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# Clamping force on a bolted joint

## Clamping force on a bolted joint

(OP)
Given the initial torque ( in lb ) imparted upon a UNC 4-40x 1/2 Type II Cross Recessed Pan Head machine screw and nut, how can I figure out the clamping force imposed upon the bolted joint? I have the equations to find the bolt preload given an initial torque, but not the clamping force. To add insult to injury, the screw/bolt system has several bushings in it. Is this something that I need to consider when determining the actual compressive force on the bolted joint? Lastly, I have heard mention of a book called the "bolting bible"; does anybody know of this book or where it can purchased?

### RE: Clamping force on a bolted joint

Check out www.boltscience.com

William H. Bernhart, P.E.

I work as a development engineer for AMP - Tyco Electronics located near Harrisburg, PA. I help design interconnections and electrical connectors for aerospace applications.

### RE: Clamping force on a bolted joint

I work at Rotek Inc. in Aurora Ohio and this is
a common problem to large bearings which are bolted
in place.  The clamping force, turning angle, torque
are related to the rated tensile strength of these
bolts posted by most bolt manufacturer's.
They are generally posted by the grade of bolt, material,
etc.

### RE: Clamping force on a bolted joint

I think you need to look at a good machine design textbook.

"Machine Design-Theory and Practice" Deutchman, Michels, and Wilson

"Mechanical Engineering Design" Shigley and Mitchell

"Design of Machine Elements" Spotts

Or you might try the Machinery Handbook by Industrial Press Inc

The clamping force will also depend on the materials being clamped in a bolted
connection.

Don Leffingwell
dleffingwell@snet.net

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