Before we begin differentiating between static and dynamic bench balancing, we must first understand the concept of imbalance and the consequences of having an unbalanced rotor.
Consequences of rotor imbalance
Imbalance is one of the most common sources of mechanical vibrations. In rotors, imbalance is inevitable, and it needs to be corrected. Imbalance results in variable forces on the system that generate vibrations that are detrimental to us. Balancing is essential because an imbalance can reduce the lifespan of suspensions, bearings, casings, foundations, and other components. Additionally, it is common for screws to become loose and for electrical connections to generate false contacts. The efficiency of the machinery will also be affected, and there is a possibility that it may impact the workers themselves through vibrations or noise, for example.
Rotor balancing process
When we talk about rotor balancing, we refer to the process of compensating for mass distribution and reducing imbalance. This can be achieved by adding or removing mass, although adding mass is more common.
Another aspect to consider when discussing the differences between static and dynamic balancing is the type of systems. Systems can be rigid or flexible. Rotors are classified based on the relationship between rotational speed and natural frequency. When the rotational speed is higher/lower by 30% compared to the natural frequency, we have a rigid system. Otherwise, it is a flexible system. A flexible rotor tends to have more imbalance due to the deformation caused by continuous machinery usage. This is why it is important to balance the rotors of industrial machines at their nominal rotational speed.
Just as we can differentiate between static and dynamic bench balancing, imbalance in rigid rotors can also present both options. Static imbalance can occur in balanced or statically unbalanced rotors. In the first case, the center of gravity remains fixed relative to the bench, regardless of the rotor's position. In the opposite case, there is a unique stable equilibrium position with the center of gravity downward, which can be detected when the rotor is stopped.
Dynamic and static balancing
In summary, we can state that every rotating equipment tends to have an imbalance. This poses a serious problem for the equipment when the imbalance reaches a certain intensity, as it can cause damage. In our workshops, we can perform dynamic and static balancing to prevent serious issues with the rotor. You can see a real example of balancing on our website. Dynamic balancing involves nullifying the inertia forces and moments of inertia forces. Static balance can be achieved without dynamic balance. Additionally, we cannot detect this situation if the rotor is stationary. The detection process is done by measuring vibrations at support points in the radial direction at the rotational frequency with a 180º phase shift between the supports. Regarding static balancing, the center of gravity remains fixed relative to the bench for any rotor position.
Would you prefer us to perform on-site balancing? This allows us to correct and differentiate the different levels of vibration in unbalanced rotors without the need to dismantle the equipment. The process is carried out using an advanced vibration analyzer that accesses the rotor through the recording window. Finally, the balance condition is checked according to ISO-1940 standard. This type of balancing usually takes between 2 and 4 hours of work, conducting tests at the machine, with several motor starts. It is very important to periodically supervise the rotor to ensure optimal performance.
At Equilibrados CHÍA, we hold UNE certification in ISO 9001/2008 and ISO 6103:2014 to guarantee maximum quality and safety in personalized and effective industrial machinery maintenance and balancing processes.
If you have any questions about the balancing process of your industrial machinery, issues with vibrations in rotating elements, or if you would like to request a quote, please don't hesitate to contact our team.