1. What is the Bolt Torque Formula?

The bolt torque formula (T = K × F × D) calculates the torque required to achieve a specific preload in a bolted joint. It's essential for proper fastener installation in mechanical engineering and construction applications.

2. How Does the Calculator Work?

The calculator uses the bolt torque formula:

Where:

• \( T \) — Bolt torque (Nm)
• \( K \) — Torque coefficient (dimensionless)
• \( F \) — Preload force (N)
• \( D \) — Nominal diameter (m)

Explanation: The formula accounts for the relationship between applied torque, friction coefficient, desired preload, and bolt size.

3. Importance of Bolt Torque Calculation

Details: Proper bolt torque calculation is crucial for joint integrity, preventing loosening, avoiding over-tightening, and ensuring safety in mechanical assemblies.

4. Using the Calculator

Tips: Enter torque coefficient (typically 0.15-0.25 for standard bolts), preload force in Newtons, and nominal diameter in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical K value for standard bolts?
A: For standard unlubricated bolts, K typically ranges from 0.15 to 0.25. Lubricated bolts may have values as low as 0.10.

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

Q3: Why is proper bolt torque important?
A: Correct torque ensures proper clamping force, prevents joint failure, avoids thread damage, and maintains structural integrity.

Q4: What factors affect the K value?
A: Surface finish, lubrication, thread condition, and material combinations all influence the torque coefficient.

Q5: Should this formula be used for critical applications?
A: For critical applications, additional factors like temperature, vibration, and fatigue should be considered, and professional engineering consultation is recommended.