Balancing Solutions for Turbomachines

Turbomachines are high-quality machines used in areas like power plants or the process industry. Rotors from turbomachines place special demands on balancing technology.

Steam turbines, gas turbines, turbo generators and turbo compressors are machines whose rotors usually run beyond at least one critical speed. Therefore, they are balanced as flexible rotors. The HS type high-speed balancing and spin testing installations meet all requirements for balancing and spinning flexible rotors with multiple correction planes and multiple speeds. Flexible concepts – for example for propulsion and safety structures – enable Hofmann to optimally adapt the high-speed balancing and spin testing installations to specific project requirements, or to provide them as turn-key solutions.

In addition to balancing, rotors from turbomachines undergo further special tests.

For example, the field winding of a turbo generator is supplied with electric current in order to evaluate the influence of rotor heating on the balancing result. Magnetic field and electric impedance measurements are performed on the rotating rotor to determine the electrical properties and detect winding defects.

With many rotors from turbomachines, the runout testing must meet specific requirements. Hofmann’s type UHR runout testing machines measure all important runout values (total, mechanical, electrical) with the rotor set in V-blocks. To check on-site runout, the RO 7000 portable runout testing system is used.

Installations for Low- and High-Speed Balancing and Spin Testing

Type HS 16 - 34

The high-speed balancing and over-speed testing installations are used to balance flexible rotors under operational conditions and to perform spin tests at over-speed. Hofmann HS installations cover rotor weights from just a few kilograms up to 100 tons.

Special features

  • Isotropic bearing pedestals 
    • with high stiffness to provide close to in-situ bearing conditions
    • with high measuring sensitivity due to Hofmann force measuring principle even at low speeds
    • designed for use with modern tilting pad journal bearings (large outer bearing diameter, higher oil flow, higher speeds)
  • Roller bearings for low-speed balancing
  • Flexible containment concepts
  • Approval of containment capability by state-of-the-art computational ballistic perforation analysis applying actual fragment data

Application

  • Balancing of flexible rotors from turbo-machinery
    • under atmospheric or vacuum conditions
    • at low and high speeds
    • in their own bearings
  • Spin-testing of the rotors at over-speed
  • Special tests with rotors from electric machines
  • Runout measurement

Additional product information

Horizontal Runout-Testing Machines

Type UHR

Hofmann’s type UHR Runout-Testing machines measure the mechanical, radial and axial runout of rotors in multiple axial planes. Runout is measured with both a tactile sensor (mechanical runout) and an eddy sensor (total runout). The difference between the total and mechanical runout yields the “electrical runout” (the systematic measurement error of the eddy current sensor). The results of the runout measurements are used to compare given values with target values and to perform corrections, when necessary.

A rotor is placed on V-blocks for runout measurement and is driven jolt-free using an end-drive.

Special features

  • High precision, independent measuring machine
  • No blocking of other machine tools when measuring runout
  • Prevention of measuring errors for example due to chucks used in lathes
  • Optimum accessibility to the measuring planes
  • Measuring system based on Windows software for intuitive operation
  • Measuring protocol for quality assurance
  • Precise and distinct result representation for an efficient runout correction

Application

  • Measurement of shaft surface profile / runout with high resolution
  • Measurement of
    • electrical runout
    • mechanical runout
    • total runout
    with precise angular reference
  • Checking of the runout of measuring planes used for monitoring shaft vibrations acc. to ISO 20816-1, API 610, API 612, API 617 or API 687
  • Testing of rotors in manufacturing
  • Evaluation of rotors prior to a repair

Additional product information

Portable Runout Testing System

Type RO 7000

Hofmann’s Runout Testing System RO 7000 provides a solution to measure the mechanical, radial and axial runout of rotors in multiple axial planes. Runout is measured with both a tactile sensor (mechanical runout) and an eddy current sensor (total runout).

The difference between the total and mechanical runout yields the “electrical runout” (the systematic measurement error of the eddy current sensor). The results of the runout measurements are used to compare given values with target values and to perform corrections, when necessary.

Special features

  • Measuring of mechanical as well as electrical runout
  • Portable system for universal application
  • Flexible und simple handling
  • Compatible to Hofmann’s stationary Runout-Testing-Machines UHR
  • Measuring protocol for quality assurance
  • Precise and distinct result representation for an efficient runout correction

Application

  • Measurement of radial and axial runout of rotors in
    • manufacturing
    • repair
  • Measurement of
    • electrical runout
    • mechanical runout
    • total runout
    with precise angular reference
  • Checking of the runout of measuring planes used for monitoring shaft vibrations acc. to ISO 20816-1, API 610, API 612, API 617 oder API 687