Both Preventive and Predicative maintenance models show a keen interested in mechanical vibrations and the effect they have on planning and maintenance. For the rest of this article vibration analysis looks at any vibrating element of a piece of machinery and how changes in frequency, strength or duration of vibrations can be signals of maintenance that needs to be addressed.
As a general rule the more a piece of plant vibrates the more prone it is to encountering problems. Increased vibrations can be caused by a tension increase, wear of materials, or a damaged component. If left unattended the increased vibrations can cause energy loss, increased noise within the plant and in worst-case scenarios the eventual damage of a piece of equipment.
- Frequency: The time required to complete one cycle of a vibration. In studies of vibration the terms used CPM (cycles per second) or Hz (hertz).
- Displacement: The total distance that the vibrant element moves. From one end to the other end of its movement.
- Acceleration: With the frequency is increasing or decreasing.
- Direction: The vibrations may occur in 3 linear directions and 3 rotational directions.
Types of vibrations:
- Free vibration: vibration caused by a system due to an instantaneous excitation.
- Forced vibration: vibration caused by a constant excitation of mechanical movement.
Most Common Reasons Why A Machine Has Began To Vibrate:
- Vibration due to being unbalanced (rotating machinery).
- Vibration due to a misalignment (rotating machinery)
- Vibration due to eccentricity (rotating machinery).
- Vibration due to the failure of bearings
- Vibration caused by problems of gears and belts (play, lack of lubrication, friction, etc.).