Balancing Rotary Equipment

Balancing your rotary equipment

For over 80 years Elma Services has been a specialist in balancing rotary machine parts for all types of industry. Vibrations cause structural components to detach within a rotary tool. This often leads to damaged machinery and/or machine foundations. Also conduits and electrical cables are prone to break.

Imbalance significantly reduces the operational safety of your machine. This is why balancing contributes both to a longer machine life and a higher personal safety of the operator. Elma Services has all the specialized knowledge, balancing equipment and service engineers to re-balance small, large, light and very heavy machine parts. We are able to do this in-situ or in our own fully equipped workshop.

Types of Imbalances

There can be three types of ‘imbalance’ in a rotary machine:

The “falling” of e.g. a fan in stand-still position indicates a static imbalance. The central principal axis is displaced parallel to the rotating centerline. Static unbalance can be corrected by adding or removing weight in only one correction plane. Read more on static imbalance.

Couple unbalance happens when two unbalances exist 180 degrees apart, but in different planes.  This condition of unbalance has a central principal mass axis intersecting the rotating centerline. Unlike static unbalance, couple unbalance cannot be detected by allowing the rotor to spin freely.  In fact, during the process of static balancing, one can add the weight in the wrong plane. When the weight is added disproportionately, a coupled unbalance is created.  Couple unbalance can only be detected when the part is rotating and can be identified by comparing the bearing or shaft vibration amplitude and phase readings at each end of the rotor. Read more.

The vast majority of imbalances are formed by dynamic imbalance. Dynamic imbalance is the combination of static and couple imbalance. On simple machines, there is usually more static imbalance than couple imbalance. On more complex machinery, with more than one coupling or several spots on the rotor where imbalance can occur, couple imbalance is usually the bigger factor.

When the service engineers of Elma balance a machine, they always balance out the static imbalance first. Once that has been solved they take care of the coupling imbalance. When balancing for coupling imbalance, they always need to balance in multiple planes.

For a number of drive applications – e.g. pumps and hammer mills – the motor’s axle needs to be in perfect line with the axles of the driven rotor. Misalignment results in vibration and unnecessary wear, just as is the case with an imbalanced machine. Elma Services performs vibration analyses on site. In order to identify and repair the described deviations Elma uses advanced laser alignment equipment

Balancing on site

Elma Services also preforms balancing assignments on site. In this case it is important that:

  • The equipment requiring balancing is accessible, for example by an inspection hatch.
  • The equipment can be started and stopped a number of times.

The measuring equipment combines measuring along with the calculations required to determine the relationship between the measured values and the imbalance to be eliminated. These activities are performed globally.

More information?
photo Mike Klasens
Mike Klasens
Inside sales engineer
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photo Teus van der Grift
Teus van der Grift
Workshop Coordinator Balancing
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