1. What is Torsional Spring Rate?

The torsional spring rate (k) measures the spring's resistance to twisting, expressed in torque per unit angle (N·m/rad). It's a crucial parameter in designing springs for rotational applications.

2. How Does the Calculator Work?

The calculator uses the torsional spring rate equation:

Where:

• \( k \) — Torsional spring rate (N·m/rad)
• \( E \) — Modulus of elasticity (Pa)
• \( d \) — Wire diameter (m)
• \( D \) — Mean coil diameter (m)
• \( N \) — Number of active turns

Explanation: The equation shows that spring rate increases with higher modulus and wire diameter (to the 4th power), but decreases with larger coil diameter and more turns.

3. Importance of Spring Rate Calculation

Details: Accurate spring rate calculation is essential for proper functioning in applications like clothespins, mouse traps, and various mechanical assemblies requiring rotational force.

4. Using the Calculator

Tips: Enter all values in consistent units (meters for lengths, Pascals for modulus). Ensure wire diameter is significantly smaller than mean diameter for valid results.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical modulus value for spring steel?
A: For common spring steels, E ≈ 200 GPa (200 × 10⁹ Pa).

Q2: How does wire diameter affect spring rate?
A: Since d is raised to the 4th power, small changes in wire diameter have large effects on spring rate.

Q3: What's the difference between active and total turns?
A: Active turns are those free to deflect. Total turns include inactive ends. Use active turns in calculations.

Q4: Can this be used for non-circular wire?
A: No, this equation is specifically for round wire. Different equations exist for rectangular wire.

Q5: How accurate is this calculation?
A: It provides good estimates for standard spring designs but may need adjustment for extreme geometries.