Acceleration data logger MSR165 for fault diagnosis of defective sensors — During the product development of a new saddle stitcher for magazines, the Muller Martini company used MSR165 acceleration loggers. Image source: Muller Martini

Reading out the data or charging the battery is done by clicking the clip onto the four gold contacts on the top of the housing. The clip is read out via the USB slot.

Acceleration Data Logger MSR165 for Fault Diagnosis of Defective Sensors

Case study Müller Martini AG

During product development of a new saddle stitcher for magazines, Muller Martini AG, a global player in the field of print finishing machines, discovered the failure of sensors. The cause of the failure was identified using small acceleration data loggers from MSR Electronics GmbH.

Author: Fabian Acklin, Technik Sammelhefter TSH-1, Mechanical Engineer Muller Martini AG

The faulty components in the three-knife trimmer for the new saddle stitcher were edge sensors which detect the position of the products immediately before they are cut. They had previously worked without malfunction, but had now failed during the test phase at customers’ premises. The analysis of the defective sensors showed mechanical damage in the sensor element.

Vibrations were suspected to be the cause of the damage. However, since there were many different causes for this problem due to the very dynamic motion sequences in the machine, ways were sought to record the existing vibrations at the sensor. The aim of the measurements was to determine the possible sources of the disturbances as precisely as possible in order to draw the right conclusions. The measures implemented were also to be quickly checked for their effectiveness.

After a brief Internet search, online configuration on the website of the Swiss technology company MSR Electronics GmbH and a telephone conversation with the consultant there, the MSR165 series miniature data logger was defined as a suitable measurement device.

On troubleshooting: miniature data logger for shock and vibration

The MSR165 data logger for shock and vibration is capable of performing 1600 measurements per second for up to five years. Its core sensor element is a high-resolution 3-axis digital accelerometer. It is ideally suited for vibration measurements and shock monitoring, for example for transport monitoring, fault diagnosis and load tests.

Shock monitoring is possible with the MSR165 up to ±15 g or ±200 g, 32 measurement values are recorded before the event. The logger’s memory capacity of over two million measurement values is sufficient to record over 10,000 shocks – even over very long periods if necessary. By means of a microSD card, the capacity can even be increased to over 1 billion measured values (10,000,000 shocks). All data can be quickly transferred to a computer via USB or microSD card. The MSR165 is supplied with PC software for configuration and analysis of the data as well as the MSR ShockViewer software. The powerful evaluation software is used for advanced analysis and graphic display of the data acquired in shock mode, as well as for automatic report generation.

Measurements and results of investigations

The data logger was attached to the affected sensor of the new machine with double-sided adhesive tape (figure 2). During operation, accelerations of up to 218 g were measured in the x-axis (figure 3). In comparative measurements with the data logger on the old machine (figure 4), the results showed only about 35 g acceleration (figure 5). It is therefore understandable why the sensors on the new machine were damaged.

By switching off individual subsystems, it was quickly established that the massive accelerations were caused by the pneumatic stops. These stops were now analysed in more detail and all differences were listed.

Cause of error could be eliminated quickly

The hose length between valve and stop made the difference. With the same hose length as on the old machine, the accelerations are now again of a comparable order of magnitude. At the same time, the sensor manufacturer optimised the sensor for the relatively high accelerations that still exist. Since then, no sensor has failed.

Conclusion: The cause of the failure of the sensors on the new machine could not have been found within one working day without the data loggers. From this it can be seen that these loggers are an optimal and above all time-saving aid for fault diagnosis in the event of mechanical problems with shocks, vibration and acceleration on machine elements.