Introduction into Machine Diagnostic Technologies(cont.)

Vibration analysis is a diagnostic technique to determine the condition of a machine based on the dynamic forces. Many techniques to determine machinery condition, but vibration analysis remains the most cost effective approaches. The principle of this technique is that machines produce vibrations caused by the mechanical actions. When the actions change, vibration amplitudes change. spectral analysis is used to determine the cause. Many mechanical and even some electrical problems can be detected before they cause a failure. Often before performance is affected. This creates an opportunity to make repairs or adjustments to your schedule. Also by identifying and correcting problem components, most failures can be eliminated.

In general vibration occurs when an object with mass is in motion. Most machines have several characteristic motions which lend them to the world of vibration rather well. The primary characteristics are rotational speed of the motor, the belt or chain speed, and the rotational speed of the driven unit. Other motions include gear meshing, ball/roller bearing motions, blade/vane rotation, and electrical noise. Also there is a category of machine specific phenomena that include cavitation on pump impellers, resonant frequencies, oil whirl and many more.

A vibration survey is done periodically after a database has been established, depending on facility needs. The more often a survey is done the less likely a breakdown will surprise the maintenance staff.

A data collection device is used to digitally sample the electrical signal from the vibration sensor. The data is processed and usually digitally stored for unloading into a computer after the collection process is completed.

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Last updated: November 24, 2002