Spring Selection Calculator
Find optimal spring stiffness for target resonant frequency
Calculation Parameters
Based on ISO 22705-1:2021 and vibration isolation principles
Spring Selection Results
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Spring Selection Guidelines:
How the Calculator Works
Target Frequency Design
Required stiffness for target natural frequency:
where fn is target frequency and m is system mass
Vibration Isolation
For effective isolation, natural frequency should be:
where ff is forcing frequency. Lower is better for isolation.
Transmissibility
Force transmission ratio:
T < 1 means isolation, T > 1 means amplification
Spring Arrangements
- Parallel: k_total = n × k_individual
- Series: k_total = k_individual / n
- Mixed: Calculate based on specific configuration
Design Considerations
- Include safety factor for manufacturing tolerances
- Consider spring surge frequency (should be > 13×fn)
- Account for spring weight if significant
- Check for coil binding at maximum deflection
- Verify buckling stability for long springs
Common Applications
- HVAC Equipment: 3-6 Hz typical
- Pumps/Motors: 5-10 Hz typical
- Sensitive Equipment: 1-3 Hz for floor vibration isolation
- Vehicle Suspension: 1-2 Hz for comfort
Spring Material Properties
| Material | Shear Modulus (GPa) | Applications |
|---|---|---|
| Music Wire | 81.7 | High stress, general purpose |
| Stainless 302 | 69.0 | Corrosion resistance |
| Chrome Silicon | 77.2 | High temperature |
📘 Spring Selection Calculator
Selects spring parameters for specified mass and required natural frequency for vibration isolation.
Principle: For isolation from frequency f, natural frequency fn should be < f/√2, ideally < f/3.
💼 Applications
- Roof Fan: 380 kg, 1450 RPM = 24.2 Hz. Goal: 92% reduction (TR=0.08). Required fn: 24.2/4 = 6 Hz. k = 54000 N/m total. 4 mounting points → 13500 N/m each. Selected AMC-140 (14 kN/m). Result: fn=6.2 Hz, vibration 8.5→0.7 mm/s ✓
- Diesel Generator: 4200 kg, variable 900-1500 RPM. Goal: isolate entire range. fn = 5 Hz (below all). k = 415 kN/m. 8 mounts → 52 kN/m each. AMC-250 (50 kN/m) with dampers for startup resonance pass.
- Precision Table: 650 kg. External vibration: 5-50 Hz. Goal: isolate all. fn = 2 Hz. k = 10.3 kN/m. 4 pneumatic mounts with auto-leveling. Damping 0.1-0.2 critical.
Isolation Effectiveness:
Transmissibility TR = 1/|1-(f/fn)²|. For TR<1 need f/fn>√2. Best: f/fn>3 gives TR=0.1 (90% reduction).
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