## Tightening torque information

In this app tightening torque is calculated with the following formula:

Where d_{m} is thread friction diameter, µ_{1 }is thread friction,_{ }D_{k }is bearing surface friction diameter,_{ }µ_{2 }is bearing surface friction and P is pitch. There are three terms within the brackets, two describe the part of applied torque that is required to overcome the friction and one how the pitch transforms torque to preload.

D = Bearing surface outer diameter

d = Bearing surface inner diameter

Thread friction diameter, d_{m}, is considered equivalent to pitch diameter.