BROKEN BOLTS 2

[Prime9.9]

Hi,

Im facing this problem frequently now,my bolts are always breaking at a regular interval . The bolts are unit of torque hub speed reducer. How to identify the reason for this issue and rectify it. Please provide your kind feedback on this issue.

Thanks

 

[MacGyverS2000]

Fatique, overstress, undervalued design... the list goes on. Without some concept of WHAT is breaking, we can only hope to guess at the root cause.

Perhaps if you gave us useful data we could provide a useful answer...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[dik]

size, thread type, material, installed torque, preload, etc.?

Dik

 

[Screwman1]

Time, Environment, finish, assembly strategy, etc. We would need a lot more detail to even guess at a root cause.

 

[drawoh]

Prime9.9,

My guess is that you are putting too much force on the bolts.

--
JHG

 

[dik]

Drawoh:

Good guess... the old adage, "Tighten 'er until she cracks, then, back off half a turn", comes to mind.

Dik

 

[Tmoose]

" Please provide your kind feedback on this issue. "

My feedback is similar to that of other posters, and that is MUCH more information is required to understand the problem, and understanding is required to solve any problem efficiently.

Be sure to identify which torque hub product you are referring to .

https://www.oerlikon.com/ecomaXL/fi...Torque_Hub_Selection_Guide_1210_PDF_Order.pdf

 

[Prime9.9]

I'll provide more details soon gents.

Thanks for your understanding.

 

[Prime9.9]

The bolt is broken at the thread side,

11HBX02F80GZ036 The model of torque hub unit.

 

[LittleInch]

That does not classify as "more information "

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Prime9.9]

Hi,

Below is the attached picture of the torque hub along with the bolts that break.

Bolts is M24x300mm.

Also,is it advisable to lubricate the bolts before fastening it.

Thanks&Regards

 

[Metalfixer]

Are those the original bolts that are breaking? Looks like they should be wheel studs, a type of ribbed shank bolt,
in a reamed hole on the torque hub. Just my guess.
Larry

 

[Prime9.9]

No these are not geniune fasteners for the torque hub,still awaiting original bolts from OEM.

 

[Prime9.9]

And it's a normal threaded bolt.

 

[racookpe1978]

You don't seem to understand a few fundamental things.

You have NOT defined the specification, material, nor torque being used to install these bolts.
"Ordinary bolts" is NOT describing ANY design feature of the bolts!
Go measure them again: They do not scale at M24 based on the size of the text and embedded/stamped label information for the manufacturer in Indiana. Yes, they may be metric - even though made in the USA. But these bolts do not appear to be big enough to be M24.

Your bolts are breaking because the initial torque applied during assembly, and the added load imposed on them during operation - increased by unknowns you refuse to tell us about such temperature, environment, chemistry, start-stop cycles or sudden dynamic loads! - are greater than the ability of the installed bolts to withstand. It is as simple as that.

To continue a "lessons learned" criticism: Yes, lubrication during assembly is ESSENTIAL. However, the wrong lubrication in the wrong environment applied to the wrong alloy bolt-nut-base metal combination with the system fluid or chemistry "MAY" caused further harm. Or it may not. We do not know enough to judge at this point. Your photo shows no sign of lubrication, of torque applied, of turn-of-nut-records, or of ANY indication that a sequential torque is being applied around the joint.

At that size of the claimed large M24 bolt and nut, the METHOD of torquing is critical: You should be applying the torque (which is needed to get the pre-load required for successful operation) in 3 or four stages towards maximum torque (of 25%, 50% 75% 90% and final torque) by a qualified operator using a calibrated torque wrench in a star or hex pattern around the entire joint. Is this being done properly? Have you inspected the operators ACTUALLY DOING the installation? If they are using an air impact wrench to "just drive them down dry" - then, YES. THE BOLTS WILL FAIL.

 

[Prime9.9]

Thanks a lot for your feedback gents!!

 

[LittleInch]

They do look too small for me.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Strong]

OP Stated:
"How to identify the reason for this issue and rectify it. Please provide your kind feedback on this issue."

The first failure of the OEM product was from torque overload, assuming product was manufactured and installed properly. If replacement bolts were not OEM, then material strength, shoulder diameter, and fastening torque were probably less than OEM. Failure to reduce operating static and dynamic torque combined with lower strength fasteners would lead to repeated frequent failures.

What to do? Torque can be measured at input shaft with strain gage telemetry system (I use Binsfeld) or other methods. Dynamic torque and torsional vibrations can be reduced with appropriate input shaft coupling. The overall drive system would have to be evaluated to see if operating torque can be reduced or justify need for larger torque hub rating.

Walt

 

[racookpe1978]

Appear to be CAD-plated hardware store bolts. Certainly no Grade 8 markings on the visible nuts.

 

[Strong]

Perhaps surgery is needed when a Band-Aid is ineffective!

Walt