Is T=KFd an ISO 16047 formula?

No. It is an empirical nut-factor model. ISO 16047:2005 plus Amendment 1:2012 specifies torque/clamp-force test conditions that can provide assembly-specific data.

Does this calculator choose preload or K?

No. Target clamp force must come from joint design and K from qualified assembly-specific test data or procedure.

Does the displayed K range represent tool accuracy?

No. It is only sensitivity to user-entered K values. Tool uncertainty and clamp-force scatter require a validated assembly procedure.

Empirical sensitivity tool

User-Data Bolt Torque Sensitivity

Evaluate T=K·F·d for a target clamp force and assembly-specific nut factor supplied by the user. This page does not select bolt grade, preload, lubrication or tightening procedure.

Empirical K modelISO 16047 test contextNot VDI 2230 design

Empirical torque sensitivity

Nominal T=KFd

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Torque at lower K

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Torque at upper K

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K sensitivity span

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Empirical nut-factor arithmetic

T [N·m] = K · F [kN] · d [mm]

The numerical equality follows because kN·mm equals N·m. K is dimensionless. The equation is a compact empirical correlation, not a universal ISO or VDI formula.

ISO 16047 test context

ISO 16047:2005 s spletno stranjo . Amendment 1:2012 specifies conditions for torque/clamp-force testing of threaded fasteners. It does not justify generic K values for “dry”, oil, PTFE or anti-seize. Use measured data representative of the actual assembly.

VDI 2230 design boundary

VDI 2230 Part 1:2015 covers systematic joint design including minimum clamp load, preload changes, assembly preload, torque and strength verification. This five-input sensitivity calculation does not claim VDI conformity.

Not modelled: thread/bearing friction separation, geometry, tightening scatter distribution, torsion during tightening, embedment, relaxation, external loading, fatigue, temperature, gasket behaviour, prevailing torque, sequence or tool calibration.