Roller Shaft Breakage

Sounds like an overload condition.

More information is needed

1. type of material

2. Hardened or not hardened

3. shock loading?

4. vibration from other equipment running nearby?

5. type of start and stops

6. Are the shafts built to the same spec as the original shafts? If the material is a lower grade material, there will be more breakage.

7. Can you post pictures of the shaft and of the work enivornment?

The more information you can give us, the better help you will get.

When was the original equipment manufacturer contacted for advice and why has that advice been disregarded?

Most failures of this type are due to stress fatigue, if it is premature failure, then it could be many things, poor maintenance, overloading equipment, design flaw, wrong metal type or size....

http://www.tcreng.com/download/tcr-whitepaper-failure-analysis.pdf

I'm starting to see a pattern here.

the belt tensioner is probably siezed and the belt is getting too tight in cold weather. it is a large roller slung under the head stock and will have heavy weights attached to it. the tension roller must be able to move up and down in the slides to work correctly.

P.Nithin Kumar,

You seem to be having multiple failures.... Was all of this designed and commissioned from the same firm, or built buy the same crew or what???

All the well experienced posters are giving you good points, but it appears to me you need to do a root cause on the system and not just each component.

Cylinder, as easily stated is failing at its weak link.

Roller shaft obviously same,

STOP have a coffee, smoke or what ever, look at the system, not just individual failures.

While we are at it, I need a job.... Need someone to straighten this out, contact me

Oh and I left out your coupling failure, come on man, put em all together. Look at the SYSTEM, its parameters, limits, and its actual operating conditions.

You will find your answer

If not you may be sitting on the 8th wonder of the world, with so many associated failures but none in common.

Spooky failures at a distance?

More simple/stupid than spooky once they are all put together and analysed.

I bet there are three or four people scratching there heads over this with degree numbers longer than my last name, making them the "hot sh*t" in there field....

I see more and more of this BS each day, its disgusting. Sometimes very dangerous, in the oil and gas sector the one with the fancy degree gets the job while the one with true experience is left with his thumb up his ars,,,,

when you say you have checked the alignment and it was OK. Breakages of this type commonly are due to a stress concentration at the neck. This shaft rotates and even a very small off angle means you are bending the shaft back and forth every time it turns, and in time this causes the failure. What is the angle of the broken shaft at the failure point? Straight across, or at an angle?

One was to test this is to free wheel it and see if it has a recurring bind point.

Quite often the bearing pads for rollers like this are allowed a little 'wiggle' room to avoid this problem. Has someone tightened things down so the wiggle is prevented?

Photos or drawings please...

Many questions and no answers.

Is this a head end. tail end, drive pulley, return roller, load roller, bend pulley or take up pulley?

Is there an incline and if so, is there a backstop attached and where?

Are you using a soft start or PLC or is it controlled by a magnetic starter?

Are all other pulleys or rollers turning freely?

Is there a delay upon starting and stopping or does this possibly get hammered from constant on off conditions?

In other words the problem may not be with the shaft, but other conditions may be causing this weak point to take all the stress.

Need a lot more input!

Three separate failures posted by this person the same day, presumably all the same system, different components... 99,5% sure the RCA will all point to the same problem.

the other possibility is that the OP discovered this place & thought we may be able to solve all of his facilities nagging problems

for this to happen we would need much more complete descriptions of the equipment & the operating conditions, chances are there would be a member with some knowledge of the foibles.

for a thread to get the maximum exposure, there needs to be sufficient info to catch the interest the local experts in the title & 1st couple of lines. in most cases 90% + of the audience subscribes in the 1st 24 hours, due to the layout of the homepage & daily digest

the path to solutions is further compounded by multiple problems being posted, which puts a certain spin on the wild speculation part of our program

Does the neck reduction have radius, or does it have a abrupt angle? I have seen shafts break at the reduction point when the reduction has a abrupt angle or has not been stress relieved at the reduction point.