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By: Vibtech Analysis  09-12-2011
Keywords: Vibration Analysis, Infrared Thermography, Rotating Equipment

Vibration Analysis Overview

Vibration Analysis is the science and art of measuring the vibration levels in rotating equipment such as motors, pumps, fans, compressors, gearboxes, cooling towers, production equipment etc. The vibrations are recorded while the machine is under normal operating conditions. The Vibration Analyst then interprets the raw data and identifies any mechanical problems that may exist as well as the cause of the problem.

The key to Vibration Analysis is knowing the operating speeds of the various components of the machine being measured. When the vibration readings are recorded, they are broken down into a graphic format called a spectrum. Basically, this is a graph where the ''X'' axis is the frequency at which the vibrations are occurring and the ''Y'' axis is the amplitude (or severity) of the vibration. Once the Analyst knows the speeds of the various components of the machine and has determined the frequencies of the recorded vibrations, he can then determine the source of the vibration. Consider a Center Hung Fan where the following information is known:Motor RPM: 1780   Fan RPM: 1200   Belt RPM: 500In this example, a customer may be complaining his motor is vibrating excessively and request the machine be checked out. If the Analyst (after taking measurements on the whole machine) sees that the predominant frequency of vibration on the motor is at 1200 CPM, he can comfortably say the source of the vibration is the fan since it is the only component rotating at that speed. Then, focusing on the fan, the Analyst would determine the reason such as unbalance, misalignment, bent shaft, etc., as well as the appropriate course of corrective action.Consider that a single vibration analysis is like a ''snapshot picture'' of the machine. It shows the mechanical condition of the machine at the moment the readings were taken. If bearings were showing a medium amount of wear, comments would be made to that effect. However, what would not be known is how long it took the bearing to deteriorate to that condition. If it was a gradual deterioration over a year, there would be little immediate concern. Conversely, if the bearing had only been installed two weeks earlier, immediate corrective action may be required. Predictive Maintenance Programs involve the trending of vibration over time.

Infrared Thermography Overview

Infrared Thermography is the ideal tool to determine not only how hot an object is, but more importantly, how it differs from it's surrounding components. This technology is most often used to identify failing electrical components. It is a characteristic of electrical components that as they start to fail, individual parts become hotter than normal. Providing they have a direct line of site to the problem area, infrared cameras can easily identify these "hot spots" by providing visual images.  This technology is now commonly used to identify many other types of problems where temperature differential would indicate a problem. Roofing anomalies and oven insulation breakdown would be prime examples.

Keywords: Infrared Thermography, Predictive Maintenance Programs, Rotating Equipment, Vibration Analysis,