1. What is Bolt Clamp Load?

Bolt clamp load (also known as preload) is the tension created in a bolt when it is tightened. This force holds joint members together and is critical for the integrity of bolted connections in various engineering applications.

2. How Does the Calculator Work?

The calculator uses the bolt clamp load formula:

Where:

• \( F \) — Bolt clamp load (N)
• \( T \) — Applied torque (N m)
• \( K \) — Torque coefficient (dimensionless)
• \( D \) — Bolt nominal diameter (m)

Explanation: The formula calculates the axial force (clamp load) generated in a bolt when a specific torque is applied, accounting for the torque coefficient and bolt diameter.

3. Importance of Bolt Clamp Load Calculation

Details: Proper bolt clamp load is essential for joint integrity, preventing loosening, maintaining seal pressure, and ensuring structural stability. Under-tightening can lead to joint failure, while over-tightening may cause bolt fracture.

4. Using the Calculator

Tips: Enter torque in Newton-meters (N m), K factor (typically 0.2 for dry steel, 0.15-0.18 for lubricated), and bolt diameter in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical K factor value?
A: K factor typically ranges from 0.12 to 0.30 depending on surface conditions, lubrication, and thread type. 0.2 is commonly used for dry, unlubricated steel connections.

Q2: Why is clamp load important in bolted joints?
A: Proper clamp load ensures the joint remains tight under operating conditions, prevents leakage in sealed connections, and maintains structural integrity under vibration and dynamic loads.

Q3: How accurate is the torque-tension relationship?
A: The relationship is approximate with ±25% accuracy typically. For critical applications, direct tension measurement or ultrasonic methods provide more accurate results.

Q4: What affects the K factor value?
A: Surface finish, lubrication, thread type, material combination, and washers all influence the K factor value.

Q5: When should I use more precise methods?
A: For critical applications, safety-critical joints, or when precise preload is required, consider using torque-angle method, direct tension indicators, or ultrasonic measurement.