Tightening torque information
In this app tightening torque is calculated with the following formula:
Where dm is thread friction diameter, µ1 is thread friction, Dk is bearing surface friction diameter, µ2 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, dm, is considered equivalent to pitch diameter.