βš™οΈ Mechanical Design β€Ί Spring Calculator
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SpringCalc
Engineering Tool
Mechanical Design

Spring Selection
Calculator

Calculate spring rate, stress, deflection and verify spring suitability for compression, extension and torsion springs.

Spring Type
πŸ—œοΈ
Compression
Resists compressive force
↔️
Extension
Resists tensile / pull force
πŸ”„
Torsion
Resists rotational moment
Spring Diagram & Parameters
Spring Rate (k)
-N/mm
Enter parameters and calculate
Spring Index (C = D/d)
-
Recommended: 4 – 12
Max Torsional Stress
-MPa
0Safe
Detailed Results
Wahl Factor (Kw)-
Wire Length-
Solid Length-
Free Length-
Max Deflection-
Key Formulas
Spring Ratek = Gd⁴ / 8DΒ³Nₐ
Spring IndexC = D / d
Wahl FactorKw = (4Cβˆ’1)/(4Cβˆ’4) + 0.615/C
Max StressΟ„ = Kw Β· 8FD / Ο€dΒ³
DeflectionΞ΄ = F / k
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Spring Calculator: Compression Extension Torsion Spring Design Guide

Springs store and release mechanical energy. Correct design of compression, extension and torsion springs, spring constant, deflection, stress and natural frequency, is critical for product reliability. This calculator enables accurate spring design with a built-in material library.

πŸ“‹ How to Use This Calculator

  1. Select spring type, Compression, Extension or Torsion.
  2. Enter wire diameter (d), mean coil diameter (D) and number of active coils (n).
  3. Select material, music wire, chrome-silicon, stainless steel, etc.
  4. Enter applied load, spring rate, deflection, shear stress and safety factor will be calculated.

πŸ“ Formula & Working Principle

Spring Rate k = (G Γ— d⁴) / (8 Γ— DΒ³ Γ— n). Shear Stress Ο„ = (8 Γ— F Γ— D) / (Ο€ Γ— dΒ³) Γ— Kw. Natural Frequency f = (1/2Ο€) Γ— √(k/m). Where G = shear modulus, Kw = Wahl correction factor.

πŸ’‘ Worked Example

Music wire spring: d=2 mm, D=20 mm, n=10 active coils, G=79 GPa. k = 79000Γ—2⁴/(8Γ—20Β³Γ—10) = 1.975 N/mm. For 50 N load: Deflection = 50/1.975 = 25.3 mm.

❓ Frequently Asked Questions (FAQ)

Q: What is the spring index and what is the ideal value?

Spring Index C = D/d (mean coil dia Γ· wire dia). Ideal range: 6 to 12. C<4 β†’ difficult to manufacture. C>12 β†’ spring buckles and tangles easily.

Q: What is the difference between music wire and chrome-silicon?

Music wire (ASTM A228) is for general purpose, high tensile strength. Chrome-silicon (ASTM A401) is better for elevated temperature (up to 250Β°C) and high-stress cyclic applications.

Q: What is solid height?

The height when the spring is fully compressed and coils touch = n_total Γ— d. Always design with a minimum 10–15% travel gap above solid height.

Q: When does buckling occur?

Buckling risk increases when free length Γ· mean coil diameter > 4. Use a guide rod or sleeve to prevent this.

Q: How can spring fatigue life be improved?

Shot peening, stress-relieving heat treatment and pre-setting significantly improve spring fatigue life, especially in cyclic load applications.

Spring Calculator: Compression Extension Torsion Spring Design Guide

Springs store and release mechanical energy. Correct design of compression, extension and torsion springs, spring constant, deflection, stress and natural frequency, is critical for product reliability. This calculator enables accurate spring design with a built-in material library.