Re: Shrink Disc Bolts Tightening Pattern
Only the manufacturer knows why and it is always best to follow their recommendation. It would all have to do with their particular design.
The big key is to continuously follow the required pattern until the full torque is reach on every bolt. Failure to do so could be a disaster waiting to happen. ■
Gary Blenkhorn
President - Bulk Handlng Technology Inc.
Email: garyblenkhorn@gmail.com
Linkedin Profile: http://www.linkedin.com/in/gary-blenkhorn-6286954b
Offering Conveyor Design Services, Conveyor Transfer Design Services and SolidWorks Design Services for equipment layouts.
Who Is Who
Dear Mr. Ganesh,
shrink discs: device that by tightening compresses a hub onto a shaft in order to enable transmission of torque from hub to shaft
location: does not lie in direct power train
tightening: CIRCULAR pattern, usually several rounds of tightening required
remark: starshaped tightening is MALPRACTICE.
locking bushes, clamping elements etc.: device that by tightening expands thus fixing its position and related parts
location: in between hub and shaft, takes part in transmission of torque from hub to shaft
tightening: PREtightening in crosswise or starshaped pattern, usually two+ rounds of tightening --> as per specific OEM, FINAL tightening in CIRCULAR pattern might be required, usually several rounds
Could you pls. check, whether you encountered these different devices under a common name?
Regards
R. ■
Re: Shrink Disc Bolts Tightening Pattern
Thank you Mr.Gary & Mr.Ronald.
Here I was referring Shrink Discs only ( not locking bushes or clamping elements used in conveyor pulleys ).
The shrink disk concept suggests that the removal of drive part from the driven part is very simple and fast.
But twice, I found very difficult in removal of driven part, since the tighening sleeve & tightened shaft were in together operation for many years.
Is there any remedy for this ? Can we use any chemical coating in between them ?
The chemical should not hinder the gripping of sleeve on the shaft, but it should help for easy dismantling.
Thank you once again & best regards, ■
Who's It?
Dear Mr. Ganesh,
then i'd very much like to learn more about those few other suppliers you mentioned in your original post.
I think that any application of an additional chemical during assembly of a shrink disc would inflict badly on safe functionality. Best you talk to some OEM on this. However there's chemicals to be applied when dismantling poses a problem, then again pacience and your skilled maintenance craftsmen will know another trick or two i think.
Regards
R. ■
Re: Shrink Disc Bolts Tightening Pattern
Having worked in the salt mining for many years that problem was there many times. Even though manufacturers say to install with a dry fit - our millwrights would use a product called "Never Seez" and it did the trick. http://www.bostik-us.com/our-brands/never-seez Without it they would never be able to remove them. ■
Gary Blenkhorn
President - Bulk Handlng Technology Inc.
Email: garyblenkhorn@gmail.com
Linkedin Profile: http://www.linkedin.com/in/gary-blenkhorn-6286954b
Offering Conveyor Design Services, Conveyor Transfer Design Services and SolidWorks Design Services for equipment layouts.
Re: Shrink Disc Bolts Tightening Pattern
Thanks a lot Mr.Gary. I will check.
Regards, ■
Re: Shrink Disc Bolts Tightening Pattern
Originally Posted by Gary Blenkhorn
Dear Mr.Gary,
The shrink disc concept is similar to tightening of taper bore bearing on the adapter sleeve by the lock nut.
Were these coumpounds / sprays used only for shrink disc applications ? Or also between the shaft and adapter sleeves ?
Thanks a lot for sharing the finest informations.
Lots of regards, ■
Somewhere In The Dark
You may call me Mr. Suspicious & and with all due respect, however, i think there should be some professional inspection on site on item in question & a decision be made due all required diligence before jumping the fence of OEM prescriptions.
Then +: One good solution in one field of application could be, but must not necessarily be, the good & generalizable one for everything (seemingly) similar.
Then ++: There's two worlds as there's new installations vs. a retrofit / refurbishment / re-assembly after suffering the pockmarks of fretting etc.
Regards
R. ■
Tightening Method For Shrink Discs
Dear Mr. Ganesh,
different suppliers may have different methods in their manual how to tighten the screws of a shrink disc, at the end the aim should be the same: to assemble 3-part shrink discs in that way that the two flanges are in a parallel position over the full tightening process and for 2-part shrink discs that the faces of inner- and outer ring are parallel over the full tightening process.
Regards,
Ernst Fritzemeier
■
Re: Shrink Disc Bolts Tightening Pattern
Thank you Mr.Ernst Fritzemeier, Mr.Gary & Mr.Ronald.
Here in the discussion, I am referring the 3 part shrink disc ( Parts : Two flanges, the center tapered ring, O ring between flanges , High tensile bolts ).
If these parts of same shape & concept is same for many manufacturers, how could the tightening procedure ( continuous or star pattern ) can be
1) different between manufacturers
or
2) between manufacturer and end user
or
3) between the first time assembly and in subsequent assembly.
