Condition Monitoring Services for Industry

Vibration Analysis

VA forms the backbone of any condition monitoring program. One reason it is so extensively used is because unlike certain other CM techniques, VA is applicable to all  sections of a machine train whereas some CM methods can only be carried out on the motor, the gearbox or the fan, pump etc. as you can see from the diagram below.

People have been doing vibration analysis long before anyone had heard of 'Condition Monitoring'

The old screwdriver trick is one of the longest standing methods of CM however, it is very subjective. What one person may consider excessive is another persons smooth!

But, using modern instruments, vibration levels can be very accurately recorded and compared to ISO and British standards for vibration levels.

However, VA is most powerful when we can also compare it to previous readings from the same point and trend how quickly a problem is developing.

Vibration analysis is also very powerful at identifying exactly what type of fault is developing on which component. How? well, all rotating and reciprocating machinery will vibrate. The different components will vibrate at their own rotational frequency. Information about the condition of that machine is contained within the vibration waveforms. As a fault develops, so the waveform will change and increase in amplitude. Vibration analysis is a non intrusive method of collecting these waveforms and using a mathematical process invented by some old French mathematician geezer (Joseph Fourier 1768–1830), this information can be broken down into its component frequencies. Analysing this information can give prior warning of component failures thereby reducing the risk of unexpected breakdowns.

VA, the Efftek way

Three types of radial reading are taken at each collection point on a machine, usually in the vertical plane;

Standard Velocity Spectra detect a wide range of faults such as looseness, misalignment, mass imbalance and insecurity. These spectras can also be converted mathematically in the software into acceleration spectras.

High Frequency Band (HFB) acceleration readings indicate poor quality lubrication and early stages of bearing and gear defect.

Enveloped Signal Processing (ESP) extracts rolling element bearing defect information from bearing housing resonance to give an excellent indication of bearing condition. This is THE MOST important technique available and should always be included in any CM program as it identifies bearing defects well in advance of a problem showing up in a standard velocity spectra. Download our VA Case Study presentation to see how accurately it picked up a developing motor bearing defect.

In addition, an axial velocity reading from each section gives a complete picture of machine condition.

These are trended in the CM software to determine if any problems are developing and if so, how quickly, and are graded according to severity. The VA report will explain exactly what problems are developing and suggest remedial action which should be taken to prevent the machine from failing during production. An example VA report can be found on our downloads page.