Each rotating body has got an unbalance. Because in practice its mass axis (containing the center of gravity) never coincides with the rotational axis. There are many reasons for the size of that unbalance, for example the procedures used for machining or assembly. When a rotating body is revolving in its bearings the unbalances cause dynamic forces and noise. Hazards for persons, machines and the environment may occur. Therefore balancing is a must for modern machines running at high speeds and requiring high precision.

For balancing it is checked whether the mass axis of a rotor is displaced from its rotational axis and how distant that is. If necessary – the mass distribution of a rotating body is being changed by balancing. As a result the forces and vibrations caused by the unbalance stay within permissible limits.

In general a rotor shows a dynamic unbalance. That dynamic unbalance will be balanced in two arbitrary axial planes of the rotor. For some rotors like grinding wheels or fan impellers balancing in just one axial rotor plane is sufficient. When balancing the necessary changes in the mass distribution of a rotor for the given balancing planes are being achieved by adding or removing mass or by repositioning masses.

Balancing tolerances, methods for balancing and limits for machine vibrations are subject to technical rules and standards (for example ISO 1940-1; ISO 10816-3).

Balancing is being performed either on stationary horizontal or vertical balancing machines or at site using portable balancing equipment.

The HOFMANN horizontal and vertical universal balancing machines provide optimum operator support when balancing different kinds of rotors. This is valid for manual or manually controlled mass correction.

• Balancing of rotors with cylindrical shape on horizontal universal balancing machines
  - by placing their journals into adjustable roller bearings or
  - by mounting complete aggregates into special tooling.
• Balancing of disc-shaped rotors on vertical universal balancing machines using suitable clamping adaptors.
• Drive systems to efficiently and precisely achieve the required balancing speed.
• Unbalance measuring system
  - for easy setup of the balancing job,
  - high measuring accuracy and
  - clear display of the measuring results about the necessary mass correction.
• Options to best fit the Hofmann solution to the given balancing job.