Preventive maintenance of weighing systems

Saving costs, increasing system efficiency

The technological insides of scales have become increasingly complex over the past years. A consequence: When a scale fails, elimination of the problem takes longer and is likely to be more expensive. The better way: Make sure that your scale does not fail at all. The technical term is 'Preventive Maintenance'. This concept promises substantial cost savings and increased system efficiency. HBM provides the required components.

Significant progress has been achieved regarding the structure and technology of scales over the past years. Hence determining the state of individual components or assemblies is becoming increasingly difficult, because up-to-date systems have significantly more weaknesses than older machines. In addition, design engineers no longer tend toward over-dimensioning but instead rather develop lighter systems that require less space. As a consequence, many components have become more sensitive to wear and failure.

Maintenance and repair concepts primarily aim at ensuring the highest possible technical availability of a system. An increasing number of companies have come to realize that maintenance is not just a necessary evil or merely an originator of costs. When a scale fails, a company not only has to face the costs resulting from potential repair or replacement of defective components. The company will not be able to continue its production while the system is down. The ever increasing pressure resulting from the competition for quality and efficiency forces companies to introduce maintenance and repair systems to avoid undesired system failures. This applies in particular to industry and truck scales as well as process systems using gravimetric weighing systems.

Preventive maintenance - Definition and objectives

The German DIN 31051:2003-06 standard (see also DIN EN 13306) defines preventive maintenance as the combination of all technical and administrative measures as well as management measures during the life cycle of a unit under consideration to maintain or restore its operational state and thus to ensure that it is capable of performing the required operation. The German standard distinguishes four basic measures: maintenance, inspection, corrective maintenance (overhaul - repair), and improvement.

Maintenance: Measures taken to delay the degradation of the existing volume of wear.

Inspection: Measures taken to determine and evaluate the actual state of a unit under consideration including the determination of the causes of wear and deriving the required consequences for future use.

Corrective maintenance (overhaul - repair): Measures taken to restore the operational state of a unit under consideration, except for improvements.

Improvement: Combination of all technical and administrative measures as well as management measures to increase the functional safety of a unit under consideration without modifying its requested functionality.
Preventive maintenance is particularly important where the failure of technical systems might result in irreversible damage to human life or major economic damage. The primary goal is to prevent system failure. Other objectives can be:

  • Increasing and optimally utilizing the life of systems and equipment,
  • Enhanced operational safety,
  • Higher system availability,
  • Reduction of failures,
  • Predictive cost planning.

The DIS2116 digital scale electronics as an example for preventive maintenance

Preventive maintenance uses the information at hand to determine the dates for required maintenance work. By introducing a preventive maintenance concept the following objectives for system efficiency are set:

  • Minimizing downtimes during a specific period of time,
  • Short repair times on the weighing instrument,
  • Minor impact of downtimes on business processes.

However, for achieving these objectives it is not sufficient to merely define and perform maintenance tasks; smooth spare parts supply is very important as well. Weighing systems featuring preventive information or direct error messages can be quickly restarted and therefore provide an economic head start.

HBM's DIS2116 digital scale electronics permits predictive maintenance through automatic status messages to a higher-level control system, which positively affects operating costs.

DIS2116 digital scale electronics

The DIS2116 digital scale electronics enables legal-for-trade and manipulation-proof weighing systems to be implemented, e.g. truck scales. A 256-bit key is used for encrypted data transmission from the load cells to the scale electronics. DIS2116 has been designed for use with type C16i digital load cells using a 32-bit processor.

Consistent use of digital technology, from the scale electronics down to the sensor, enables individual weighing systems or plants comprising multiple weighing systems to be conveniently managed. Furthermore, interference resulting from external influences (EMC) is virtually impossible. In addition to electronic off-center load error compensation within few minutes DIS 2116 features an SD card which functions as a legal-for-trade alibi memory and enables all settings, e.g. calibration parameters, to be captured.

Installation of the DIS2116 digital scale electronics is no problem for system integrators. Only a few software commands are required to integrate it into higher-level systems. Moreover, many interfaces are available for convenient connection to higher-level systems: RS-232 ports for connection of a PC, PS2 and USB ports for connection of a PC keyboard and printer.

An automatic status message sent to a higher-level control system is one of the convenient functions provided by the DIS2116 digital scale electronics. Based on the easy installation of the scale electronics, this function offers many benefits.

Longer service life because maintenance can be planned and performed in time

Due to the fact that the weighing system sends status messages to the control system, maintenance intervals can be planned at an early stage. Based on information available from the weighing system, e.g. wear or failure of cable insulation, the optimal dates for maintenance work are determined. Timely and predictable maintenance results in a longer service life of the weighing system.

Faster sensor exchange, maximal system efficiency

An automatic status message to a higher-level control system enables the respective sensor to be quickly localized and replaced in the event of a failure. Shortened scale repair times and reduced downtimes positively affect the system's efficiency. Incidents such as several hundred refuse collection vehicles waiting for several hours at the waste disposal site because of the failure of a truck scale will therefore be a thing of the past.

DIS2116 Weighing Indicator

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