How do you specify a bolt torque?
DETERMINING TORQUE The general equation for bolt load based on applied torque is T = KFiDb where K = torque coefficient. K is a function of the coefficients of friction and collar friction in the joint, and these are based on variables such as surface finish, coatings, and so on.
How to calculate the tightening torque of bolts?
The formula that expresses the relationship between the load in a bolt and applied torque is: K is the coefficient of friction. Your coefficient will depend on the material of your bolt/nut, the type of lubrication (or, rarely, the lack of lubrication) and the size of the bolt. The nominal bolt diameter is d in this equation.
How does a torque wrench know when to stop?
Some torque wrenches require constant reading of the torque indicator, so that you know when to stop twisting the bolt. Some have a dial to set the required torque, but the indicator doesn’t stop applying force automatically when torque is reached. They may have a visual signal such as a digital reading or an audible beep or click.
What’s the best way to determine a torque specification?
There are two ways to come up with a torque specification: “The right way and the wrong way,” quips David Archer, principal engineer at Peak Innovations Engineering, a consulting firm specializing in bolted joint design and analysis.
Which is the correct formula for torque and tension?
Accepted formulae relating torque and tension, based on many tests are: M = P x D M = torque lbf.ft 60 P = bolt tension lbf D = bolt dia.ins . Or for metric sizes: M = P x D M = torque N.m 5000 P = bolt tension Newtons D = bolt dia. mm These formulae may be used for bolts outside the range of the tables overleaf.
When do you use torque to tighten a bolt?
The bolt is tightened until the desired P (load) is indicated by the tension indicating device. The tightening torque required to achieve the desired tension is the actual tightening torque that should be used for that given application.
Is the torque of a fastener a direct indication of tension?
In developing this information, Fastenal has made a determined effort to present its contents accurately. Extreme caution should be used when using a formula for torque/ tension relationships. Torque is only an indirect indication of tension. Under/over tightening of fasteners can result in costly equipment failure or personal injury. NOTES:
What is the formula for target tightening torque?
The basic formula T = K x D x P stated earlier takes these factors into account and provides users with a starting point for establishing an initial target tightening torque. Target tighten torque (the result of this formula is in inch pounds, dividing by 12 yields foot pounds
Which is the best way to determine torque?
The best way to determine correct torque is through experimentation under actual assembly conditions. Other methods of achieving specific Clamp Load are: Turn-of-the-Nut. Specific Tension can be accurately correlated to the amount of rotation of a fastener once the parts of an assembly have been brought together. Direct Tension Indicator.