How is rotor imbalance measured?
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How is rotor imbalance measured?
The only way to assess the unbalance state is to add balance correction weights at various locations and using some calculation tool such as the influence coefficient method, and if the vibration is greatly reduced at most (or all) speeds, then a reasonable estimate of residual unbalance can be calculated based on …
What is GMM in balancing?
The units of unbalance are mass times radius, for example: a weight added to a certain position on the part being balanced would shift the mass axis into the running axis and therefore be in balance. For metric measurement the units will be gram-millimetres (gmm) or for large rotors, gram-centimetres.
What are the balancing of rotor?
Balancing is the process of attempting to improve the mass distribution of a rotor, so that it rotates in its bearings without uncompensated centrifugal forces. This is usually done by adding compensating masses to the rotor at prescribed locations.
What are the types of balancing?
There are three different types of balance: symmetrical, asymmetrical and radial. The human figure in this diagram is symmetrically balanced; the same on the left and right sides of a central axis.
How do you do rotor balancing?
Typical Single-Plane Procedure
- Set up equipment on the rotor as outlined by the balance equipment manufacturer.
- Make “reference run” or “calibration run,” measuring vibration and phase.
- Add trial weight.
- Make trial run.
- Remove trial weight.
- Add correction weight.
- Make trim run.
- Add trim weight if needed.
Why do you need a rotor balancing machine?
Balancing machines are designed to precision balance rotating assemblies so there will be minimal vibration when assembled and running at rated speed. The trick is, a rotor is balanced while unassembled and rotating at much slower than rated speed, so the method and technology used is very important.
What are the balancing standards for rigid rotors?
6 BALANCING STANDARDS. For rigid rotors, G , is the product of specific unbalance , e, and rotor maximum service angular velocity. Service angular velocity is nothing but the service RPM expressed in radians per second. ( w )
How is the residual unbalance of a rotor defined?
ISO 1940 defines the balance quality of rotors for a variety of services by defining a host of balance quality grades for different types of rotors. The residual unbalance for a rotor is defined in this standard using velocity magnitudes starting at 0.4 mm/sec and increasing in factors of 2.5 (0.4, 1.0, 2.5, 6.3, etc.).
How much Tir do you need to balance a rotor?
Consistently maintaining less than 0.15 mils TIR for mounted components on most shafts for industrial machinery will be impractical, making the mounting process a likely larger contributor to the resulting unbalance of the mounted component than the balance condition of the part itself.