Torque for a desired preload ( fasteners )


Bolted joints are one of the most common elements in construction and machine design. They consist of fasteners that capture and join other parts, and are secured with the mating of screw threads. (A fastener is a hardware device that mechanically joins or affixes two or more objects together). Typically, a bolt is tensioned (preloaded) by the application of a torque to either the bolt head or the nut. The preload developed in a bolt is due to the applied torque and is a function of the bolt diameter, length, the geometry of the threads and the coefficients of friction that exist in the threads and under the bolt head or nut.

Related formulas


TThe required torque (N*m)
KThe nut factor (usually 0.20) (dimensionless)
PpreThe desired preload (N)
dThe bolt diameter (m)