If "anti-seize" compounds can do wonder for end user, why are they denied by shrink disc manufacturers ?
Thanks a lot for all who make me learning.
Regards, ■
Detail Clarification
Whoever may be concerned...
Imo as a point to be made: When it comes to the assembly of a shrink disc, there's a difference to be made between primary positioning, and the (final) tightening.
So, the principles as presented by Mr. Fritzemeier are to be followed as a general rule, and Mr. Mulanis hints are the guideline to how it is to be done in the workshop, with the last = deciding word to come from the supplier of the shrink disc.
I think now, a generalization concerning assembly and tightening of shrink discs is not appropriate for such mechanical appliance. I feel as the mechanical engineer mentioned by John: To keep an eye on things (is the good practice).
A good day to all!
Regards
R. ■
Re: Shrink Disc Bolts Tightening Pattern
Hello,
Referring to my earlier information, I add one more sentence into the same.
After completion of tightening the diametrically opposite screws; a final safety check tightening can be done for screws in straight sequence, 1, 2, 3, 4, etc. (circular sequence), to ensure that none of the screw has been missed for tightening. Screw tightening by any style should always be in few rounds to reach the final tightening.
The information by me is on the basis of general analysis.
As stated before, the manufacturer's recommendation prevails.
Regards,
Ishwar G. Mulani
Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)
Author of Book : Belt Feeder Design And Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
Re: Shrink Disc Bolts Tightening Pattern
Hello,
Follow the installation instructions as informed by manufacturer / supplier of shrink disc to uphold the performance warranty. However, following general information could be of interest.
The purpose is to create radial compressive pressure uniformly along entire periphery, while maintaining concentricity. It seems, this can better be achieved by tightening of screws diametrically opposite, like fixing of car wheel.
Also tightening of screws in three-four steps (rounds) will avoid harmful temporary strain in shrink disc components. First round of tightening could be by say 30% torque, second round by say 60% torque, third round by say 90% torque and last round by 100% torque, etc.
The manufacturer of shrink disc will be the right source to get the factual information.
Ishwar G. Mulani
Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)
Author of Book : Belt Feeder Design And Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
Re: Shrink Disc Bolts Tightening Pattern
Originally Posted by I G Mulani.....Star Pattern : The purpose is to create radial compressive pressure uniformly along entire periphery, while maintaining concentricity. It seems, this can better be achieved by tightening of screws diametrically opposite, like fixing of car wheel.
Continuous Pattern : Also tightening of screws in three-four steps (rounds) will avoid harmful temporary strain in shrink disc components. First round of tightening could be by say 30% torque, second round by say 60% torque, third round by say 90% torque and last round by 100% torque, etc.
The manufacturer of shrink disc will be the right source to get the factual information.
Dear Sir,
As I understood from shrink-disc manufacturers, "Star Pattern " is refused. Continous pattern is preferred. It can be clockwise or anti-clockwise. Even after the last round of 100%, need to tighten the bolts with few more rounds, till to ensure 100% torque value is achieved.
Thanks a lot & Best Regards,
S.Ganesh ■
Clever Bolting Techniques.
Once upon a time I took a 3 axle truck into the benchmark tyre workshop for new front tyre fitting. After the job was correctly completed I signed the papers which advised me, strongly advised me, to take the vehicle in for inspection at any depot within the week. I duly did this after some days of mixed driving around rural Wales and on UK motorways. It was quite alarming for me to learn that 2 nuts had loosened more than half a turn. Previously I had considered the plastic indicators on European trucks to be a waste of time. I used the argument that if the nut made a complete revolution no one would know that the nut had loosened. By law, European drivers are required to check wheel nut tightness, and tyre pressure, before accepting the vehicle as roadworthy, daily. Of course it's a crazy notion and only gets superficial attention. That doesn't lessen the risk.
Point is, bolted connections are pretty reliable structurally and statically but when it comes to dynamics they need a lot of help. It doesn't matter how they are tightened: they'll still loosen given half a chance. When I was an aeronautical engineer the joints always incorporated lock washers or locking wire. (Aeronautical engineer will select the correct grade, tighten to specification, secure and pray. Mechanical engineer will select the correct grade, tighten with a ring spanner, slip an extension bar on for final tightening and keep an eye things. Civil engineer will select the nut the next size up, finger tighten it and go down to the pub until the job rusts up solid.) They all work in their way and it becomes a matter of choice and pure science is, after all, pure science. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Shrink Disc Bolts Tightening Pattern
Dear Experts,
Today I was browsing internet on above subject, shrink disc ( keyless power transmission ) . Few suppliers are mentioning the bolts should be gradually tightened ( in steps to attain the full torque value ) all the bolts successively either in clock-wise or counter clockwise direction. But few others suppliers are recommonding to tighten the bolts in star ( opposite to opposite ) formation.
Though the principle is same for all the shrink-discs, how the tightening methods could be different ?
Requesting your valuable opinions please.
Thanks & regards, ■