Torquing chart

[purode333]

Dear sir,

Normally, we find many torque chartare available for different fasteners and from different manufacture.

Is there any standard chart available or we have to go as per manufacturer recommendation for torque application.

Regards
Prasad Rode

 

[MintJulep]

You could calculate it yourself, based on your engineering knowledge of the thing that you are designing. That is something that is lacking in any chart you will find.

See faq725-536 as a start.

Other FAQ's here point to some good references.

 

[drawoh]

purode333,

Fastener torques depend on the fastener material, the joint design, the possible presence of lubrication, your confidence in your workers and tooling, and your design requirements. I don't trust manufacturer recommended torques unless I am doing exactly what they intend that I do with their stuff. Otherwise, I want to understand their assumptions. Screw torques are fairly easy to work out once your work out all your assumptions.

--
JHG

 

[Tunalover]

There's a British company called Tork Sense that sells a great program (Torksense) for calculating installation torques for many different fastners, materials and lubricants. I think it's about $150US.

Tunalover
Electro-Mechanical Product Development
UMD 1984
UCF 1993

 

[JBreunig]

I second MintJulep about doing to calculation yourself. It's really not that hard.

The article below looks at some fundamentals of bolted joints. I wouldn't design something based on a blog article, but this one at least points out some basics, and some interesting information.

https://www.xceed-eng.com/bolted-connections/

Jim Breunig P.E.
XCEED Engineering
Mechanical Engineering
FEA Consultants

 

[Ron]

Jim....self promotion is not allowed in the forums

 

[JBreunig]

My apologies for any confusion Ron. I viewed self promotion as recommending or promoting a product or service. I'm not selling a thing. This is merely a decent article on bolted connection design I thought I'd share. I could have just as easily written it in response to the question, but I thought it would be easier to go read it.

EDIT:
Is there are particular application that you're looking to use a bolt chart? If it's a standard application, it's pretty easy to make a chart.



Jim Breunig P.E.
XCEED Engineering
Mechanical Engineering
FEA Consultants

 

[dvd]

A decent short article -

http://www.portlandbolt.com/technical/faqs/tension-vs-torque-explained-sort-of/

Torque calculation without some knowledge of the actual friction coefficient is pretty worthless, but gives a quick answer to send someone off on their merry way with assurance that they are doing something consistently. The point of torque is to achieve a tension - use a torque tension calibration of some sort. Turn of nut methods could be calibrated with an indicating torque wrench for very little money and average of a few tests.

 

[drawoh]

dvd,

That article is nice, but it is re-hack of stuff we (most of us?) were taught in Machine Design. My copy of V.M.Faires used 0.15 and 0.2 as the friction factors for lubricated and un-lubricated screws, respectively. I like how the author refuses to answer questions about any materials other than the bolts he is selling.

--
JHG

 

[Tmoose]

It sounds to me like you may be approaching this from the opposite end, ie, what can the fastener take.

If I thought I knew the precise loads that would applied to a bolted joint in service, I'd add a little something for overspeed, some more for operator abuse, and double that for fight-through capability. Then, to permit the equipment to be field stripped or repaired in the woods, I'd pick fasteners that would exert that full clamping force if (under) tightened to a nominal table value using a torque wrench under high friction conditions. The assembly might end up slightly heavier, but I'd save some weight by throwing away the lock washers, and elsewhere by providing structural stiffness with carefully places material and direct load paths instead of beef. But that is just me.