Vibration measurement

In order to assess the condition and performance of machines and systems, various parameters are measured, including

• Amplitude of the vibrations: This refers to the strength or intensity of the vibration. High amplitudes usually mean wear and tear in the machine.
• Frequency: This measures how often a vibration occurs within a certain period of time. Each machine has its own "normal" operating frequency, and deviations from this can indicate problems.
• Phase: This indicates at what point in the vibration cycle the vibration is occurring. Phase is often measured in degrees or radians and is important to understand the temporal relationship between different vibrations.
• Direction of vibration: The direction of vibration can provide information, for example, about an imbalance or misalignment in rotating machinery.
• Time history pattern: Analysing the time history of the vibrations helps to identify intermittent changes in the operating condition of the machine.
• Temperature: The temperature is often also monitored, as an increased temperature can be an indicator of increased friction that leads to vibrations.

Where exactly the measurement is taken depends on the purpose of the measurement and the type of component. In the case of motors or pumps, vibrations are often measured at bearings or housings in order to assess the condition of the machine. This can be done with one or more vibration sensors.

The measuring devices record the amplitude, frequency and phase shift of the vibrations. The position of the sensor is crucial here, as it strongly influences the accuracy and relevance of the measurement data.

The correct interpretation of measurement data from vibration measurements is crucial. It determines whether or not preventive measures should be taken.

The following steps must be observed:

• Selection of measuring points: Firstly, ensure that the measuring points on the machine have been selected correctly.
• Collecting baseline data: Means collecting data when the machine is in a normal operating condition. This data serves as a reference for future measurements and helps to recognise deviations.
• Trend analysis: Regular monitoring of vibration data is crucial. By tracking changes over time, deviations can be recognised at an early stage.
• Diagnosis and measures: In the event of deviations, further investigations should be carried out to determine the exact cause of the vibrations.
• Documentation: All vibration measurements and analyses should be carefully documented. This helps to track trends and enables effective maintenance planning.

Analysing vibration data can be very complex and require specialist knowledge and experience. It is therefore often advisable to consult an expert in vibration analysis. This ensures that the data is interpreted correctly and appropriate measures are taken.

The frequency of vibration measurements varies. It depends, for example, on the type of system, the operating status, the previous maintenance history, the manufacturer's specifications or legal standards.  

The rule of thumb: preventive maintenance measures such as vibration measurements help to prevent breakdowns and extend the service life of systems. A regular review and adjustment of the maintenance schedule based on the latest operating data and experience is therefore recommended in any case.