Condition Monitoring

Application of Ultrasound Technology

The most important applications of vibration- based measurement technologies are related to the monitoring of rotating and reciprocating machinery. Vibration analysis and technical acoustic investigations are predominantly carried out in the frequency range up to 20 kHz.

However, many technical and physical processes generate sound and vibration at higher frequencies. Most current ultrasound testing instruments enable users to access relatively simple parameters, such as sound level, recorded and converted by narrowband sensors and electronics. This limits the informative value of ultrasound measuring results, since most physical processes generate ultrasound in a broad frequency range.

Foreword

Christian Probst
Sensor Developer
SONOTEC Ultraschallsensorik Halle GmbH

Therefore, an approach has been developed for broadband monitoring of processes up to frequencies of about 200 kHz. Vibration and ultrasound can be considered closely related to each other. Ultrasound provides early indications of bearing distress and material wear, which are useful for analysing the trend of machinery state. Vibration and ultrasound can be used in combination with each other.

An important prerequisite for the exploitation of the complete physically-based information in acoustical broadband signals is the use of proper sensors. Therefore sensors have been developed on the basis of new piezoelectric composite materials. The physical and construction principles enable acoustic measurements in a wide frequency range. The frequency characteristic of the sensors can be linearised to a certain extent.

This will be demonstrated by means of some significant applications, such as friction, process monitoring of a wafer dicing machine and the diagnostics of bearing damage. The novel sensors are part of a new modular and scalable measurement concept that includes data acquisition and treatment, the use of algorithms in real time and improved calculations and predictions.

Christian Probst