Ideambox
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TOOL IDB-MEC-004
Screw torque & preload

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Engineering tools are available only on desktop screens.

Screw torque & preload

Recommended torque and preload for metric screws by grade. K-factor from your friction condition.

Bolt & preload — % yield
Torque T = — Preload — kN Preload utilisation vs yield — % 70% typ 85% max
20%70% typical85% max
Engineering notes

Formula

  • Preload: Fp = util · As · σy
  • Torque: T = K · D · Fp

Practical guidance

  • Tolerance: ±25% hand driver, ±10% torque wrench, ±5% calibrated tool.
  • Soft mating part: cut preload 30–50%.
  • Vibration: use thread-locker instead of higher torque.

Result

Live