1. What is Fastener Clamp Load?

Fastener clamp load (F) is the axial force created in a fastener when it is tightened. This force holds joint members together and creates a seal between them, preventing loosening under vibration and maintaining joint integrity.

2. How Does the Calculator Work?

The calculator uses the fastener clamp load formula:

Where:

• \( F \) — Fastener clamp load (N)
• \( T \) — Applied torque (Nm)
• \( K \) — Torque coefficient (dimensionless)
• \( D \) — Nominal diameter (m)

Explanation: The formula calculates the axial clamping force generated when torque is applied to a fastener, considering the torque coefficient and fastener diameter.

3. Importance of Fastener Clamp Load Calculation

Details: Accurate clamp load calculation is crucial for proper joint design, ensuring sufficient preload to prevent joint separation while avoiding over-tightening that could damage fastener or joint components.

4. Using the Calculator

Tips: Enter torque in Nm, torque coefficient (typically 0.15-0.25 for lubricated steel fasteners), and diameter in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical torque coefficient value?
A: For unlubricated steel fasteners, K is typically 0.15-0.25. Lubricated fasteners may have lower values around 0.10-0.15.

Q2: Why is clamp load important in bolted joints?
A: Proper clamp load ensures joint integrity, prevents loosening, maintains sealing pressure, and distributes loads evenly across joint members.

Q3: How does friction affect clamp load?
A: Higher friction (higher K value) reduces clamp load for a given torque, as more torque is consumed overcoming friction rather than generating tension.

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

Q5: When should direct tension measurement be used instead?
A: For critical applications, direct measurement using ultrasonic extensometers or strain gauges provides more accurate clamp load determination.