Can a ball bearing destroy a refiner plate?

[jasonf987]

Afternoon Gents,

We had a recent failure of one of our refiners, which literally destroyed the refiner plates. upon closer inspection we found a tiny ball bearing lodged in the pieces of the plate. our supplier is adament it caused the failure, i however doubt it. there are no signs of rubbing or other damage anywhere else on the plate. there are not even signs of rubbing or any damage on the ball bearing itself.

Is a ball bearing hard/strong enough to be able to destroy a refiner plate?

 

[SincoTC]

Pictures of the damaged parts would help, also of the lodged ball bearing itself and the surrounding fractured faces.

Is the ball (which would typically be pretty hard) come from one of the refiner's bearings or is it a foreign body?

I don't know much about refiners, other than their plates are used to process paper or pulp, so possibly these plates are cast. If so, and as the ball bears no marks and was "lodged" in the one of the destroyed plates, it could be that it was accidentally "cast in" during manufacture and its presence has initaited the fracture.


Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

SW2007x64 SP3.0 Pentium P4 3.6Ghz, 4Gb Ram ATI FireGL V7100 Driver: 8.323.0.0
SW2009x32 SP1.0 Pentium P4 3.6Ghz, 2Gb Ram NVIDIA Quadro FX 500 Driver: 6.14.11.7751

 

[gerhardl]

Agree with SincoTC, and: where does this come from? Could any other parts have followed and later not be found?

 

[jasonf987]

When the plates were inspected prior to commissioning there was no ball bearing present, it seems to be a foreign body.
From the evidence found it is our opinion that the centre locking cap screw securing the drive sleeve of the rotating disc to the shaft was not tightened properly, this in-turn caused excessive stress on the locking dowel pin which eventually failed.
Once the dowel failed the complete locking device was supported by the cap screw, this allowed the complete locking device to rotate on the cap screw, until the cap screw failed, see the excessive wear on the cap screw head photo.
Once the cap screw failed the complete locking device “rattled” around the centre of the refiner discs, and also the end cover of the door, causing the end cover to fail and eventually breaking sections of the inner diameter of the refiner plates off, these pieces of refiner plate then went through the refiner disc causing the damage found. This is manifested by the wear on the cap screw head.

 

[SincoTC]

From that photo, the ball bearing doesn't look like it was an inclusion and caused the failure, which isn't as fragmented as I'd imagined. Maybe as a foreign body, introduced when loading, it may have lodged into the grooves and locked the discs, overloading the fastener and dowel you mentioned. I didn't find the screw head photo you mentioned.

As I said, I'm not familiar with the construction and use of refiners. Have you seen these people?

http://www.intota.com/experts.asp?strSearchType=all&strQuery=refiner+plate

They're probobly expensive but may be worth it if there's big bucks involved!

Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

SW2007x64 SP3.0 Pentium P4 3.6Ghz, 4Gb Ram ATI FireGL V7100 Driver: 8.323.0.0
SW2009x32 SP1.0 Pentium P4 3.6Ghz, 2Gb Ram NVIDIA Quadro FX 500 Driver: 6.14.11.7751

 

[arunmrao]

How are you sure that it was a misplaced ball from a ball bearing. It can also be a steel shot,which has got lodged in the groove. This could have then got dislodged later on.


I have always been at the firing end for cast refiner plates.What material are the refiner plates made from?Possibly one of the fins might have broken. But this is not evident from the photograph.

I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
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[tomwalz]

Sounds like the supplier is trying to blame you when it is his own fault. Your real problem is that they seem to lie better than you tell the truth. I have been through this a lot of times.

Examples: We process tungsten carbide. We have brazing conveyors and the parts drop about 14” into a catch basin. I was told that that was causing the carbide parts to chip. I bought an old .410 shotgun and fired carbide parts at a concrete block wall to show just how hard it was to chip them. I was told that I was chipping parts in a cleaning / tumbling operation. I went to the craft store and bought little blue glass beads and little ceramic flower pots. I put them into a load of parts and tumbled them. The beads and flower pots survived beautifully. All this convinced the customer and gave the carbide supplier time to fix the real problem.

You can try setting up a simple experiment to prove it one way or another but the real answer is to change suppliers.


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[arunmrao]

Though not technical or ethical,is it possible that the loose single ball was planted stealthily?



I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
_____________________________________