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Vibration Basics

At its core, vibration analysis is the process of measuring the vibration signals from a machine, analyzing these signals to identify patterns and anomalies, and then interpreting this information to assess the machine’s mechanical health. Every piece of rotating equipment, from massive turbines and industrial pumps to electric motors and gearboxes, generates a unique vibration signature when in optimal condition. Changes to this signature often indicate the early stages of wear and tear or other developing faults.

  • Data Collectors: These sensors convert the mechanical vibrations into electrical signals. These signals are then captured by portable data collectors during routine inspection routes or by permanently installed online monitoring systems that provide continuous data. Wireless sensor technology is also becoming increasingly common, offering flexibility and ease of installation.

Data Processing

The raw vibration signal is a complex mixture of different frequencies and amplitudes. To make sense of this data, it undergoes signal processing.

  • Time Waveform Analysis: This involves looking at the raw vibration signal plotted over time. It can reveal impacting events, modulation, and noise.
  • Frequency Spectrum Analysis (FFT): Most widely used diagnostic tool. Using a mathematical process called Fast Fourier Transform (FFT), the time-domain signal is converted into the frequency domain. This creates a “spectrum” – a graph that shows the amplitude of vibration at different frequencies. Each distinct frequency component in the spectrum can often be linked to a specific mechanical component or fault condition.
  • Overall Vibration Levels: Sometimes, a simple overall measure of vibration energy is trended over time. A significant increase can indicate a developing problem.
  • Trained analysts (or increasingly, AI-powered diagnostic software) examine the vibration spectra and time waveform data.
  • They look for specific frequency patterns, changes in amplitude, and the presence of unusual vibration signatures that are characteristic of known fault conditions.
  • By comparing current readings to baseline data (taken when the machine was known to be in good condition) and established alarm limits, they can identify the type and severity of the potential problem.