All Member Open Forum

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[Segun]
[B.tech, MEM]
[QA/QC & Parts Person]
[British Columbia]
[adedejiaderibigbe@yahoo.co.uk]
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I'm not familiar with crusher designs but a few general thoughts on failure.

If I understand your failure mode correctly, it is shaft fracture from fatigue?

1) Equipment should be designed for infinite fatigue life.  Components fail from fatigue from usually two main sources - material defect or a high cyclic stress.  There are many branches under those two, but dial in on those on your design and operation and somewhere below that you will find your answers.

2) If you can access the shaft fracture area easily there are several methods that can work - dye penetrant, magnetic particle, ultrasound might could be used from end of shaft to find larger cracks.  Fatigue cracking will typically start at the surface.

3) If the shaft is fractured, I don't know any way to repair the shaft.  You need a new shaft.

4) If you have the shaft design or an old shaft, any good machine shop can make you one.  Be sure to make sure you have as much of specifications as you can around material and detail designs.  Likely there may be areas that need a design improvement if you are having failures.  Don't just fix it, improve it and solve it.

Good luck.

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Randy Riddell, CMRP, PSAP, CLS
Reliability Manager
Essity
Cherokee AL
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Hi Charles,
I can only respond to your question about NDT on the shaft. Back in the 80s and 90s we had a team of NDT techs that developed a series of procedures to conduct Ultrasonic crack detection on a number of large shafts that we had on our 100 cu.yd. earthmoving draglines. Some of the shafts were 24" in diameter and 12' long. We would preserve old shafts where these techs would qualify a procedure that would be used proactively to find cracks in the various shafts that were installed on machines. The only requirement was that the end(s) of the shafts were accessible. The number of finds was amazing and to break a shaft that we didn't know was in a state of potential failure was almost zero.

My recommendation would be that you find someone that is well versed in utilizing UT for crack detection, let them qualify a procedure for the particular shaft you want to monitor and then set up a schedule to proactively UT that shaft or shafts.

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Terry Taylor
Taylor Reliability Consulting
St. Johns, Florida
ttaylor@taylorreliability.org
919-537-2812
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Yes. Ultrasonic crack detection is pretty common and can be a great tool for this, however you need someone that is experienced in the tools they are using.  Using U/S in this manner there is "beam spread" and if the shaft has several step downs, or diameter size changes, which they typically do, the technician should be able to tell them apart from cracks, and even then this testing may not be definitive. Dye penetrate testing will find smaller cracks that are not visible otherwise, but you would need to pull the shaft out of service.  One option would be to use U/S testing prior to pulling the shaft and then if cracks are probable you could pull the shaft and do a dye penetrate. 

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Gentry Fugate
Reliability Program Manager
Rockwell Automation
Milwaukee WI
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Original Message:
Sent: 01-30-2024 06:43 AM
From: Terry Taylor PE CMRP
Subject: Primary Crusher - Main Shaft Failure - Kawasaki KG 15522

Hi Charles,
I can only respond to your question about NDT on the shaft. Back in the 80s and 90s we had a team of NDT techs that developed a series of procedures to conduct Ultrasonic crack detection on a number of large shafts that we had on our 100 cu.yd. earthmoving draglines. Some of the shafts were 24" in diameter and 12' long. We would preserve old shafts where these techs would qualify a procedure that would be used proactively to find cracks in the various shafts that were installed on machines. The only requirement was that the end(s) of the shafts were accessible. The number of finds was amazing and to break a shaft that we didn't know was in a state of potential failure was almost zero.

My recommendation would be that you find someone that is well versed in utilizing UT for crack detection, let them qualify a procedure for the particular shaft you want to monitor and then set up a schedule to proactively UT that shaft or shafts.

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Terry Taylor
Taylor Reliability Consulting
St. Johns, Florida
ttaylor@taylorreliability.org
919-537-2812
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Hi Charles,

I am not familiar with Kawasaki crushers, but they seem very similar to the FL Smidth ones I am used to working with. I can't speak on the NDT side of things, but we replace our crusher mantle liner internally and have 3 main shafts that we rotate in and out of service. Replacing the mantle allows our technicians to do a thorough inspection of the shaft before installing a new mantle liner. We do 80,000 to 100,000 tons a day here and we have never broken a main shaft. 

For parts, I would suggest reaching out to Optimum Crush in Wisconsin or FLS directly in Salt Lake City. 

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Tyler Hamilton CMRP, CRL
Maintenance Specialist
Agnico Eagle Mines
Paradise
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I do not have experience with Kawasaki crushers, but have seen UT inspections completed on the vertical shafts of coal mills in power generation.  This was awhile back but I had worked with both Team Industrial and Acuren.  

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Luke Soltis
Manager
Bearingpoint
Chicago IL
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Good afternoon ,

I am not familiar with the kawazaki Crusher but Do yo mind sharing some more details or picture of it .

Here is my 2 cents:

1) The expected useful life is determined by material, design specs, and application. The cusher seemed to be subjected to some impact forces.Therefore , cycle fatigue could be the reason of failure. I would recommend you to look for any damping mecanism( Nylon bushing, rubber,ect...)  to dissipate energy at impacts.

is the shaft material corrosive( Carbon-steel etc..)?

is it a full shaft with the same diameter all along  or it has been narrowed down on the end to fit the gear etc... ( machine work weakens shaft)?

is it an hollow shaft ( the welding point are the weakest point) 

 Sometine you can use the S-N curve to see where you are in terms of fatigue failure or to determine if the shaft can reach infinite life ( 25 years or plus)

2) Ultrasound is definately the right tool as suggested by the peers.

3) It really depends on the shaft design , is it a full solid shaft or it is a varying geometry to fit the application?

4) if we have some details I would imagine any local machine shop can help fabricate.

Thanks 

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Cheick Rouamba
BSME-MS-CMRP
Maintenance Manager
Richmond, Tx
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