1. What is the Bolt Torque Formula?

The bolt torque formula calculates the torque required to achieve a specific preload in a bolted joint. It's essential for ensuring proper clamping force and preventing joint failure in mechanical assemblies.

2. How Does the Calculator Work?

The calculator uses the bolt torque formula:

Where:

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

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

3. Importance of Bolt Torque Calculation

Details: Proper bolt torque calculation is crucial for ensuring joint integrity, preventing loosening under vibration, avoiding over-tightening that could damage threads, and maintaining consistent clamping force across multiple bolts.

4. Using the Calculator

Tips: Enter the torque coefficient (typically 0.15-0.25 for lubricated bolts), desired axial force in Newtons, and nominal bolt diameter in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for torque coefficient K?
A: For standard bolts, K typically ranges from 0.15 to 0.25, with 0.2 being a common default value for lubricated bolts.

Q2: How does lubrication affect the torque coefficient?
A: Lubrication reduces friction, which lowers the torque coefficient. This means less torque is required to achieve the same preload force.

Q3: Why is accurate bolt torque important?
A: Proper torque ensures adequate clamping force without exceeding the bolt's yield strength, preventing joint failure and maintaining structural integrity.

Q4: What factors influence the torque coefficient?
A: Surface finish, lubrication, thread type, material combination, and washers all affect the torque coefficient value.

Q5: Should torque values be verified after tightening?
A: Yes, critical applications often require torque verification using calibrated torque wrenches or other measurement methods to ensure proper installation.