Plastic Plain Bearings 3

[nornrich]

All,

What is the most cost effective material for a simple plain roller bearing? I have looked at UHMW Polyethylene, but I think there is a better plastic out there at a lower cost. The RPMs and load are very low.

Regards,

Rich.....

Richard Nornhold, PE

 

[MikeHalloran]

Plain bearings are not roller bearings. I'll assume you know that, and you're seeking a roller with integral bearing.

UHMW is difficult to machine accurately. Its low friction coefficient and wear resistance make for decent plain bearings, especially if a little liquid is available.

Delrin is not terribly expensive, has good strength and tribological qualities, and is very easy to machine.

It would help to know some numbers, like actual load and speed, and the dimensions of the rollers you have already tried.



Mike Halloran
Pembroke Pines, FL, USA

 

[unclesyd]

Adding a little to the above post the two materials that I've seen used most in roller bearings are Delrin and Ryton. Delrin is the most prominent material especially for marine use.

 

[nornrich]

MikeHalloran,

I had meant to say a plain bearing for rotary application. Sorry for the confusion.

Regards,

Rich.....

Richard Nornhold, PE

 

[nornrich]

MikeHalloran,

The loading is less then fifty pounds and the speed is less then 25 RPM.

Regards,

Rich......

Richard Nornhold, PE

 

[unclesyd]

Delrin as mentioned above is good choice.

If you can comeback with a little more information about size and environment there should be some other choices.

 

[nornrich]

unclesyd,

The OD is 3/4" and the ID is 13/64". The shaft is regular Hot Rolled Steel and is 3/16" in Diameter. Environment is dry with no moisture and/or lubrication.

Regards,

Rich.....

Richard Nornhold, PE

 

[nornrich]

unclesyd,

Also I'm looking for something that can be injection molded.

Regards,

Rich.....

Richard Nornhold, PE

 

[unclesyd]

We are short a little physical information to pin down a specific material. I would give Nylon a serious look. It is among the least expensive and easy to mold and readily available.

Give the Vydyne Technical Support people a call.

http://www.vydyne.com/pages/product_info.asp

Are you intending to mold the component in house?

 

[MikeHalloran]

Delrin, machined from solid rounds, would probably be a good choice for small quantities, unless the shaft is very rough.

Molded Delrin with that kind of wall will sink badly, so the molded piece would need to be relieved on the faces, into two annular rings and a diaphragm between them. Which, except for the material, describes a kind of bearing with integral spacer bushing that I thought was already produced by Thomson.

Delrin and nylon are both available in economical stock bearing forms, too. See nyliner.com for a start.





Mike Halloran
Pembroke Pines, FL, USA

 

[nornrich]

Thanks MikeHalloran & unclesyd. Your information is very helpful. I will look at both Delrin and Nylon as possible materials for this application. The bearing will probably be running at a quantity of 50k - 60k per year. The Bearing isn't solid it is ringed with ribs between the two rings, so shrinkage is kept to a minimum.

Just as a side note, it is great having a community of mentors & peers to be able to reach out for guidance and wisdsom. You both represent what it means to be master engineers, passing on your knowledge to us journeymen and apprentice engineers. Thanks for your time and advice.

Regards,

Rich.....

Richard Nornhold, PE

 

[MikeHalloran]

In the geometry we have been discussing, ribs distort the rings. If you don't need them to take moment loads off the diaphragm, you're better off without them.



Mike Halloran
Pembroke Pines, FL, USA

 

[Philrock]

Turcite, made by Busak & Shamban, is an excellent bearing material. Available as bar stock and finished bearings in many sizes. Don't know if it's available as molding compound.

http://www.busakshamban.us/prod_global.htm?pid=303

Igus makes quite a few different bearing compounds. Available as finished bearings in many sizes. Don't know if it's available as bar stock or molding compound.

http://www.igus.com/

 

[diamondjim]

I think we used Nylon 66 for ball
spacers awhile back. We are using
HDPE now for them and they seem
to wear well in that type of application.
Both were injection molded.

 

[Pud]

Ticona produce a booklet "Designing Plain Bearings in Engineering Plastics" or similar such title. Other manufacturers too I guess.

The Ticona website is a bit tedious to register but it's probably got all you need in it (the booklet, that is).


Rgds


Harry

 

[FACS]

Id say that plain nylon is the most cost effective.... betting on a plain bearing and a plain application.

Charlie

http://www.facsco.com

 

[bentwings1]

here is a place with lots of plastic bearings plus eng charts

http://www.igus.com/

99 Dodge CTD dually.

 

[JimCasey]

Nobody has mentioned Acetal yet. Almost universally used as shaft bearings for butterfly valves. Nice stability, easy to machine, inexpensive, injection moldable. It's the same stuff screwdrive handles are made from. Eastman tradename: Tenite.

 

[JimCasey]

OOPS! My Bad. Delrin is an acetal. I found a pretty cool reference sheet:

http://www.qbcbearings.com/B605/qbctech32.htm

 

[Saheb]

from my experiment in this field,,the nilon 66 (poly amide) is the best plastic material for the bearings it is life is very very long and the wear is very low even in high speed aplication and it is easy in molding specialy the low density type

best regard

Saheb
Babylon