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    ISO 9001:2008

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Vibration analyzer (VA-12)


Portable vibration analyzer for Equipment
Diagnosis and On-site Measurements

Vibration Meter VA-12 With FFT analysis function


Vibration Meter Mode

Vibration Meter Mode Applications

Simple Diagnosis

Vibration magnitude
Measuring the magnitude of vibrations is a useful diagnostic technique for ascertaining that machinery is operating normally and checking for signs of possible problems.
For example, when vibrations exceeding the reference value in the velocity range (up to 1000 Hz) are detected, the presence of an imbalance, misalignment, or loosening condition can be suspected, whereas vibrations in the acceleration range (1 kHz to about 12 to 15 kHz) point to possible bearing or gear problems.
Crest factor
The crest factor (C.F.) is an indication of the impact characteristics of a waveform. It is determined by the ratio between the RMS and peak values.
Higher crest factor values indicate a stronger impact quality.
The crest factor of acceleration measurements is useful for detecting the early stages of bearing damage.
Crest factor = Peak value/RMS value

The vibration waveform of a bearing with a fault in the initial stage is shown in the example below.
Compared to the waveform of a normal bearing, the crest factor is higher.


Maintenance Management of Machine Equipment

By periodically measuring the vibration magnitude and comparing the results to a reference value, the equipment condition (normal or potential problem) can be diagnosed.

Using an absolute evaluation standard
ISO 10816 series (Evaluation of machine vibration by
measurements on non-rotating parts).

According to ISO 10816-1:1995 / Amd. 1:2009, evaluation criteria for mechanical vibration over a specified range are to be decided by agreement between the supplier and the user of the machine, and boundary values for evaluation are to be determined in consideration of the measurement position and the support rigidity of the machine etc.
Reference value

A: Newly installed machinery will normally be within this range.
B: Long-term continuous operation allowed.
C: Long-term continuous operation not allowed,
but limited-term operation allowed.
D: High risk of injury. Operation not allowed.

Representative zone boundary values

Using a relative evaluation standardtrend management

Using the normal condition as a reference, threshold values for caution and hazard conditions are set.
When the caution level is exceeded, monitoring is reinforced, and detailed diagnosis is performed when the hazard level is exceeded. A commonly used factor for setting the levels is as follows: caution level = 2 to 3 times the normal value, hazard level = 2 to 3 times the caution value.
After deciding on the vibration measurement location, measurement direction, and measurement frequency, a time series graph is commonly used for trend management, comprising measurement values and other data.

Trend management diagram


FFT Analyzer Mode

The Need for Frequency Analysis

Machinery usually comprises a variety of vibration
sources such as motors, gears, bearings, fans, etc. When devising measures to minimize vibrations and when trying to locate the causes of problematic vibrations, measuring only the magnitude of vibrations often will not provide enough information. It is also necessary to perform frequency analysis, in order to determine
which types of vibrations exist and what their levels are.

As shown in the illustration, the locations where vibrations occur will affect the vibration frequency.
Frequency analysis makes it possible to pinpoint
vibration sources with greater accuracy


Vibration amplitudes are shown for each frequency.
The time waveform is divided into constant intervals,
and FFT analysis* is performed for these intervals.
A sine wave will have only one line spectrum, but complex machine vibrations will show peaks at various frequencies.FFT (Fast Fourier Transform) analysis is a type of frequency analysis that is particularly suited to analyzing machine vibrations.

This shows the variations over time at the location of the

It provides information that is not available from the spectrum display, such as whether the vibration is normal or impact related, whether it has shifted upwards or downwards, etc.


FFT Analyzer Mode Applications

Product Quality Control

When testing products on manufacturing lines for unusual vibrations, frequency analysis can be very helpful. For example, when targeting a specific frequency, it can be determined whether there are vibration components in the adjacent frequency range. Using the frequency spectrum with a known good product as reference, comparative analysis can be applied to pass / fail evaluation.

Comparison to reference spectrumOverlapping of stored data


FFT Analyzer Mode Applications

Precision Diagnosis of Rotating Machinery

Precision diagnosis is used to determine the cause of problems as well as the extent, location etc.


Bearing problems will cause a significant increase in acceleration values.
As seen in the example, envelope analysis shows the peaks at equal intervals.
When the size, number of rolling elements, axis rotation speed and other parameters are known, the primary frequency of the lined-up peaks will provide information about the problem location.


When there is a misalignment, large vibration components that are an
integral multiple of the rotation speed will appear in the axis direction.
The type of bearing joint affects the multiplication factor. In the example shown here, there are large vibration components with a factor of 3.


When there is an imbalance, large vibration components at a frequency equal to the rotation speed will appear in
the circumferential direction.
Vibrations of other frequencies will be largely absent. The vibration amplitude is proportional to the imbalance magnitude. At higher rotation speeds, the vibration amplitude is proportional to the square of the rotation frequency.

Measuring the Resonance Frequency of a Structure

When an external force at a frequency close to the resonance frequency is
applied to a structure, strong vibration will occur. This can lead to breakdown of
machinery, product quality degradation, and other problems. In order to guard
against such risks, measuring the resonance frequency is very important.
In the example shown at right, multiple resonance frequencies at 8 Hz, 98 Hz etc. exist.




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