High-speed balancing and centrifugal casting plant

The manufacture and repair of rotors is completed with a mass distribution test of the rotor, ensuring the compliance with balancing tolerances.

If necessary, adjustments can be made through the installation of balancing masses.

For that purpose, the system detects mechanical vibrations of rotors at low and high speed ranges.

The achieved balancing quality of the test object is documented in a protocol.

Technical parameters

The system was delivered by Hofmann Mess- und Auswuchttechnik GmbH & Co. KG with the following parameters:

  • Max. rotor weight 32.000 kg
  • Max. weight per bearing pedestal 16.000 kg
  • Min. rotor weight approx. 1.000 kg
  • Long machine bed 8.000 mm
  • Max. rotor diameter above machine bed approx. 2.500 mm
  • Max. hole diameter of bearing head for accepting bearing shells 600 mm
  • Max. bearing spacing approx. 7.100 mm
  • Min. bearing spacing approx. 500 mm
  • Balancing speed range 180 … 4.500 rpm

A separate inspection of the rotor to be tested must be performed for use in this system!

Balancing process
  • Process planning / clarification of all components needed
  • Installing the test object in the balancing and overspeed testing system
  • Testing of all plant components and safety installations
  • Balancing start – ‘pre-balancing’ in low-speed range
  • High-speed acceleration to first critical speed or rated speed
    • Determination of influence coefficients
    • Balancing
  • High-speed acceleration to second critical speed or rated speed
    • Determination of influence coefficients
    • Balancing
  • High-speed acceleration to third critical speed or rated speed
    • Determination of influence coefficients
    • Balancing
  • Heating of winding, including laminated core, if necessary
  • Overspeed test or safety run
  • Balancing for delivery status
  • Electrical testings during operation of test object, such as:
    • Impedance testing, Measurement of ISO value
    • High-voltage testing at rated speed
  • Removal of test object from the balancing and overspeed testing system
  • Preparation of inspection protocol

Dynamic balancing of plain-bearing rotor

The balancing is based on DIN ISO 1940 (Balance quality requirements for
rotors in constant (rigid) state) respectively DIN ISO 11342 (Methods and criteria for the mechanical balancing of flexible rotors). The balance quality is G 2,5 (or by agreement).

The following tests are possible:

Input tests of the rotor (by agreement)
  • Radial runout measurement in rotating machine (measurement points by agreement)
  • Insulation resistance (measurement voltage 1,000 V or by agreement)
  • Measurement of ohmic resistance
Tests in balancing and spin system HS 28
  • Overspeed test or safety run (values by agreement)
  • Performance of overspeed test or safety run for heated test object (by agreement and subject to technical clarifi cation) - ADDITIONAL COSTS -
  • Vibration measurement above the speed after achieving balance quality
  • Analysis of vibration speed at nominal speed
  • Determination of the residual imbalance (according to DIN ISO 11342)
  • Specification of the compensation weights and their position
  • Securing all balance weights
Possible electrical test on slip ring rotors during speed
  • Impedance measurement at nominal speed (measurement current < 10 A)
  • Insulation resistance up to nominal speed (measurement voltage 1,000 V or by agreement)
  • Voltage test at nominal speed (measurement voltage 1,000 V or by agreement)
Preparation of runout measurement in lathe
Output tests of the rotor (by agreement)
  • Radial runout measurement in rotating machine (measurement points by agreement)
  • Insulation resistance (measurement voltage 1,000 V or by agreement)
  • Measurement of ohmic resistance
Parameters of roller bearing machines for roller-mounted balancing system
  • max. rotor mass: approx. 15,000 kg
  • min. rotor mass: approx. 1,000 kg
  • length machine bed: approx. 8,000 mm
  • max. rotor diameter above machine bed: approx. 2,500 mm
  • max. bearing spacing: approx. 7,100 mm
  • min. bearing spacing: approx. 500 mm
  • shaft diameter: 35 mm to 300 mm
Diagram balancing speed range