Vibration Analyses on Vibrating Tables provide Important Quality Assurance Parameters

  MSR165 Data Logger for shock and vibration with microSD card. The memory card can be replaced during operation.
A data logger on the vibrating table: Here the concrete is compacted in the formwork by means of vibrators that have been mounted underneath the table. Source: Creabeton Matériaux AG
Measurement taken on a powered gear drive for a concrete mixer, using an MSR165 data logger. Source: Creabeton Matériaux AG

MSR165 Data Loggers as ideal Diagnostic Tools

The ambient conditions during the manufacture of concrete elements for the construction industry are harsh. The vibrating tables, which are often used in the process, were supposed to be monitored by means of special miniature data loggers with respect to their vibration parameters, in order to ensure an optimal product quality of the concrete elements.

Where are miniature data loggers used?

In a concrete element production line, vibrating tables have the task of compacting the concrete that has been cast in the formwork or moulds, by means of mechanical vibrations, thus ensuring that it is of a high quality and homogeneous in its inner structure. When filling the formwork, it is possible that the base material is distributed unevenly; therefore, it is necessary to ensure that air or excess liquid can escape from the concrete during the subsequent vibration process. In the case of free-standing containers, a tapping effect intensifies this process.

By changing the displacement or the vibration frequency during operation, the vibration characteristic is infinitely adjustable and can be adapted to the required conditions. Depending on the consistency and curing time of the concrete, it may be necessary to initiate the vibrations during filling or after the casting process has been completed. If such a vibrating table, which is powered by means of a motor and an eccentric disc, does not work one hundred percent, the manufactured concrete elements may not have a homogeneous distribution of the contained base materials.

Avoiding manufacturing problems

During the manufacture of the concrete elements, it is possible for blowholes (air bubbles) to form or the material to be distributed unevenly. For instance, the coarse, heavy components might settle at the bottom. This would, of course, reduce the quality of the concrete elements and must therefore be avoided at all costs – primarily in order to prevent expensive consequential damage and warranty claims with the associated loss of image from the outset. Faulty eccentric discs or defective drive motors can be the reason for a malfunctioning vibrating table.

Data loggers quickly detect malfunctions

Such vibrating tables are, for example, used by Creabeton Matériaux AG, a company that manufactures balcony elements, stairs, angle elements etc. from concrete, to name but a few. In order to ensure that the vibrating tables function properly, Creabeton performed numerous practical tests using the MSR165 miniature data loggers of the Seuzach-based technology company MSR Electronics GmbH. These small data recording devices are mounted on the four corners of the vibrating tables, i.e. exactly where the drives are located. Fitted with special sensor technology elements, these loggers are 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. The digital 3-axis acceleration sensor starts recording data either when an acceleration threshold is exceeded or at a set time. 32 measured values 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. The recordings can also be taken over longer periods of time as both the recording capacity of the loggers and their battery performance can be adapted exactly to the respective applications by means of different logger type variants.

The diagnosis is made quickly and reliably

Evaluation diagram of a measurement taken on the vibrating table: The vibration parameters are depicted clearly in the three axes as a function of time. Here you can see that the movement occurs only in one axis (upper curve) – a correct function. Source: Creabeton Matériaux AG In the production of the concrete parts at Creabeton, these miniature loggers are used in order to record the vibration parameters at specific measuring points of the vibrating tables, at different intervals for a period of 10 seconds each. These parameters are subsequently stored in the logger. In addition, numerous useful and informative measurements can be taken on the gear drives of concrete mixers. The acceleration values in the three axes and their frequencies are recorded. The subsequent data analysis on the PC initially provides graphics diagrams of the vibration parameters as a function of time; any potential time or mechanical deviations of these vibration parameters can be calculated from the provided measured curves. All this then allows the experienced engineer to draw an accurate conclusion as to the possible error source in the electrical or mechanical components of the vibrating table. Ultimately, a particular benefit of recording the vibration parameters arises from the fact that potential malfunctions of the vibrating tables can be identified and eliminated very quickly, which has a long-lasting, positive impact on the product quality of the manufactured concrete elements. Incidentally, these data loggers came to the attention of Creabeton Matériaux AG some time ago, when practice-oriented target values had to be defined for the mechanical vibration parameters.

Conclusion: The compact MSR165 miniature data loggers can be used to easily record and store vibration parameters on vibrating tables for precast concrete elements, even under harsh ambient conditions. The data that can be derived from this quickly shows whether there are any malfunctions in the mechanical elements or in the drives. The resulting optimisation measures ultimately lead to a consistently high manufacturing quality with all its economic and technical benefits.

About Creabeton Matériaux AG

Creabeton Matériaux AG, which is based in Lyss, is the market leader in Switzerland as a manufacturer and supplier of concrete products. In 2000, four firmly-anchored regional companies merged to form Creabeton Matériaux AG and became a part of the Vigier Holding Group. In 2001, Vigier Holding was integrated into the French Vicat Group. Every year, Creabeton processes in excess of 60,000 orders and delivers concrete products with a total weight of 300,000 tonnes. The product range includes prefabricated concrete products and systems for landscape gardening, construction projects above and below ground, as well as infrastructure.

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