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  1. sokenyou

    Shaft failed due to reversed torsional fatigue?

    Thanks everyone for your input The shaft was in a pulley/sprocket No record of replacement of this shaft since the machine was commissioned but our work order system is only good from year 2010. Thanks!
  2. sokenyou

    Shaft failed due to reversed torsional fatigue?

    Hi Everyone, I got this failed shaft from work (please see the attached). It's the main drive shaft for our Bath Tissue Converting machine - we called it the knock off paddle. Based on what I saw and what I read from the book "How Components Fail", it looks like a Reversed torsional fatigue...
  3. sokenyou

    Helical gear failure, is it misaligment or overload?

    Thanks everyone for the great feedback. The Conveyor system should be running continuously non-stop except every Monday on shutdown PM days BUT due to the deficiencies in our sortation systems, the conveyor starts and stops upteem number of times in a day. The guys here including the...
  4. sokenyou

    Helical gear failure, is it misaligment or overload?

    Thanks everyone for your input. We are now investigating if someone had jammed something in the conveyor that caused this overload (if it is true), but also the last time this gearbox was replaced remains a big question mark. The Maintenance Mgr claimed that the gearbox was in there for over 15...
  5. sokenyou

    Helical gear failure, is it misaligment or overload?

    Hi Desertfox, Thanks. Have you checked the 2nd attachment? Please also see the attached. It's taken after it's cleaned out of grease. Thanks! Khttp://files.engineering.com/getfile.aspx?folder=8d131f57-59b5-43d5-8aa9-c362b67280f0&file=099.jpg
  6. sokenyou

    Helical gear failure, is it misaligment or overload?

    Sorry, attached is a better picture of the failed helical gear. Thankshttp://files.engineering.com/getfile.aspx?folder=a51e22dd-a4c3-4d60-8471-7a57776aab3c&file=102.jpg
  7. sokenyou

    Helical gear failure, is it misaligment or overload?

    Hi Everyone, I have this failed gearbox, which is pretty small, driven by a 1.5 HP motor at 1760 rpm. It drives a what is called Zero pressure conveyor. It failed and caused some downtime. My Manager said it's not just an age thing, it's an overload but only a section of the gearteeth wore out...
  8. sokenyou

    Roller shaft failed

    Thanks mfgenggear for all the useful links....greatly appreciate it. After reading all your comments, especially vpl and cockroach's, I feel bad.... I agree I should've done the engineering analysis properly and get to the bottom of it to provide good recommendations. Thank you very much.
  9. sokenyou

    Roller shaft failed

    Thanks mfgenggear, I want to do a full analysis but budget is an issue here. I can't just do a vibration analysis and it turns out it's a waste of money. You said I am not giving out enough information, but what information you think it's missing that I haven't provided?. Please kindly advise...
  10. sokenyou

    Roller shaft failed

    Another shaft went this morning! Same failure - rotation bending. I am out of idea except spending $30,000 for a brand new roller from the vendor This is a bitch! I have gone through a few directions 1. Alignment - we used self-aligned bearings 2. Heat Treatment - hot rolled steel and don't...
  11. sokenyou

    Roller shaft failed

    The shaft broke within two weeks last time and the shortest time it lived there was 5 days. The one we have in now has been there for 10 days and we are praying hard that it will run for a long time. Is there a possibility that the root cause of the problem is heat treatment of the steel or the...
  12. sokenyou

    Roller shaft failed

    Hello All, We found some cracks on the shaft very close to the bearing sleeve. We are now leaning towards fretting corrosion, BUT here is the thing, we are pointing our fingers at everything that could possibly leading to microscopic motions of tightly fitting parts, however, why didn't it...
  13. sokenyou

    Roller shaft failed

    Hello Dan T, Please see attached - dimensions of the shaft and the roller. Thanks. Regards, Kenneth http://files.engineering.com/getfile.aspx?folder=5e4dcc5f-b935-4978-bac7-426139c8214d&file=Failed_shaft_dimensions.doc
  14. sokenyou

    Roller shaft failed

    Hi Terry, Yes, the bearing used is a ball bearing unit with a self-aligning flange mount and a set screw on the inner race. The fit between the bearing zone and the shaft is a couple of thou according to what the Mechanic was saying. However, I don't understand why this (clearance and...
  15. sokenyou

    Roller shaft failed

    Thanks asimpson....speed was up 30% but not loading. Just a note too although speed was up 30%, it's still way below the designed speed, so it's just mind boggling and I don't see where the fretting corrosion came from? Between the shaft and the bushing???? Thanks.
  16. sokenyou

    Roller shaft failed

    Thanks Scott, yes I have picture for you to look at. In fact, I was told that it was fretting corrosion that caused it but we are iffy about this because it's not subject to high loads with other parts and it was in the mill for two weeks.... again, I still haven't figured out what to do next to...
  17. sokenyou

    Roller shaft failed

    In a paper converting mill, one of our draw roller shaft failed at the weakest point (near the bearing and chamfer with the radius of 0.5). Rachet marks (but shiny) indicates that fatigue cracks were initated at a few locations along the groove. The eccentric pattern tells me that the load on...

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