Delrin, Teflon or Other for sliding surface

[Dennis6086]

Does anyone have a recommendation for a low friction material for use in a gravity fed cardboard box delivery system? Delin and Teflon come to mind, but there are probably other materials.

I envision 1/2" sheets structurally supported from below, and cardboard boxes sliding down an incline. This is not for production use, and perhaps 10,000 boxes may slide down in its lifetime

These units will be used outdoors and exposed to the elements. I want to avoid mechanical rollers and wheels.

Thanks in advance!

Dennis

 

[insideman]

Are you sure you want to pay for 1/2 inch thick Teflon? How about sheets of UHMW polyethylene? Not 1/2 inch thick-This stuff is remarkably resistant to abrasion.

 

[petersn]

I agee with insideman regarding UMHW Polyethylene. Look at pricing of Polyethylene vs teflon or delrin. (note 'delrin' is the tradename for Dupont 'Acetal')

Once you look into cost of Polyethylene, you'll be compelled to make it work.

1. BEWARE of 'SAG' !! with any plastic system such as you are devising. I envision whatever plastic you choose to be mounted via screws to some sort of metal frame. Sag, otherwise technically known as 'creep' (meaning deformation over time') WILL HAPPEN. You mention 'sheets', but I think you should think plastic 'rails' on metal frame. (All plastic is subject to creep).

2. Be sure to use UV (ultraviolet) resistant with any plastic you use as you mentioned that this is an outside installation.

Good Luck! - petersn

 

[Dennis6086]

Insideman and Petersn,

Thanks for the quick replies. I am not tied to the 1/2" thick sheets, and did not consider the creep issue. I do like the plastic rail on supporting framework idea.

Any ideas on coefficient of friction of UMHW Polysthylene?

Thanks again!

Dennis

 

[petersn]

Dennis,

In my previous post, I recommended that you look into the cost of the materials you are considering.

Have you looked at cost? Please post what you found.

FYI, from somewhere on the web:
Coefficients.......
UMHWE = .12
ACETAL = .25
TEFLON = ????
NYLON = .35 (I was a little surprised not to see nylon on your original list of material candidates)
(Been a long time since physics 101, therefore I am not knowledgeable to interpret these numbers, nor can I vouch for their accuracy)

Don't forget UV stability!

 

[chaving]

Normaly the lower the cof (co-eficient of friction) value the more slippery the material.

Don't get confused between wear resistance and cof.

Acetal and PTFE (Teflon is also trade name) have very low wear resistance.... but in your application PP or PE should be fine

 

[dcb278]

Beware of using polyethylene in an outdoors app... it isn't very resistant to sunlight. 1/2" teflon is very expensive though. Solar exposure will naturally depend on where this is going to be used(and the service life). In Florida I wouldn't use something easy damaged by sunlight. In New York you could probably get away with it though.