Ball Bearing Age vs. Wear

[wings&wheels]

Does age or time spent in only static load significantly 'wear' a ball bearing? Looking to the mechanical engineers, tribologists or anyone else qualified (or not) here for thoughts. I'm a glorified accountant/bored exec and know my limits

This is in relation to a Porsche IMS bearing, but not looking to discuss the IMS issue.

The replacement, upgrade, that we chose is a hybrid ceramic ball bearing with a service life stated in miles and years. While I understand the mile limit I question the calendar limit. That said, I understand why a manufacturer would put service limits, and its not all greed. However, my cars generally see 1-2k/yr and I can't see replacing a serviceable bearing unnecessarily (it is invasive surgery); both cars are at the time limit with maybe 1/5th of the allowed miles.

My question is how much of an effect does time, just sitting with a static load from the chains & tensioner, have on a quality ball bearing? We will assume fresh, quality oil, etc.

 

[billt460]

My question is how much of an effect does time, just sitting with a static load from the chains & tensioner, have on a quality ball bearing? We will assume fresh, quality oil, etc.

I'm not an engineer, but just applying common sense would tell me a rotating bearing, that is instead sitting motionless, would have zero effect on actual wear, simply because nothing is moving.

With springs, (from everything I've read), it is much the same. Cycling, (movement) is what wears them out. Not sitting stationary under pressure. The springs on your car are a good example. As are springs in firearm magazines and recoil springs in semi autos.

The more the car is driven, and the more the firearm is shot, the faster the springs will reach the end of their service life.

Cycling causes wear, not holding a load stationary. As far as the bearing sitting static, I would be more concerned about corrosion in a wet climate, than I would about wear. And even that is not a concern if the bearing is properly lubricated. As always YMMV.

 

[fantastic]

I would assume a very long time. I suppose the major wear would be corrosion of the bearings that could effect their lifespan in TIME. However, That could be addressed by starting up the engine at least once a year or so to re-coat the bearings with oil. Unless these are not coated by oil. In that case I've used grease to pack them & even that can last a long time.

 

[Jetronic]

I'm not an engineer, but just applying common sense would tell me a rotating bearing, that is instead sitting motionless, would have zero effect on actual wear, simply because nothing is moving.

With springs, (from everything I've read), it is much the same. Cycling, (movement) is what wears them out. Not sitting stationary under pressure. The springs on your car are a good example. As are springs in firearm magazines and recoil springs in semi autos.

The more the car is driven, and the more the firearm is shot, the faster the springs will reach the end of their service life.

Cycling causes wear, not holding a load stationary. As far as the bearing sitting static, I would be more concerned about corrosion in a wet climate, than I would about wear. And even that is not a concern if the bearing is properly lubricated. As always YMMV.

Think of a bearing that doesn't make full rotations, but rocks left/right. There's no mileson that but the load is taken by the same few balls all the time.

 

[billt460]

Think of a bearing that doesn't make full rotations, but rocks left/right. There's no mileson that but the load is taken by the same few balls all the time.

Possible. But look at roller rocker arm bearings on overhead valve engines. I've never seen or heard of them wearing out. The same with valve springs.

They cycle tens of thousands of times per hour. (Half the RPM of the engine). And they do this for hundreds of thousands of miles. And the valve train on any engine is the last set of parts to receive oil when first started, just based on the fact it's furthest from the oil pump. They rarely fail or wear out.

It's almost funny when you think about how much ammunition it would take to actually wear out a firearm magazine spring, when compared to an automotive valve spring, based solely on the amount of cycles each undergo in their lifetime.

 

[Jetronic]

I've seen great wear in roller bearings used in wishbones (evobus citaro). The bottom roller was always damaged. Use the wrong grease and this happened fast.

The rocker arm bearings are loaded hevily when pushing down the valve, but not when the valve comes up, it could be they actually rotate because of this.

 

[RooflessVW]

LN is concerned about corrosion.

If you keep fresh oil in your car, I wouldn't worry about time.

 

[willbur]

Does age or time spent in only static load significantly 'wear' a ball bearing? Looking to the mechanical engineers, tribologists or anyone else qualified (or not) here for thoughts. I'm a glorified accountant/bored exec and know my limits

This is in relation to a Porsche IMS bearing, but not looking to discuss the IMS issue.

The replacement, upgrade, that we chose is a hybrid ceramic ball bearing with a service life stated in miles and years. While I understand the mile limit I question the calendar limit. That said, I understand why a manufacturer would put service limits, and its not all greed. However, my cars generally see 1-2k/yr and I can't see replacing a serviceable bearing unnecessarily (it is invasive surgery); both cars are at the time limit with maybe 1/5th of the allowed miles.

My question is how much of an effect does time, just sitting with a static load from the chains & tensioner, have on a quality ball bearing? We will assume fresh, quality oil, etc.

IMO, its a simple money grab to replace based on age. I got the IMS replaced with the hybrid and this issue crossed my mind. The bearing itself and replacement cost are crazy expensive. The OE bearing is a very cheap bearing commonly used in water pumps, alternators, etc. Probably explains the very infrequent IMS bearing failure, IMO.

 

[willbur]

LN is concerned about corrosion.

If you keep fresh oil in your car, I wouldn't worry about time.

That bearing sits half (or more) submerged in the sump. The balls are ceramic and the cages steel. If corrosion was a concern, it should also apply to all steel ball bearings.

