1. What is Bolt Torque Calculation?

Bolt torque calculation determines the rotational force needed to achieve a specific preload (clamping force) in a bolted joint. Proper torque ensures joint integrity without damaging the fastener or components.

2. How Does the Calculator Work?

The calculator uses the bolt torque formula:

Where:

• \( T \) — Torque (Nm)
• \( K \) — Torque coefficient (dimensionless)
• \( F \) — Desired preload (N)
• \( D \) — Nominal diameter (m)

Explanation: The torque coefficient accounts for friction and other factors that affect the relationship between applied torque and achieved preload.

3. Importance of Proper Bolt Torque

Details: Correct bolt torque is critical for joint safety, preventing loosening from vibration, avoiding thread damage, and ensuring proper sealing in pressurized applications.

4. Using the Calculator

Tips: Enter the torque coefficient (typically 0.15-0.25 for lubricated steel), desired preload in newtons, and nominal diameter in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical torque coefficient value?
A: For unlubricated steel fasteners, K is typically 0.20-0.25. For lubricated fasteners, K can be 0.15-0.20.

Q2: How do I determine the required preload?
A: Preload is typically 60-75% of the bolt's proof load, which depends on bolt material, grade, and size.

Q3: Does this formula work for all bolt types?
A: This is a simplified formula that works well for standard bolts. Special fasteners may require more complex calculations.

Q4: Why is friction important in torque calculation?
A: Up to 90% of applied torque can be consumed by overcoming friction, with only about 10% actually creating clamp force.

Q5: When should I use a torque wrench?
A: Always use a calibrated torque wrench for critical applications to ensure proper preload and joint integrity.