1. What is a Torque Turn Calculator?

Definition: This calculator determines the torque required to achieve a specific pretension force in bolted joints based on the friction factor and bolt diameter.

Purpose: It helps engineers and technicians properly tighten bolts to ensure structural integrity and prevent joint failure.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( T \) — Torque (Newton-meters)
• \( k \) — Friction factor (dimensionless)
• \( F \) — Pretension force (Newtons)
• \( d \) — Bolt diameter (meters)

Explanation: The torque is calculated by multiplying the friction factor by the desired pretension force and the bolt diameter.

3. Importance of Torque Calculation

Details: Proper torque calculation ensures bolted joints are neither under-tightened (risking joint failure) nor over-tightened (risking bolt failure).

4. Using the Calculator

Tips: Enter the friction factor (default 0.2), pretension force in Newtons, and bolt diameter in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical friction factor (k) value?
A: For dry, unlubricated steel bolts, k is typically 0.2. Lubricated bolts may have k values of 0.1-0.15.

Q2: How do I determine the pretension force?
A: Pretension force is typically 60-75% of the bolt's proof load, which can be found in bolt specifications.

Q3: Why does bolt diameter affect torque?
A: Larger diameters create more rotational resistance, requiring more torque to achieve the same clamping force.

Q4: Should I account for thread pitch?
A: This simplified formula doesn't include thread pitch, which is acceptable for most standard applications.

Q5: How accurate is this calculation?
A: It provides a good estimate, but actual torque may vary due to surface conditions, lubrication, and other factors.