A special discounted collection of 9 webinar recordings focusing on a wide variety of vibration, balancing and alignment topics.

Just $45 for EASA members!

Many EASA service centers conduct vibration-based machine condition monitoring programs for their customers. This is a valuable revenue source that aligns the service center as a team member with the customer to provide uptime on their machinery and control maintenance costs. It also puts some of the responsibility for predicting machine failures on service center personnel who may be managing vibration data for hundreds of machines in multiple customer facilities. Given that vibration data is complex, composed of amplitude, frequency and phase, that can be a daunting task.

Muchos centros de servicio llevan a cabo programas de monitoreo por condición basado en la vibración de las máquinas para sus clientes. Esta es una fuente valiosa de ingresos que integra al centro de servicio como miembro del equipo del cliente para garantizar el tiempo de funcionamiento de su maquinaria y controlar los costos de mantenimiento. Esto también pone parte de la responsabilidad de predecir fallos en las máquinas, en el personal del centro de servicio que puede estar gestionando los datos de vibración para cientos de máquinas en múltiples instalaciones del cliente. Dado que los datos de vibración compuestos por amplitud, frecuencia y fase son complejos, esta puede ser una ardua tarea.

Vibration readings provide the best early warning of developing problems in a motor or system component. Other parameters to monitor may include operating temperature of critical components, mechanical tolerances, and overall system performance, including outputs such as flow rate, tonnage, and volume.

High vibration is a common problem for motors that are installed on top of vertical pumps. Its source can be a mechanical issue with the pump, motor or coupling or even hydraulic forces from the pump.

Vibration is the most effective and well-recognized parameter for assessing the mechanical condition of electric motors. Generally, lower vibration levels are equated with improved reliability. However, arbitrarily reducing the vibration level specification for acceptance of new and repaired motors will not necessarily result in improved reliability, and it will definitely increase costs. Further, reliance on vibration levels at 2x line frequency (2xlf) as an indicator of electric motor reliability is not effective.

There are three fundamental parameters for machinery vibration data: amplitude, frequency and phase. When testing machine vibration, amplitude and frequency are the two primary measurements for acceptance testing and for diagnostics. Both of these parameters have several units in which they can be recorded. Converting from one unit of measurement to another is not difficult if both amplitude and frequency data are available. In many cases, only amplitude measurements are available, without the needed frequency information, so conversion to other amplitude units is not possible. Knowing when conversion is possible and how to a apply conversion formulas is important when assessing customer specifications and analyzing diagnostic data.

When machine vibration increases, one of the first questions asked is: "Is a failing bearing causing the vibration?" In the case of rolling element bearings, it is not difficult to separate vibration caused by a failing bearing from other common faults such as unbalance, misalignment, looseness, etc. But sorting out vibration from a failing rolling element bearing (here-after called "bearing vibration") from process sources such as flow induced and background vibration can be more demanding. The secret is to identify the frequency at which a flaw on a roller or raceway will impact the mating bearing component. These are commonly known as bearing fault frequencies.

Topics covered include:

• Simple to complex steps in identifying bearing vibration
• "Locate rpm" function
• Occurance of sidebands

Resonance is a property of all mechanical structures. It can be described as a sensitivity to a certain vibration frequency. For machinery such as electric motors, pumps, turbines, etc., it becomes a problem when small vibratory forces from the machine operation are amplified by mechanical resonance. The result can be very severe vibration levels, even when the exciting forces are small.

When a motor is test run in the service center, the two most common vibration frequencies that occur are at 1x rotating speed (1x rpm) and at 2x line frequency (2x lf). High 1x rpm is often corrected by balancing, and the 2x lf is traditionally attributed to air-gap anomolies or voltage or winding unbalance. However, there are those cases where the traditional approaches are unsuccessful and technicians and managers are left scratching their heads. In these difficult cases, there is often a combination of electrical and mechanical vibration.