1. What is Bolt Force?

Bolt force is the axial force generated in a bolt when torque is applied during tightening. It's crucial for ensuring proper joint clamping force and preventing bolt failure or loosening.

2. How Does the Calculator Work?

The calculator uses the bolt force equation:

Where:

• \( Torque \) — Applied torque (N-m)
• \( Pitch \) — Thread pitch (m)
• \( Friction \) — Friction coefficient (decimal)
• \( Radius \) — Effective radius (m)

Explanation: The equation accounts for both the thread geometry (pitch) and friction effects in converting torque to axial force.

3. Importance of Bolt Force Calculation

Details: Proper bolt force ensures joint integrity, prevents leakage, and maintains structural stability. Under-tightening can lead to joint separation while over-tightening may cause bolt failure.

4. Using the Calculator

Tips: Enter torque in N-m, pitch in meters, friction coefficient (typically 0.1-0.2 for steel), and radius in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is typical friction coefficient for bolts?
A: For steel bolts, 0.12-0.18 is common. Higher for dry or rough surfaces, lower for lubricated threads.

Q2: How does pitch affect bolt force?
A: Finer pitch (smaller distance between threads) generates more axial force for the same torque.

Q3: What is the effective radius?
A: Typically the average of thread root and crest radii, often approximated as half the nominal diameter.

Q4: Why is friction important in bolt tightening?
A: Friction consumes 90% or more of applied torque. Small changes in friction can dramatically affect achieved bolt force.

Q5: Are there limitations to this calculation?
A: This is a simplified model. Actual force may vary due to surface finish, lubrication, thread form, and tightening speed.