In-Situ Balancing

• Eliminates the requirements to completely dismantle and reassemble plant equipment to enable balancing of machine components
• Improves productivity
• Reduces downtime, labour and material costs
• Can be planned into scheduled short time outages e.g. machine mould or process changes
• Extends bearing and machine life
• Reduces the possibility of catastrophic failures
• Increases safety

There are two main types of in situ balancing:

1. Dynamic balancing: performed by measuring the forces and moments that are generated by the rotating machinery.
2. Static balancing: performed by measuring the mass distribution of the rotating machinery.

There are two main methods of in situ balancing:

1. Trial and error: involves adding or removing weight from the rotating machinery until the desired balance is achieved
2. Computer-aided method: uses a computer to calculate the amount of weight that needs to be added or removed from the rotating machinery.

It is common practice to remove a rotating element from a machine for machine balancing. Occasionally this may yield poor, or even worse than original, unbalance vibration. This does not necessarily mean the rotor has been incorrectly balanced; it may simply be caused by the differences between test stand and operating conditions.

A shop balancing machine will have different bearings, stiffness and structural response, therefore machine balancing cannot duplicate the actual machine “system” and it’s response. For these reasons, including time, cost and convenience, the in-situ balance method is often the preferred option.