After installing the measuring systems on the machines, measurement data can be collected periodically by using standard procedures. A spectrum analysis and a trend analysis can be executed with this data. The spectrum analysis displays the frequency at which the basic overall value of a machine increases or decreases. These increases or decreases are seen as mechanical errors.

Spectrum Analysis

The spectrum analysis plays an important role for the final advice for a machine. There are several variations in machine behavior known in which no standard is exceeded but there is still a risk to the operational safety. The spectrum analysis eventually identifies the cause. Our specialists can directly address the cause in order to solve possible problems.

Trend Analysis

A trend analysis shows the cause of the change in machine behavior. The average value over a predefined frequency range, the trend value, indicates changes in machine behavior. This is the basis for the advice given by our specialists. This can be a lubrication advice, but also a check of the alignment or replacing certain machine parts such as bearings are possible advices.

Istec uses the applicable ISO standards. Since the ISO standards only uses basic overall values these will never be accepted as guiding. Using spectrum analysis and trend analysis Istec specialists draw up a report, in which a clear picture of the machine’s condition is formed. Also, a clear advice is given with regard to predictive maintenance.


Istec distinguishes different methods for the application of Condition Monitoring and vibration measurements. The type of installation, the risk factor for the process and the existing instrumentation prevail. This results in three categories. The first include machines <50 MW. This includes, for example a sliding bearing or ball bearing. Risk or failure factors can be determined based on calculations for both ball and sleeve bearing machines with monitoring and without monitoring systems. When a monitoring system is present, the data will be used to determine whether there are process-related influences which may alter the vibration behavior of a system.

The second category include machines> 50MW. Measurements for these installations are primarily conducted online. However, offline measurements are also possible. For this type of installations it is very important to collect and analyze as much relevant data as possible and because of the critical importance to the process. The risk or failure factors can be determined based on calculations for both ball and sleeve bearing machines with monitoring and without monitoring.

Istec provides a wide range of measuring systems for different applications. Istec uses a 32-channel measurement system based on the analysis maps of Vibrometer (Meggitt) for the measurement of sleeve bearings. In order to measure ball bearings, Istec uses measuring equipment of SKF. In both cases a database will be constructed in which data is stored and analyzed.

Recommendations on the occasion of Condition Monitoring

Each Condition Monitoring analysis is followed by a maintenance advice. This can vary from corrective actions such as lubrication to the replacement of machine parts. The maintenance recommendations are always justified on the basis of data analysis. This data analysis offers the possibility to obtain more insight in the recommended activities.

After completion of the measurements and giving advice, our specialists will follow-up the maintenance results. They will then determine whether the proceedings have led to the desired results. Also, a better insight into the machine is obtained, resulting in more efficient  data analyses.

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