The In-Situ Balancing Process: What the Specialist Does On Your Equipment

Stage 1: Preparation and preliminary diagnostics

What the specialist does:

Equipment inspection:

• Visual inspection of the rotor, housing and mountings
• Checking access to the correction planes (where balance weights can be fitted)
• Assessing the technical condition

Preliminary vibration diagnostics:

• Measuring the overall vibration level
• Establishing whether imbalance is the main cause of the vibration
• Identifying related problems (misalignment, bearings, loose mountings)

Technical-condition check:

• Condition of the bearings (no play, no overheating)
• Fastening of the rotor and the unit to the foundation
• Absence of cracks and deformation

Stage 2: Installing the measuring equipment

What the specialist uses:

• A portable vibration analyser (for example, the Balanset-1A) — a two-channel instrument for measuring vibration
• Vibration sensors (2 off) — fitted to the bearing housings
• A laser tachometer — measures the rotational speed and the phase of the vibration
• A laptop with the calculation software
• Trial weights of known mass
• Tools for fitting correction weights (welder, drill, spanners)

Setup time: 15-30 minutes.

Stage 3: Measurement and calculations

Balancing is carried out using the influence-coefficient method (the 3-run method for two-plane balancing).

The procedure:

Measurement 1 (no weight):

• The machine is run up to operating speed
• The instrument measures the initial vibration and its phase
• This data serves as the baseline for all the calculations

Measurement 2 (with a trial weight in plane 1):

• The machine is stopped
• The specialist fits a trial weight of known mass
• The machine is run up again
• The change in vibration is measured
• The trial weight is removed

Duration of this stage: 1-2 hours (including 3 machine run-ups).

Stage 4: Correcting the imbalance

Fitting the correction weights:

The specialist fits permanent weights at the calculated positions. The fixing methods depend on the rotor design:

• Welding: Welding on small metal plates (the most reliable and durable method)
• Bolted connection: Where threaded holes are available or can be drilled
• Special clamps: For certain types of rotor
• Removing material: Drilling holes on the "heavy" side (less preferred)

The weights are fitted precisely at the calculated positions. The accuracy of fitting is critical to the result.

Duration of this stage: 30-60 minutes.

Stage 5: Verification measurement and quality check

Checking the result:

1. The machine is run up one final time
2. The residual vibration is measured
3. The specialist confirms that the vibration has fallen to acceptable values

Criteria for a successful balance:

• Vibration has been reduced 5-10 times compared with the original value
• The residual imbalance is within tolerance per ISO 21940
• The vibration level is in zone A or B per ISO 10816
• The machine runs smoothly, without shocks

Duration of this stage: 20-30 minutes.

What you receive after balancing

Documentation:

• A balancing report stating:
  • The initial vibration level (before balancing)
  • The vibration level achieved (after balancing)
  • The correction masses fitted and their positions
  • Compliance with the ISO 21940 standards
• Recommendations for further operation
• A warranty on the work carried out (typically 3-6 months)

Total time for the work:

A full balancing cycle usually takes 2-4 hours, depending on the complexity of the equipment:

• A small fan or pump: 2-3 hours
• A large induced-draught fan or crusher: 3-4 hours
• Complex equipment: up to one working day