Gyratory Crusher Failure Modes

Hello All

Top of the mornign to all from this part of the world. This is my first post and I'm not reliability Guru, just mostly been doing CM stuff. Anyway, I was wondering if anyone can assist with failure modes of Gyratory Crushers. The model we have on site is a KB 63 - 89. We had a failure recently during commision and its difficult to say what is the root cause. What we can see physically is extensive damage on the outer bushing and minor damage on the inner bushing of the eccentric. Any idea to get me started would be very welcomed in trying to provide an overal picture to the big bosses.

Thanks in advance for all the assist.
Original Post

The manufacturer or qualified rebuilder may be able to help. Was the installation and startup verified by the manufacturer or rep.? Did they use a checklist?

A drawing and pictures of the failure may help me and others here to guide you. Any CM data, i.e. vibration or oil analysis?
For Josh and others who don't know what the crusher looks like:

Possible failure modes related to:
1) Lubrication -- gears and bearings
2) Hydraulics -- controls
3) Assembly -- tolerances, fit and tightness
4) Installation -- fastener correct strength and torque
5) Design -- structural natural frequency 5) (foundation and supports)
6) Foreign metal object entered crusher

Hi Josh, I am on the Client side of things. We do have the OEM on site and who has been involved in the commisioning, check list etc. As to the eccentric object, I am referring to the ecentric bearing assembly. We are mining ore for iron.

Hello Bill, the original OEM has been involved in the process. Vibration analysis revealed up to 3x GMF and multiple sidebanding of input shaft turning speed. I monitored this but could not pick out any additional faults and the trending of the side bands and the GFM was generally stable. Oil Samples collected initially indicated were acceptable. about 3 weekss later, another sample was collected because multiple of bronze filings were found in the return line screen of the Lube Tank. Results indicated unsuitable oil so this was changed out. Shortly after the changeout, the crusher failed. At about the same time, a large piece of metal was caught in the crusher which made it diffcult to dislodged. The endresult was the crusher came off line. Recent oil samples are satisfactory. NO indication of tmperature rise in the lube lines etc.

Thanks Walt for the failure modes. With respect to Failure modes 1&6 refer my discussion above. To the hydraulics, our oil sample is satisfactor per lab analysis. In terms of Assemnly. Install & Design, we were told they were accpetable through punch list checks. I was not involved directly so I do not Know.

I had searched on line and found the Metso documents, which alerted me to think that perhaps this failure was Burnout of Eccentric Bushing mostly based on the indicator key of Bronse Filings in the screen of the Hydraulic Unit. Having said that, I am no crusher expert, and my assumptions are based Metso's COne Crushers. My question then is, is a Gyratory crusher operate in the same manner as a Cone Crusher. Can i assume that factors that cause eccentric burn out applicable to a cone Crusher such as improper lube oil, defective lube system, incorrect rotation, excessive fines in feed material etc be aplicable to a gyratory Crusher? I am genuinely concerned that wing a few weeks, the oil had deteriorated, along wih the help of a metal getting jamed in their had a failure impact on the crusher.

I am now collecting samples, on a shorter frequency, to get a trending of the oil. Our old oil, which was a 320 had an ISO Code 18/16/14. The new baseline is cleaner with ISO code 17/15/13.

Thanks guys, i really appreciate the input. If i need to add any more details, let me know. I await further discussion


Photos (1)

It sounds like the oil analysis was reflecting the wear of the bushing? If that is true, the root cause analysis should focus on what failure modes would contribute to the failure of the bushing. A few examples:

1. correct oil properties
2. within designed temperature range
3. correct clearances
4. stable mounting

and many more, I'm sure. A wear debris analysis of particle size, shape and number along with examination of the bushing wear under magnification by a failure expert metallurgist might be of value. The dis-assembly inspection report of clearances, bolt torques etc. would be important. Shaft straightness, bushing eccentricity and fit concentricity and alignment of internal parts are more points of inspection.

how is the vibration gearmesh after rebuild? High GMF is normal in some machines, but it may also reflect excessive looseness in gear shaft bearing fits.

