1. What is the Metric Screw Torque Equation?

The metric screw torque equation calculates the tightening torque required for threaded fasteners. It's essential for proper bolt tensioning and preventing joint failure in mechanical assemblies.

2. How Does the Calculator Work?

The calculator uses the torque equation:

Where:

• \( K \) — Torque coefficient (dimensionless)
• \( D \) — Nominal bolt diameter (meters)
• \( F \) — Axial bolt force (Newtons)

Explanation: The equation accounts for the relationship between applied torque and bolt tension, with K-factor representing friction and geometric factors.

3. Importance of Torque Calculation

Details: Proper torque calculation ensures sufficient clamping force without overstressing the fastener or joint components. Critical for structural integrity and safety.

4. Using the Calculator

Tips: Enter K-factor (typically 0.2 for dry steel), bolt diameter in meters, and desired axial force in Newtons. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical K-factor values?
A: Common values range from 0.15-0.25 (0.2 for dry steel, 0.15-0.18 for lubricated steel, higher for rough surfaces).

Q2: How accurate is this calculation?
A: Provides good estimates but actual torque may vary ±25% due to friction variations. Critical applications require experimental verification.

Q3: Should I use thread or head diameter for D?
A: Use nominal thread diameter (major diameter) for metric screws.

Q4: What affects the K-factor?
A: Surface finish, lubrication, thread pitch, and material combinations all influence the K-factor value.

Q5: How does this relate to bolt tension?
A: The torque creates tension in the bolt which generates clamping force. About 90% of torque overcomes friction.