1. What is the Metric Bolt Torque Equation?

The metric bolt torque equation calculates the tightening torque required to achieve a specific preload in a bolted joint. It's essential for proper fastener installation and joint integrity.

2. How Does the Calculator Work?

The calculator uses the torque equation:

Where:

• \( T \) — Torque (Nm)
• \( K \) — Torque coefficient (dimensionless)
• \( D \) — Bolt diameter (mm)
• \( P \) — Preload (N)

Explanation: The equation accounts for the relationship between applied torque and the resulting bolt tension, considering friction and geometric factors.

3. Importance of Torque Calculation

Details: Proper torque calculation ensures bolted joints are neither under-tightened (leading to loosening) nor over-tightened (which can cause bolt failure).

4. Using the Calculator

Tips: Enter the torque coefficient (typically 0.15-0.2 for dry steel), bolt diameter in millimeters, and desired preload in newtons.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical torque coefficient value?
A: For dry steel fasteners, K is typically 0.15-0.2. Lubricated fasteners may have K values as low as 0.1.

Q2: Why is bolt diameter important?
A: Larger diameter bolts require more torque to achieve the same preload due to increased friction and leverage.

Q3: How accurate is this calculation?
A: This provides an estimate. Actual torque required may vary due to surface finish, lubrication, and other factors.

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

Q5: Should this be used for critical applications?
A: For critical joints, consult engineering specifications or perform actual tension testing.