Standard torque values for threaded fasteners

[davidmxli]

Hi!
I work at a company where part of our products are cable & harnesses assemblies, as well as some eletrical racks.
My question is (and sorry if I didn't place it in the correct forum):
We have a requirement from one of our customers, that states: "If not specified by the customer, standard torque values must be used."

What are "standard torque values"? Is there any standard document where I can find some sort of table or further information on standard torque values?

Thanks in advance for any help provided.

Have a great day!

 

[Jim Wynne]

Re: Standard torque values for threaded fasteners?

If that vague statement is a customer requirement, I strongly advise you to consult with the customer. They might have a different idea about what "standard" means.

 

[davidmxli]

Re: Standard torque values for threaded fasteners?

Yes, I understand, that was kind of my thought, but I was wondering if by any chance there is a SAE, ASTM or another recognized standard with values for torquing

 

[Jim Wynne]

Re: Standard torque values for threaded fasteners?

Torque values are controlled by a lot of variables, such as fastener material composition, the material composition of the thing(s) being fastened, safety considerations exclusive to a given assembly, clamp load requirements which might include washers, etc. etc.

There is no one-size-fits-all standard.

 

[normzone]

Re: Standard torque values for threaded fasteners?

Yes. If left to your own devices, you could develop a set of requirements based on researching and sorting out all the variables listed above, which is probably what your customer hopes you will do so they don't have to do it.

The good news is that in your industry/product line(s) the variables are limited and once you've done the homework, you should come away with some values you can consistently apply for given fasteners in given situations. The bad news is that this is a homework project for somebody.

 

[davidmxli]

Re: Standard torque values for threaded fasteners?

Ok, I get it
Any clues or suggestions where can I search to begin with this homework?

 

[dgriffith]

There was a thread just recently about whether to torque the head or nut on a nut/bolt assy. Search the forum. It's not too old.

During that thread, I searched the ENTIRE INTERNET, it seemed like... try 'fasteners'.
As stated, many variables. The material you are clamping together, the use of washer of not, fastener materials, etc.

Very little of the torque applied goes to actual clamping force. Most is eaten up in frictional forces-- the bolt head rotating against the material (hence, use a washer or no washer?), threads against mating threads ("lock-tite", lubricants, etc.) and so on.

 

[PaulJSmith]

Re: Standard torque values for threaded fasteners?

As Jim stated above, I would suggest you begin your search with a phone call to your customer's Supplier Quality Engineer.

If they are unable or unwilling to offer their advice (which is unlikely), then your fastener supplier(s) should be able to provide you with the ratings for their fasteners.

If you are using them on softer materials such as composites, well, that's a whole different ballgame requiring the input of the engineers who designed that material.

 

[Vthouta]

http://www.boltscience.com/pages/nutorbolttightening.htm

http://elsmar.com/Forums/showthread.php?t=67269&highlight=torque