Setting up a dynamic balancing programme
A dynamic balancing programme is a structured approach to correcting mass imbalance in rotating components such as fans, rotors and impellers, either on a balancing machine or in place on the running machine. It defines acceptable balance grades, balancing methods and records, so imbalance-driven vibration is controlled rather than tolerated.
What it is
Balancing redistributes or removes mass on a rotor so its mass centreline coincides with its rotational axis, eliminating the once-per-revolution force that imbalance creates. A programme sets the balance quality grade appropriate to each machine type, decides which items are balanced in a shop and which are trimmed in place, and keeps a record of correction weights and residual imbalance.
Why it is done
Imbalance produces vibration that loads bearings and structures and accelerates wear, and it is a common cause of high vibration on fans and pumps after refurbishment or fouling. Without a programme, balancing is done reactively and to no defined standard, so machines are returned to service still vibrating. A programme ties balance quality to a recognised grade and keeps machines smooth across their life.
How it is done
Each rotating asset is assigned a balance grade suited to its type and speed. Shop items are balanced on a calibrated machine across one or two planes; large or assembled machines are balanced in place using a vibration analyser to find the heavy spot and trial weights to calculate the correction. Final residual imbalance is verified against the chosen grade and recorded, and in-service items are rechecked when fouling or erosion is suspected.
- Assign balance grades
- Choose shop or in-place
- Measure heavy spot
- Apply trial weights
- Verify residual
- Record correction
What to watch for
Balancing a rotor that is actually bent, cracked or fouled simply masks the real fault and the vibration returns. Single-plane balancing of a component that needs two planes, and failing to clean fouling before balancing a fan, are the errors that produce short-lived results.
Related practices
Transitioning to condition-based maintenance
Rolling out reliability-centred maintenance
Running an asset criticality ranking exercise
Related topics
Vibration Analysis · Condition Monitoring · P-F Curve
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