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### Bolt Torque from Thread Pitch Calculator

**Fastener and Screw / Bolt Design Formula Design Data
Strength of Materials **

Fastener Relation Between Torque, Thread Pitch and Clamping Force Formula and Calculator

Relationship between the applied tightening torque and bolt preload F_{f}

Equation 1

*T = F _{f} · { d_{2} / 2 ( µ / cosα + tanβ ) + µ_{n} d_{n} / 2 }*

Alternatively

Equation 2

* F _{f} = T / { d_{2} / 2 ( µ / cosα + tanβ ) + µ_{n} d_{n} / 2 } *

Figure 1 Drawing nomenclature

*Figure 2 Drawing nomenclature *

Where:

*T *= torque, N-mm*
F *= axial tension, N

*= Pitch diameter, mm*

d

d

_{2}*= Friction coefficient of threaded portion*

µ

µ

*µ*= Friction coefficient of bearing portion

_{n}*Half angle of screw thread, ISO screw 30°*

α =

α =

*Lead Angle*

β =

β =

Reference:

"Theory and calculation of threaded fasteners" Akira Yamamoto (Yokendo Co., Ltd)

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