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Bolt Clamping Force Calculator

Clamping Force Formula:

\[ F = \frac{T}{K \times d} \]

Where:

  • \( F \) = Clamping Force (pounds)
  • \( T \) = Torque (ft-lb)
  • \( K \) = Nut Factor (dimensionless)
  • \( d \) = Bolt Diameter (inches)

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inches

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1. What is Bolt Clamping Force?

The bolt clamping force is the compressive force that a bolt exerts on the joint when tightened. It's crucial for maintaining joint integrity and preventing loosening under load.

2. How Does the Calculator Work?

The calculator uses the clamping force formula:

\[ F = \frac{T}{K \times d} \]

Where:

Explanation: The formula shows that clamping force is directly proportional to torque and inversely proportional to both the nut factor and bolt diameter.

3. Importance of Clamping Force

Details: Proper clamping force ensures joint integrity, prevents bolt loosening from vibration, and maintains proper gasket compression in sealed joints.

4. Using the Calculator

Tips: Enter torque in ft-lb, nut factor (default is 0.2 for dry, unlubricated bolts), and bolt diameter in inches. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical nut factor (K) value?
A: For dry, unlubricated bolts: ~0.2. For lubricated bolts: ~0.15-0.18. Highly lubricated: as low as 0.1.

Q2: Why does bolt diameter affect clamping force?
A: Larger diameter bolts distribute the torque over a larger radius, resulting in less axial force for the same torque.

Q3: How accurate is this calculation?
A: It provides a good estimate but actual values vary due to friction, lubrication, surface finish, and bolt condition.

Q4: What affects the nut factor?
A: Thread condition, lubrication, surface finish, and washers all influence the nut factor.

Q5: Should I use this for critical applications?
A: For critical joints, consult engineering specifications or perform actual tension measurements.

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