Balancing Platform Design Calculator • Portable balancer, vibration analyzer "Balanset" for dynamic balancing crushers, fans, mulchers, augers on combines, shafts, centrifuges, turbines, and many others rotors Balancing Platform Design Calculator • Portable balancer, vibration analyzer "Balanset" for dynamic balancing crushers, fans, mulchers, augers on combines, shafts, centrifuges, turbines, and many others rotors

Balancing Platform Design Calculator

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Balancing Platform Design Calculator

Complete design tool for spring-mounted rotor balancing machines

Platform Design Parameters

Based on ISO 21940, ISO 2041, and balancing machine design principles


Rotor Parameters







RPM


RPM

Platform Configuration





Design Constraints





Platform Design Results

Spring Requirements

Total Required Stiffness:
—
Individual Spring Stiffness:
—
Spring Wire Diameter (estimated):
—

Dynamic Characteristics

Platform Natural Frequency:
—
Frequency Ratio at Min Speed:
—
Frequency Ratio at Max Speed:
—
Static Deflection:
—

Performance Predictions

Transmissibility at Min Speed:
—
Transmissibility at Max Speed:
—
Minimum Detectable Unbalance:
—

Design Recommendations:

Balancing Platform Design Theory

Soft vs Hard Bearing Machines

Soft Bearing: Platform natural frequency < 30% of minimum rotor speed

  • Better sensitivity to unbalance
  • Wider speed range capability
  • Requires less massive foundation
  • More susceptible to external vibration

Hard Bearing: Platform natural frequency > 3× maximum rotor speed

  • More stable measurements
  • Better for production balancing
  • Less sensitive to rotor changes
  • Requires very stiff supports

Natural Frequency Selection

fn = (1/2π) × √(k_total / m_total)

For soft bearing: fn < 0.3 × (RPMmin / 60)

For hard bearing: fn > 3 × (RPMmax / 60)

Spring Stiffness Calculation

k_total = (2π × fn)² × (m_rotor + m_platform)
k_individual = k_total / n_springs (for parallel arrangement)

Sensitivity Considerations

Platform sensitivity depends on:

  • Mass ratio (platform/rotor)
  • Natural frequency separation
  • Damping level
  • Sensor placement and type

Critical Design Checks

  • Spring Surge: Spring natural frequency > 13× platform frequency
  • Static Deflection: Must not exceed spring solid height
  • Lateral Stability: Prevent platform rocking modes
  • Foundation Isolation: Consider double isolation if needed

Typical Applications

Rotor Type Speed Range Platform Type Typical fn
Small rotors 1000-10000 RPM Soft bearing 2-5 Hz
Electric motors 600-3600 RPM Soft bearing 1-3 Hz
Turbines 3000-20000 RPM Soft bearing 5-15 Hz
Crankshafts 300-2000 RPM Hard bearing 100+ Hz

Usage Examples & Value Selection Guide

Example 1: Electric Motor Balancing Machine

Scenario: Design a balancing platform for electric motors up to 50 kg, operating at 1500-3000 RPM

  • Rotor Mass: 50 kg (maximum motor weight)
  • Platform Mass: 100 kg (2× rotor mass for stability)
  • Speed Range: 1500-3000 RPM
  • Platform Type: Soft bearing (better sensitivity)
  • Springs: 4 springs at corners
  • Damping: Light (ζ = 0.05)
  • Max Deflection: 25 mm
  • Result: fn ≈ 6.25 Hz, spring stiffness ≈ 5.8 kN/m each
Example 2: Large Turbine Rotor

Scenario: High-speed turbine rotor, 200 kg, 10000-20000 RPM

  • Rotor Mass: 200 kg
  • Platform Mass: 300 kg (1.5× for heavy rotors)
  • Speed Range: 10000-20000 RPM
  • Platform Type: Soft bearing
  • Springs: 6 springs (hexagonal for stability)
  • Damping: Moderate (ζ = 0.1)
  • Max Deflection: 15 mm (stiffer for precision)
  • Result: fn ≈ 41.7 Hz, very stiff springs needed

How to Choose Values

Platform Mass Selection
  • Light rotors (< 50 kg): Platform mass = 2-3× rotor mass
  • Medium rotors (50-200 kg): Platform mass = 1.5-2× rotor mass
  • Heavy rotors (> 200 kg): Platform mass = 1-1.5× rotor mass
  • Rule: Heavier platform = more stable but less sensitive
Platform Type Selection
  • Soft Bearing: Choose when:
    • Wide speed range needed
    • High sensitivity required
    • Research/development applications
    • Variable rotor types
  • Hard Bearing: Choose when:
    • Production balancing
    • Single speed operation
    • Heavy rotors
    • Minimal foundation available
Spring Configuration
  • 3 springs (triangular): Minimum stability, light rotors only
  • 4 springs (rectangular): Most common, good for rectangular platforms
  • 6 springs (hexagonal): Better stability for large/heavy rotors
  • 8-12 springs: Very large platforms or special requirements
Damping Requirements
  • No damping: Rigid rotors, far from resonance
  • Light (ζ = 0.05): Standard choice for most applications
  • Moderate (ζ = 0.1): When passing through resonance
  • Heavy (ζ = 0.2): Flexible rotors or special requirements
Maximum Deflection
  • 10-15 mm: High precision, small rotors
  • 20-30 mm: Standard applications
  • 30-50 mm: Large/heavy rotors
  • Rule: Must not exceed 80% of spring free length

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📘 Balancing Platform Calculator

Designs balancing platform for two-plane rotor balancing. Calculates platform natural frequency, spring stiffness, and sensitivity per ISO 1940-1.
Soft bearing: fn < 0.3 × fmin | Hard bearing: fn > 3 × fmax

💼 Applications

  • Fan Balancing (Soft): Rotor 45 kg + platform 35 kg = 80 kg. Speed: 1480 RPM = 24.7 Hz. Required fn < 0.3×24.7 = 7.4 Hz. Designed: fn = 6 Hz. Springs: 4 × 22 kN/m. Sensitivity: detects 0.5 g·mm/kg unbalance.
  • Turbocharger (Hard): Rotor 12 kg, 24000 RPM = 400 Hz. Required fn > 3×400 = 1200 Hz. Very stiff platform or rigid stand. Accelerometer-based measurement.
  • Pump Rotor (Soft): 185 kg rotor, 2980 RPM. Platform: 95 kg. fn = 4.2 Hz. Deflection: 8 mm. Damping: moderate (ζ=0.1). Detects 2 g·mm/kg (G2.5 class).

Platform Types:

Soft Bearing: Low fn. Large deflection. Measures relative rotor vibration. Good for all speeds including variable.

Hard Bearing: High fn. Stiff structure. Measures absolute vibration. Good for fixed speed, compact design.

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