1. What is the Torque Equation?

The torque equation (τ = K × D × F) calculates the torque required to achieve a specific axial force (preload) in a fastener. It accounts for friction between threads and under the bolt head/nut.

2. How Does the Calculator Work?

The calculator uses the torque equation:

Where:

• \( \tau \) — Torque (Nm)
• \( K \) — Friction coefficient (unitless)
• \( D \) — Nominal diameter (m)
• \( F \) — Axial force (N)

Explanation: The equation shows that torque is directly proportional to both the friction coefficient and the bolt diameter, as well as the desired axial force.

3. Importance of Torque Calculation

Details: Proper torque calculation ensures fasteners are tightened correctly - enough to prevent loosening but not so much as to cause damage or failure.

4. Using the Calculator

Tips: Enter the friction coefficient (typically 0.1-0.3 for lubricated fasteners), bolt diameter in meters, and desired axial force in Newtons.

5. Frequently Asked Questions (FAQ)

Q1: What are typical K values?
A: For dry steel-on-steel, K≈0.2. Lubricated threads may have K≈0.1-0.15. Always consult specific fastener specifications.

Q2: Why is diameter important?
A: Larger diameter fasteners require more torque to achieve the same axial force due to the increased moment arm.

Q3: How accurate is this calculation?
A: It provides a good estimate but actual torque may vary due to surface finish, lubrication, and thread condition.

Q4: Should I use metric or imperial units?
A: The calculator uses metric (Nm), but you can convert inputs as needed (1 Nm = 8.8507 in-lb).

Q5: What about bolt strength?
A: Always ensure the calculated axial force doesn't exceed the bolt's proof load or yield strength.