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Frequency, Amplitude, Period, RMS, Spectrum, Frequency domain view, Time domain view, Time waveform, Displacement, Velocity, Acceleration in this video we will explain the main terms for vibration analysis measurement and how to create a factory measurement journey known as a route for your predictive maintenance in condition monitoring program.
Frequency is (in vibration measurement) the number of occurrences of a repeating event per second, and the unit is Hz.
Period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency.
Amplitude is the maximum extent of the repeating event.
The RMS value for sinusoidal functions is 1⁄√ 2(it equals approximately 0.7) of the 0Peak amplitude.
Amplitude can be measured or displayed in 3 types of Physical quantities: Displacement, Velocity and Acceleration.
Displacement means the distance between the stable and exceed position. Units are mm, micrometer or thousandths of an inch, or mils if you prefer.
Velocity is the rate of a change of a distance (displacement) with respect to time. Units are mm/s, or ips. Acceleration is the rate of a change of a velocity with respect to time. Units are g or m/s2.
We have 2 main ways of displaying the vibration signal ( for us this means Frequency and Amplitude).
The first one is the Time waveform or Time domain view.
The second type is the Spectrum or Frequency domain. It is the view of each frequency component of the sensor´s total movement. It allows us to see all amplitudes of frequencies the time waveform is made of separately. According to Fourier analysis, any physical signal can be decomposed into a number of discrete frequencies, or a spectrum of frequencies over a continuous range. You can imagine a spectrum as an equalizer which is visualizing the amplitudes of the frequencies the music is made of.
How to create a factory measurement journey The Route.
For the beginning of our Predictive maintenance program we will use 2 measurement types per measurement point velocity in mm/s and acceleration in g. The measurement point is the place on the machine where we will be taking the measurement. There will be more measurement points on each machine. For example, on each bearing housing of the machinery component plus one on the axial direction on the machinery set. We will create our route tree in the DDS software and it will basically guide us to which department we should go, to which machine and where to place the sensor to take our measurements.
Track the trend of vibration.
Now you have created your Route tree and you regularly measure your machines (e.g. 2 times per month). It is time to track the trend of vibrations on individual measuring points and see their development in time. Is your trend of velocity and acceleration measurement stable? A stable trend with acceptable values means that your machine (or bearing) is running under stable conditions, then you should not be worried and this machine can be operated without any restrictions.
Attention: Even if the trend is stable, there can be cases when the machine will break down without any warning. This can happen for example if the machine runs with some manufacturing defect. It does not happen very often, but it happens. Is your trend of velocity or acceleration measurement rising? Is it the Velocity measurement? Then as we learned it will be a mechanical fault related to the speed of the machine such as unbalance, misalignment or looseness. You should measure the machine more frequently and look for a deeper analysis of the machine to find out what the problem is. Is it the Acceleration measurement? This higher frequency measurement is most often related to bearings. Grease the bearing. Measure it more frequently and if the value is still rising you should plan to change the bearing.
Predictive maintenance, and particularly vibration measurement, is one of the best and most proven methods for knowing the actual condition of your machinery. It allows you to track its condition over time and enables you to plan / schedule potential repairs of the machine. However, it can never work 100% and some sudden machinery break downs can still occur.
To keep your machinery running, try to do more than just regularly measure your vibrations.
• Be smart, try to get to know your machine
• Keep your machinery clean
• Observe the machine, look for potential oil leaks, air leaks etc.
• Look for potential foundation cracks, structure cracks, loose bolts
• Listen the machine. Especially look for sudden noise change.
• Share information about the machine. Use the „Buddy System“. In other words, if you discover some unusual behavior in any machine, tell your work mates. You can not only avoid an unexpected break down, but you can also save your colleague's life!

00:00 02:50 Vibration signal
02:50 05.30 Frequency domain (spectrum) / Time domain
05:30 11:04 Factory measurement ROUTE