Rotor Balancing and Why It Is Essential

Rotors are components that are found in various assemblies and machinery, used to transform electric or electromagnetic energy into rotational motion. In order for such equipment pieces to perform optimally, they must maintain an even balance and distribution of weight across their rotational axis. The unbalancing of weight on a single side can happen to rotating parts of any assembly, and uneven mass distribution will result in the misalignment of a component’s rotation center in regard to the geometric axis. This can deter proper efficiency and safety, and as thus proper balancing should always be maintained. With rotor balancing, noise, vibration, and other various issues can be deterred for the health of a system.

When discussing rotor equipment in general, such components can be classified by whether they are rigid or flexible. Knowing this is crucial as it will affect the general balancing of a system. Rigid rotors are capable of being balanced at lower speeds, relying on centrifugal force for determining if there is an uneven distribution of mass. Meanwhile, flexible rotors are deflected outward from the assembly’s rotational axis, and increases in operational speed will cause the center of rotation to become more distant from the rotational axis. While a rigid rotor may be balanced while operating at slow speeds, flexible rotors should only be balanced in stages where adjustments are made during low speed operations with slow increases.
During unbalanced conditions in both flexible and rigid rotor assemblies, a number of detrimental effects can occur, ranging from minor inefficiencies to outright damage. With vibration, more energy may be expended by a system, and the forces and loads resulting from such issues will cause a more rapid increase of wear to rotor parts. As other components such as bearings and mountings may be affected as well, unbalance can quickly cause hazards.
If vibration becomes excessive, noise will greatly increase as the structural integrity of the assembly degrades. The structural housing, bearings, and mounting components are often the hardest hit with stress, and premature wear can occur to such components. Once structural integrity is lost due to the loosening of fasteners, stability will drop. This can even begin to spread to various piping, cabling, and electrical connections, eventually presenting hazards to surrounding individuals and systems.
Before one can address unbalance, it is crucial to understand that there are three forms of unbalance that may occur. Static unbalance is caused when the mass axis is displaced parallel to the shaft axis, and this type of unbalance is often combated in a single axial plane. Couple unbalance, meanwhile, is when the mass axis intersects the running axis. To remedy this issue, corrections are made in two axial planes. The last form of unbalance is dynamic unbalance, that of which results from a combination of static and couple unbalance issues as a result of the mass axis not intersecting with the rotational axis. Similar to couple unbalance issues, dynamic unbalance may be remedied by correcting balance across two axial planes.
When initiating rotor balancing procedures with a rotor balancing kit, one should first begin with vibration and phase measurements. Once a vibration analysis is finalized, radial and axial vibration readings are taken. Then, the assembly should be fully cleaned and all loose items should be removed. With the use of trial weights, trial runs can be conducted while adding correction runs. Then, the trim run can be conducted with trim weight corrections as necessary. For single plane procedures, no more than two trim runs should have to be made for a correction. In such cases, the procedure should be repeated. This is the same for many two-plane procedures as well as two trim runs should be suitable for a balance job.
In the case that procedures are carried out and the rotor is still unbalanced, there are some issues that may be occurring. These include thermal sensitivity, rotor erosion, material buildup, interfering resonances, speed changes, or loose rotor parts. When you are in need of a rotor balancing fan assembly, rotor balancing assembly components, rotor balancing parts, or other various items for your rotor assembly, there is no better alternative to ASAP AOG.
ASAP AOG is a premier supplier of parts, presenting customers an unrivaled inventory containing over 2 billion new, used, obsolete, and hard-to-find items that have been sourced from thousands of top global manufacturers that we trust. Take the time to explore our offerings as you see fit, or take advantage of our provided search engine and filters to quickly narrow down results with ease. Once you have established which items you wish to procure, you may request a quote for your comparisons through the submission of an RFQ form as provided on our website. Give us a call or email today, and we would be more than happy to assist you through the part procurement process however we can.


Recent Twitter Posts