Hope this helps, you have a tough job trying to assemble pieces of a big puzzle after the fact. A good RCFA starts immediately upon failure and the disassembly inspection is a key step.

Often factory techs/reps are covering their butts so they dont have liability. They often hide evidence. Is that possible here?
Hi Wendy, I think Bill is correct if you can add Wear Debris Analysis to your oil testing that will allow the precursor particles to abnormal wear to be detected and once any abnormal wear particles commence to appear you should be able to identify the particles and root cause their origin and reason for the abnormal wear. The cleanness target you have set for your gear lubricant is very clean and you should not get any wear being that clean but if the particle count commences to elevate again by 1 or 2 ISO classes complete a WDA and identify what the increase in particles is due to, our website has good information on Wear Debris Analysis and please feel free to download any info that may be of use, Regards Rob S -
Hello All
i have some problem in my site
there is a lot of oil leakage from around of gyratory crusher main shaft, also after remove air blower line from crusher discharge oil from that.
what is my problem?seal ring damaged?main shaft o ring damaged?
pls help me
Hello Wendy,

Not sure if you are still working on this issue, only came across this posting today. I would agree with Bill on his posting with regards to potential failure causes. In my previous position, I was a Reliability Engineer with an Iron Ore operation and had a similar failure except our crusher was in operation for a number of years, not a new install (the mine was in operation since the late 50's, early 60's). During the investigation, it was noted that the eccentric bushing will eventually fail overtime due to fatigue and this was one of the contributors to the failure we experienced, the PM was not well defined on when to change out the bushing i.e. there was no allowable limit in regards to visible damage. An inspection had taken place shortly before the failure and it was noted that the bushing was becoming fatigued/worn, however, a decision was made to continue operation without replacing the bushing. This appears to not be the problem in your case since it is a new install.

In our dealings with Metso on the issue, they were leaning towards incorrect lubrication since we were using a lube not within OEM specification. The bushing contained damage similar to the picture posted with black/dark markings around the bushing and some marks were the full circumference of the bushing. There was an actual Metso troubleshooting guide that the representative had indicating the types of bushing damage and potential cause(s). According to that document lubrication was the issue. We also did detect faults with vibration analysis a few months prior, I cannot detail the exact faults in the spectrum but the measurements were taken on the jack shaft off the motor. We also replaced the eccentric gear since a number of teeth on the gear were severely spalled. In one of your posts, you mentioned tramp metal, we had a number of issues with tramp metal and oversize ore entering the crusher and believed this increased the wear & tear on the eccentric assembly.

The mine I worked with at the time was operated by a large mining company and I reached out to different sites for knowledge sharing. One site had recently replaced the lubrication skid and had a lot of success in increasing the life of their bushings (the skid was designed by their in-house engineering team). I do not know what lubrication skid you are using but ensure it is properly sealed, the lines are not plugged, you have correct flow, and the reservoir contains a proper breather. The lubrication skid we had was very old and obsolete, there were several potential contamination points such as the inspection hatch which no longer fit properly and the lube reservoir was open to atmosphere. As mentioned your lubrication was good cleanliness wise but I believe it could be improved. The standard with the mining company I previously worked with was ISO 16/13. Also, it was mentioned that the wrong lubrication was used and switch the correct type but the failure occurred shortly afterwards. Potentially the damage was already done and even though the issue corrected it was only a matter of time before the bushing failed. Do you know why this lubrication was selected and if the OEM had made a recommendation? We had a lubrication expert on site for approving lubrications for use in our machinery and for providing support basically for anything lubrication/fuel related. Not sure if your company has such support but would recommend involvement of a Subject Matter Expert separate from the OEM for all critical lubrication decisions.

Some additional details on the failure mode, the eccentric bushing actually seized unto the main shaft, hence, the main shaft could no longer rotate on the eccentric but increased speed equal to the eccentric gear. Operations continued to run the crusher attempting to slow it down but their efforts were in vein as the crusher became plugged and we spent a week or more trying to clear ore from the crusher.

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