deteriorating rubber contact wheels

JDWARE

JDWARE

Joined
Nov 28, 2011
Messages
287
The 4" rubber contact/drive wheel on my KMG horizontal grinder is turning soft and falling apart. With only moderate pressure, my fingernail can dig out pieces of the softened rubber, from both the wide "contact" surface and the narrow surface exposed at the top of the aluminum hub. This is the second KMG supplied wheel to fail in this way after about five years.

I have other rubber contact wheels that have not deteriorated in this way - the small wheels for the horizontal grinder supplied by KMG about ten years ago; large and small rubber contact wheels from Bader that are 40 years old; and an AMK wheel that's about 4 years old. (The 40 year old Bader wheels have gotten hard, but are still usable)

KMG had this to say "........The rubber on your wheel is a natural product, and under some conditions (largely environmental) it can become devulcanized and degrade.The primary agents that cause rubber and plastics to deteriorate are radiation, high humidity, high temperature, oxygen and pollutant gases, and stress and other direct physical forces. It doesn't surprise me at all that two wheels have done the same thing in your shop -- same environmental conditions. Here in our shop we store our small wheels in a container that is treated to help preserve them............."

I do live in a sub-tropical climate about 20 km from the sea with high heat most of the year and high humidity during the rainy season.

I don't believe the degradation is due to use, or abuse. The direct drive motor is 1725 rpm max, run off a VFD at low speeds. I'm not a production shop. The only direct grinding I do on the contact wheel is final profiling of the inside surfaces of folder springs - no heavy grinding.

Has anyone else had a similar experience?

Saludos
J

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I had one about the same size that blew a chunk out alot bigger than your and made the wheel unusable. the rubber just under the surface was like a gummy worm. I do have high humidity in my shop 🤷‍♂️
 
My question about environment being the problem, are the other rubber wheels giving the same problem? Are they not exposed to the same environment conditions and use?
 
have a lot more time on my 2" wheels and never had a problem with those ?? 🤷‍♂️
 
What are the ozone levels where you live? It is natural rubber which "dry rotting" is ozone attacking it.

What are the storage conditions for them?
 
I think that's an issue with polyurethane... My poly wheels do that after a while.
 
REK Knives said:
I think that's an issue with polyurethane... My poly wheels do that after a while.
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But KMG is dura 95 natural rubber. I have one..

Does that make sense? I'm thinking it through but, idk.

I have no idea what that looks like exactly. It's not ozone. Oils?
 
My KMG wheel fell apart pretty badly too. It got sticky and you can poke your fingernail into it and it lost its structural integrity. I would think that if it were an environmental factor it would have been more on the surface and not all the way through. That and it was stored properly. While it's true that rubber can deteriorate from UV exposure, solvents and chemicals, and things like ozone, I think it was just a crappy job on the rubber.20180910_165156.jpg20180910_165222.jpg
 
guys i'm kind of surprised that no one here on B.F has ever looked into or posted about "re pouring rubber" onto or making "Contact wheels"..
im looking into it for myself ..and from what ive found , it does not look too bad , buy chemicals ,clean up old, pour new, clean up again , done
 
I wish KMG were more forthcoming with information. They claim that their wheels are "natural" rubber. But only the 4" drive/contact wheel is failing, not the small wheels. There is obviously something different in the composition or fabrication of the two types of wheels that KMG supplies.

When the first wheel failed five years ago, I thought that perhaps I had gotten some type of solvent, or oil, wax or WD40 on it while cleaning the steel work surfaces around the drive wheel. So I had been very careful not to get anything on this wheel. The failure seems to take place very quickly..... and at this point, the wheel is so sticky that it holds onto the back of the grinding belt so securely, that the motor won't turn!

My temporary fix has been to wrap the wheel with a couple layers 2" wide black electrical type tape.

Saludos
J
 
JDWARE said:
I wish KMG were more forthcoming with information. They claim that their wheels are "natural" rubber. But only the 4" drive/contact wheel is failing, not the small wheels. There is obviously something different in the composition or fabrication of the two types of wheels that KMG supplies.

When the first wheel failed five years ago, I thought that perhaps I had gotten some type of solvent, or oil, wax or WD40 on it while cleaning the steel work surfaces around the drive wheel. So I had been very careful not to get anything on this wheel. The failure seems to take place very quickly..... and at this point, the wheel is so sticky that it holds onto the back of the grinding belt so securely, that the motor won't turn!

My temporary fix has been to wrap the wheel with a couple layers 2" wide black electrical type tape.

Saludos
J
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There is clearly something wrong with that wheel and I would not use it. And if it is not an old wheel that has been abused, I feel like somebody owes you a new wheel.
 
I have the same problem with an 8" wheel from Beaumont. Probably about 10 years old, used gently and infrequently. As I recall it cost about $160. It was stored with care but my shop does get quite warm.
 
Nathan the Machinist said:
My KMG wheel fell apart pretty badly too. It got sticky and you can poke your fingernail into it and it lost its structural integrity. I would think that if it were an environmental factor it would have been more on the surface and not all the way through. That and it was stored properly. While it's true that rubber can deteriorate from UV exposure, solvents and chemicals, and things like ozone, I think it was just a crappy job on the rubber.View attachment 1933185View attachment 1933186
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I have these wheels (8 not 10) they said to me (mind you an "engineer" had to have me explain asking what the delta between two numbers was and thought A36 was 1018), said duro 90 not the duro 95 on the serrated wheel for surface grinding is used for these wheels. What does that mean exactly? Take your guess.

I store mine with VCIs which probably is incredibly stupid but I don't hollow grind shit anyway and would just buy another wheel.

polish avenger said:
Lost not only the wheel, but some perfectly good underwear.
Sent a pic and a note to KMG and I found their response to be a bit too cavalier for my liking.

-Mark
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Their house is a joke. I refuse to make contact with them. Not kidding either. A lawsuit was nearly filed. I don't recommend them.
 
Nathan the Machinist said:
There is clearly something wrong with that wheel and I would not use it. And if it is not an old wheel that has been abused, I feel like somebody owes you a new wheel.
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They don't care. I learned this real quick like. Plus, if it's only costing 160usd. You do get what you pay for. 72/160 is 45¢ a month so. Can't really argue with materials that self break down..

(And I'm the anti Beaumont guy, I gotta be realistic however)
 
To update...... KMG/Beaumont is sending me a replacement wheel at no charge (shipping cost only) They said they will be making inquiries with the companies that do the rubber bonding (Beaumont makes the aluminum hubs in house). I plan on sending my old wheel to Sunray for recovering to have a back-up on hand.
Saludos
J
 
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