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Balancing of high-speed electric rotors

Advantages of PMB balancing for high-speed electric rotors

A high-speed electric rotor places special demands on the balance quality due to its high speed. As motor shaft in electric turbochargers, compressors, hydrogen pumps and also in modern vacuum cleaners, these components sometimes rotate at well over 100,000 rpm. The unbalance effect is disproportionately high compared to standard electric rotors, since the effect of the unbalance increases quadratically with the speed.

Tighter manufacturing tolerances are no longer possible or are very expensive and only provide a limited solution. In high-speed motors, eccentricities of as little as 1 µm can have a functionally detrimental effect. The particularly good balancing of HighSpeed rotors is the only technically feasible and at the same time the best solution.

PMB is your experienced partner from consulting via balancing of prototypes/small series in our contract balancing department up to the equipment of your series production with our systems. Read more about the values achieved and how they were achieved below.


PMB Balancing machines for high-speed electric rotors

For measuring the unbalance, high-speed electric rotors are also supported either at the shaft stubs on bearing blocks with rollers or friction bearings - the results below were obtained on rollers. In order to compensate for the effects of unbalance caused by pressing on a bearing, we would be pleased to measure your rotors with mounted bearings, if this is possible in your assembly process. The results below were achieved without pressed-on bearings.

Our round belt drive has proven itself as a reliable actuator. Simple, universal and very good balancing results at the same time.

As a typical example here are some specifications of the rotor of an electric compressor with D=18 mm and L=135 mm, which has been balanced on our Balancer Universal 500 on roller blocks:

Initial unbalance max. per plane

800 mgmm = 89 mg Unbalance mass

Allowed residual unbalance per plane

50 mgmm = 5,6 mg unbalance mass

Achieved residual unbalance per plane

5 mgmm = 0,56 mg unbalance mass

Standard deviation from 50 measurements on roller bearing blocks

1,58 mgmm = 0,176 mg

This is excellent for R&D and prototype construction, as the unbalance can be excluded as an influence in further product development. And for production it is very reassuring, as there is enough margin. Instead of the usual 10x better than required, we were immediately more than 30x better.  On a balancing system that can be quickly modified to other sizes of highspeed electric rotors.

With the OnDesk 500 and Universal 500 balancing systems, the majority of the sizes and shapes of the high-speed electric rotors can be handled with excellent results. For particularly small rotors there are variants of the balancing stands, just talk to us about them.

  • CAROBA®Balancer OnDesk 500: Compact and flexible universal balancing system for the worktop, manual and semi-automatic balancing
  • CAROBA®Balancer Universal 500: Universal balancing machine, manual and semi-automatic balancing
  • To ensure that the system is precisely matched to your process requirements, we would be pleased to discuss fully automated balancing machines for high-speed rotor balancing with you. Our laser balancing machines are of particular interest here.

If the investment in PMB balancing machines does not yet pay off for you: You can also use the advantages of our technology by using the balancing service of our contract balancing.

Unbalance correction

Unbalance correction is carried out manually for moderate quantities. Since attached weights have a tendency to flying off at high operating speeds, users of our balancing systems for high-speed rotors usually use subtractive processes (grinding, drilling, milling).

With our fully automated laser balancing systems we gladly recommend the correction of unbalance by laser ablation. Highly accurate, chip-free, force-free, quick - correction at equal level with our highly accurate unbalance measuring technology.

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Balancing technology according to application

If you have your own products that you would like to balance or questions about balancing technology, please send us an e-mail or use our contact form. We will get in touch with you as soon as possible.

E-mail : or Phone +49 631 204015 0

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