Detecting machine trouble quickly and accurately

MSR Data Loggers record all kinds of “vibration fingerprints” – comprehensive analysis on the PC

The following report was published in the SMM Schweizer Maschinenmarkt magazine, July 2015 edition

Today, all kinds of production machines, machine tools and transport machines use a complex drive technology, in order to accurately generate linear movements in three axes or rotational movements with high efficiency. The characteristic oscillation or vibration patterns, which occur with all mechanical movements, can be used within this context in order to monitor and optimise the entire drive technology with respect to their mechanical/electrical parameters. In the process, miniature data loggers can provide significant, and in particular, time and cost-saving support.

For many years we have tried to record, store and analyse the characteristic oscillation, shock and vibration parameters of all kinds of machines and drives in a time-saving, cost-effective and user-friendly manner. This helps to optimise the efficiency of the mechanical drive trains and to specify appropriate target or average values for these parameters. On the one hand this is used to document the quality and to present the performance parameters; on the other hand, in the case of deviations from vibration and oscillation patterns established as “good”, it facilitates the early detection of emerging damage.

Securing the “vibration fingerprints”

Such a “mechanical vibration fingerprint” is the ideal reference value in the case of an emerging error, for instance if, a ball bearing in a gear drive is faulty and therefore results in a deviation from the normal vibration amplitudes or frequencies. At any rate, the recording of mechanical faults by means of characteristic vibration patterns – if realised at an early stage – contributes to the prevention of costly outage times “in the field” or production downtimes. Ultimately, the recording of characteristic vibration parameters on all moving machine elements and drive systems is an absolute must today.

The characteristic oscillation, vibration or shock parameters are ideally recorded without any relevant additional mechanical load. This means that the sensor or the element recording and storing the mechanical parameters, should be very small and light in order to prevent any corruption of the recorded vibration parameters (so-called artefacts). However, appropriate analysis software is equally important as it quickly and clearly provides the experts with the desired fault diagnoses and therefore forms the basis for the accurate and timely rectification of issues.

Mini data logger as a long-term measurement laboratory

Within this context, the MSR165 miniature data loggers of the Seuzach-based technology company MSR Electronics GmbH have proven successful in many fields of application of the automation and machine building sector, as well as in the electrical engineering, transport, automotive and aerospace industries for some time. In particular the MSR165 data logger, which is merely the size of a thumb, specialises in applications in the recording of oscillations, shocks and vibrations. Its sensor technology core element is a high resolution 3-axis digital accelerometer. This, coupled with the connected evaluation electronics, enables the robust data logger to take 1,600 shock and vibration measurements per second in all three axes (x, y, z) for up to five years. In addition, the temperature, humidity, pressure and light intensity can be measured and recorded.

If equipped with an appropriate memory card, the memory of this small sensor and recording module is capable of storing over 1 billion measured values. The evaluation is carried out on the PC by means of software that is user-friendly, yet provides detailed analyses. In order to be able to ensure the optimal utilisation of expensive production machines, the MSR165 can, for instance, be used to monitor vibrations of servo-axes or to measure vibrations on the turret of a production machine. These recordings enable the user to draw conclusions with respect to whether a tool is defective, a machine is overloaded, the drive is not running optimally, a service is required or whether vibrations are transferred to other machine elements. The latter, for example, is highly relevant to industrial tools, as the service life can be increased greatly by eliminating all kinds of vibrations.

Fitted with its sensor technology elements, this logger is capable of recording shock loads and vibrations of ±15 g in the three axes; however, an extended working range of ±200 g (g = acceleration of gravity 9.81 m/s2) is also available. The latter working range is useful if stresses are to be recorded, where very large forces occur suddenly. Of course, the characteristic “good” vibration patterns can also be recorded and used as a basis for comparison in the event of a fault.

The digital 3-axis acceleration sensor starts recording data either when an acceleration threshold is exceeded or at a time set by the user. 32 sets of measured data are recorded even before the shock event takes place, in order to ensure that the history of the shock can be examined during a g-analysis. As a result, the user not only knows that a shock has occurred but also identifies the exact development and the cause of this damaging mechanical impact.

Recording data for months

The MSR165 data logger, which works self-sufficiently in long-term operation, has extremely low power requirements due to its high-performance 3-axis accelerometer (150 microampere power consumption, 13-bit measured value resolution). Thanks to its rechargeable 900 mAh lithium-polymer battery, the unit can already monitor shocks over a period of up to six months by default. In order to satisfy the demand for an even longer recording period, MSR Electronics GmbH offers two additional options for long-term power supply to the data logger: For a longer recording period, the MSR165 can be equipped with replaceable batteries (3.6 V, 2 x 7700 mAh, Li-SOCl2). The batteries are stored in an industrial-strength, waterproof aluminium case. Another option of increasing the recording period of the MSR165 by up to six times is to use the “MSR Power Pack”. It is an autonomous charging station with a capacity of 5000 mAh that can be used to recharge the internal battery of the data logger during operation. The charging interval of the unit can be adjusted individually: 24 hours, 7 days or 30 days.

Conclusion: MSR miniature data loggers can be used purposefully in all areas of the machine building sector to detect and record all kinds of oscillation patterns, vibrations or shock loads without artefact effect. The evaluation of the recorded parameters facilitates the quick and cost-effective fault diagnosis and subsequent mechanical or electromechanical optimisation. Ultimately, significant time and cost advantages and not least, pluses with respect to the quality and reliability of all kinds of machines and drives, can be achieved.