Imbalance correction methods: welding, drilling or weights?
Once the vibration analyser has calculated the required correction mass and the angle at which it should be fitted, the most critical practical stage begins — physically correcting the imbalance. The choice of method depends on the rotor design, the operating conditions and the accuracy required.
Method 1: welding weights on (the most reliable)
This is the most widely used and most reliable method for the majority of industrial rotors (fans, crushers, agricultural machinery).
When to use it:
- On steel and cast-iron rotors.
- When maximum fixing reliability is required.
- Under conditions of high temperatures, shock loads or abrasive wear.
How to weld correctly:
- Surface preparation: carefully clean the weld area down to bare metal.
- Choosing the weight: use steel plates of the appropriate mass.
- Welding: weld all the way round the plate. The weld must be continuous and of good quality.
⚠️ Dangerous: a correction weight that breaks off at 3000 rpm becomes a projectile. Never cut corners on weld quality!
Method 2: removing mass (drilling, milling)
This method is used where fitting additional weights is undesirable or impossible.
When to use it:
- On rotors where protruding parts are not permissible (high-speed rotors).
- On motor armatures, turbine rotors and spindles.
- When very precise correction is required.
Where you can drill:
- Purpose-made bosses on the rotor.
- The faces of discs (away from stress-concentration zones).
- Stiffening ribs (if the design allows).
🚫 It is strictly forbidden to drill:
- Impeller blades.
- Thin-walled parts of the rotor casing.
- Zones near the bearing seats or splined joints.
Method 3: fitting removable weights (bolts, clamps)
This method is convenient for quick correction and where welding is not permissible.
When to use it:
- On rotors that have dedicated threaded holes for balancing bolts.
- On car wheel rims (balancing clip-on weights).
- When frequent re-balancing is needed.
Important points:
- Use high-strength fasteners (grade 8.8 and above).
- Always use washers or thread-locking compound (such as Loctite) to prevent the fastener from working loose under vibration.
Work safety
Working with correction weights demands strict adherence to safety procedures.
- All work to fit and remove weights is carried out only on equipment that is fully stopped and isolated (the LOTO procedure).
- When welding, observe all fire-prevention precautions.
- After fitting a weight, make sure it does not catch on any stationary parts of the casing.
Professional balancing
Our specialists will choose the optimum correction method for your equipment.