 

[RooflessVW]

That bearing sits half (or more) submerged in the sump. The balls are ceramic and the cages steel. If corrosion was a concern, it should also apply to all steel ball bearings.

It does. One of the biggest drivers of IMS failure was a "sealed" steel bearing sitting stanky oild "garage queen" oil.

It's a wise CYA from LN, IMO.

 

[willbur]

It does. One of the biggest drivers of IMS failure was a "sealed" steel bearing sitting stanky oild "garage queen" oil.

It's a wise CYA from LN, IMO.

Yeah- the oldest preventive remedy was to simply remove the IMS front bearing seal during a clutch replacement and let fresh oil lubricate that bearing. That stanky oil resulted from oil trapped in the hollow IMS.

 

[DriveHard]

@wings&wheels - I don't know of the particular issues of this bearing, or the system you describe. I can only make comments from a former bearing application engineer perspective.

-if the components are not moving (NOT AT ALL) than you can negate your concerns of pressure on a bearing while not in use. There are MANY cases of bearings wearing while not in use, and they are almost all attributed to relative movement (even micro movement) between the races and rollers during storage. An extreme case is wheel bearings on a car after being carried by rail. The consistent rocking and solid impacts imparted on the bearings wear microscopic divits in the rollers and raceways that will lead to later spalling. Under observation it is easy to identify this is the cause of "false brinelling"
https://en.wikipedia.org/wiki/False_brinelling

-if the components are ever loaded to the point of actually plastically deforming the balls or raceway due to exceeding the static load capability, then you get true brinelling. That is when the rollers or race (usually the inner race first) are permanently deformed due to stress.
https://en.wikipedia.org/wiki/Brinelling

-Of course you have to worry about water ingress/moisture during storage...which can lead to false brinelling when a tiny rust spot develops where the roller contacts the raceway.

-Ceramic rollers increase the likelihood of these storage damages in my experience. Because the rollers are so much stiffer than the races, they are more likely to dent or wear into the races.

If the bearing was stored in a controlled environment, well lubricated, and not moving (vibrating), I would have little concern.

Oh yeah...also can get false brinelling from welding through a bearing...if the welding current flows through one, you can bet your lunch you will get damage.

 

[zzyzzx]

For something like a wheel bearing, where the grease will dry out over time, I could see this.

 

[RooflessVW]

Yeah- the oldest preventive remedy was to simply remove the IMS front bearing seal during a clutch replacement and let fresh oil lubricate that bearing. That stanky oil resulted from oil trapped in the hollow IMS.

It's still all you can do on the M97 cars without splitting the case. Seems to work.

My plan was a new NSK bearing with no seals before I sold my 996.

 

[oil pan 4]

Does age or time spent in only static load significantly 'wear' a ball bearing? Looking to the mechanical engineers, tribologists or anyone else qualified (or not) here for thoughts. I'm a glorified accountant/bored exec and know my limits

This is in relation to a Porsche IMS bearing, but not looking to discuss the IMS issue.

The replacement, upgrade, that we chose is a hybrid ceramic ball bearing with a service life stated in miles and years. While I understand the mile limit I question the calendar limit. That said, I understand why a manufacturer would put service limits, and its not all greed. However, my cars generally see 1-2k/yr and I can't see replacing a serviceable bearing unnecessarily (it is invasive surgery); both cars are at the time limit with maybe 1/5th of the allowed miles.

My question is how much of an effect does time, just sitting with a static load from the chains & tensioner, have on a quality ball bearing? We will assume fresh, quality oil, etc.

Kind of. It's called false brinelling. It happens in bearings installed in things like larger electric motor that are in storage or are infrequently used. These bearings developed wear pits due to vibration from nearly by motors or even busy train tracks. It does not appear to happen to uninstalled bearings.
The last place I worked had someone from maintenance go out to the wearhouse and rotate any spare motor bigger than 150hp at least 90 degrees.

 

[wings&wheels]

Thanks all. My plan will be to keep driving and monitor the filters, etc. as I always do.

Despite the low usage, the cars are in dry storage, with annual changes of Redline 10w-50 and are always run up to temp when they are started.

 

[willbur]

Thanks all. My plan will be to keep driving and monitor the filters, etc. as I always do.

Despite the low usage, the cars are in dry storage, with annual changes of Redline 10w-50 and are always run up to temp when they are started.

Got my curiosity up- checking google comes up with ceramic hybrid ball bearings being 10x more resistant to corrosion than all steel

 

[wings&wheels]

Got my curiosity up- checking google comes up with ceramic hybrid ball bearings being 10x more resistant to corrosion than all steel

The balls will be, but the races are still hardened steel.

 

[willbur]

The balls will be, but the races are still hardened steel.

the bearing manufacturer stated the ball bearing- not just parts of it. <srug>

 

[DriveHard]

Kind of. It's called false brinelling. It happens in bearings installed in things like larger electric motor that are in storage or are infrequently used. These bearings developed wear pits due to vibration from nearly by motors or even busy train tracks. It does not appear to happen to uninstalled bearings.
The last place I worked had someone from maintenance go out to the wearhouse and rotate any spare motor bigger than 150hp at least 90 degrees.

I would have suggested 360+15 degrees to get all rollers through the load zone, and hopefully in contact with lubrication.