not that expensive.It comes in many thicknesses from 1/8 up. It can be cut with a table saw drilled easily.

 

[tom in nh]

How about PEEK ?

 

[LopezBart]

UHMW Is very durable will hold a good load is slippery. I used this as a dump box liner. It took big chunks of concrete dumped on it & then dumped out. Lots of loads of gravel & dirt. It is not that expensive.It comes in many thicknesses from 1/8 up. It can be cut with a table saw drilled easily.

Yup... it's used for bearings for rudder posts on boats, rub rails on boats/docks/piers of all sizes. Tough stuff.

UHMW Fender

Catalog of UHMW Fender: Main Catalog Page: Marine Fender

www.pacificmarine.net

 

[Firebrick43]

Teflon needs a prepared surface to work with. If the surface of what it’s riding on is too smooth it has high stiction. A correct surface would be something like bead blasted then chrome plated steel.

UHMW would be my choice for a flat slider. Lower coefficient of friction. Good environmental resistance

POM/acetal is better for rotating bearing or something with high point loads and tighter tolerances as its more stable and less creep. But it’s not very Uv resistant.

 

[WoodsTruck]

You mentioned road salt in your first post.
What are the chances you will eventually get road grime built up on the sliding surfaces?

 

[danielbuck]

Yup... it's used for bearings for rudder posts on boats, rub rails on boats/docks/piers of all sizes. Tough stuff.

UHMW Fender

Catalog of UHMW Fender: Main Catalog Page: Marine Fender

www.pacificmarine.net

offroad competition folks use sheets of UHMW on their belly skid plates and such, to help the vehicle slide over rocks. they take alot of abuse!

 

[RPH]

Teflon is too soft. It will cold flow under pressure. Take a piece of Teflon squeeze it in a vice. Come back 24 hours later and it will be much thinner where squeezed. We used virgin Teflon only as an electrical insulator. Delvin, uhmw, nylon, and some other plastics are built for light bearing use.

 

[john.k]

Get some specialized plastic bearing strip made for sliding locations ,like crane booms and conveyor tracks

 

[GCS]

“Slick 50” contained PTFE
It‘s NOT an engine additive, it’s an engine Treatment!