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Preloading Torque Calculator

Torque Formula:

\[ T = k \times F \times d \]

N
m
Nm

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1. What is a Preloading Torque Calculator?

Definition: This calculator estimates the torque required to achieve a specific preload force in a bolted joint.

Purpose: It helps engineers and technicians determine the appropriate tightening torque for bolts to ensure proper joint integrity.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ T = k \times F \times d \]

Where:

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

3. Importance of Torque Calculation

Details: Proper torque calculation ensures bolted joints are neither under-tightened (leading to joint failure) nor over-tightened (which can damage components).

4. Using the Calculator

Tips: Enter the friction factor (default 0.2), desired 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 0.15-0.18.

Q2: How do I determine the pretension force?
A: Pretension force is typically 60-75% of the bolt's proof load, which depends on bolt material and grade.

Q3: Why does bolt diameter affect torque?
A: Larger diameter bolts require more torque to achieve the same clamping force due to increased friction radius.

Q4: Should I account for thread pitch?
A: The basic formula doesn't include thread pitch, but more advanced calculations might consider it for precision.

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

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