Polyurethane Rollers

[nornrich]

I am trying to determine the feasibility of replacing steel cam roller bearings with a Polyurethane coated steel wheel. The situation is as follows: We have a round steel drum that is not perfectly round and is unevenly riding on four steel cam roller bearings. I know the correct approach would be to correct the problem with the drum, but this is extremely costly and will take us out of production longer then we would like. The drum and the contents are around 8000 lbf of loading. The existing cam roller bearings are 6" in diameter and are mounted on a two inch shaft. I am thinking of using a 4" steel hub and coating it with 2" of a 90A Polyurethane. My thinking is that the Polyurethane would help take care of some of the uneven distribution of loading and provide beter wear characteristics then the existing steel on steel set up. Any thoughts on this matter would be appreciated.

Regards,

Rich....

Richard Nornhold, PE
ampdesign@earthlink.net

 

[GregLocock]

I agree, look up solid wheels or polyurethane tires in your catalog. We use them on the cradles for our yacht, make sure there is a mechanical retention, not just glue, between the tire and the wheel.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Pressed]

I had a similar situation but a different application and the urethane to metal condition is a work in progress to say the least. Plan to have back-ups waiting.

The size you are describing seems like a large follower that is designed to carry alot of force? Do you know what the force is, what is the follower width??

I went through several iterations of engineering plastic to solve my problem, which was mostly wear; finally settling on Uniroyal 1950A Urethane (95A). This was cast onto a tool steel wheel. The working force was around 1000 pounds and the surface speed was about what a man could push/pull a 2" bar. Yeah, I'm not sure what that is either; but you get the idea. This machine ran contantly and the key was the contact of the urethane to metal; which was the weak link of the whole thing.

If your load is high, make the thickness of your urethane 1/2" to 1" or thinner. Mine was about 1 1/2" thick which allowed for resurfacing. When the working force was applied there was no perceptable deformation of the urethane.

If your surface speed is fast then reducing the urethane thickness will increase the surface area contact between the metal and urethane. You could also rough up the steel to increase bond strength.

Test a chunk of urethane of different thicknesses before making a wheel. Hope this helps. Good luck.

_______________________________________
Feeling frisky.........

http://www.tailofthedragon.com

 

[MikeHalloran]

Before going full custom, check that there is not a standard heavy duty caster wheel available in the size and load rating you need.

For instance, from mcmaster.com,
5010T21 caster assembly, fixed $104.57 each
5010T333 replacement wheel



Mike Halloran
Pembroke Pines, FL, USA

 

[nornrich]

MikeHalloran,

Thanks. I did check McMaster before looking to a custom design. They didn't have the geometry that I needed. I need a 3" wide roller and in 6" I was only able to find a 2 1/2" wheel. Plus there are special requirements for bore and keyway.

Regards,

Rich.....

Richard Nornhold, PE
ampdesign@earthlink.net

 

[DDRSS10]

I have some experience with urethane bonded to steel. The key to keeping the two togather is a mechanical retainer such as a back cut slot, or several, in the od of the shaft. There is a company called IMR, Industrial Molded Rubber, that does bonding/lagging of this sort. Try them, they could probably help.

http://www.imr-inc.com

Nick

"Speed costs money boys, how fast do you want to go?"