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In theory, belt conveyors in the mining and quarrying industry are ideal “candidates” for implementing concepts of operating condition monitoring and predictive maintenance. The belts run continuously, the environmental conditions are unfavourable (dust, humidity, day/night temperature changes etc.). There are typical irregularities (skewing, dropping) and also characteristic damage patterns (uneven wear, belt cracks etc.). And the need for continuous condition monitoring is also given – after all, in most cases there is no alternative or redundant system that can quickly take over the task of material transport in the event of a belt stop.

Desire: practical operating condition monitoring

Nevertheless, the solutions for condition monitoring that have been available on the market up to now are, strictly speaking, only partial solutions. The classic is an electromechanical belt-alignment switch with a two-stage signal. If the belt runs off-centre in a defined area, the switch emits a warning signal and service is called for. If the misalignment increases, the switch causes the belt to be switched off. Alternatively, individual (drive) components such as gear motors and roller bearings can be equipped with condition monitoring systems (CMS). An example: Sensors are installed on the bearings of the rollers that detect irregularities and thus enable the early detection of bearing damage. But: Here, only individual drive components are monitored and not the belt itself.

Reason: Reduced maintenance effort on belts

The fact that ScrapeTec Trading GmbH, Kamp-Lintfort/Germany, a globally active specialist for the optimization of bulk material conveying systems, has now developed a system for the holistic detection of operating conditions is ultimately due to the excellent function of another ScrapeTec product. In most plants with belt conveyors, it is not only common but necessary to inspect the belts daily. In particular, the dust that is also abrasive or sticky, depending on the material being conveyed, which is generated during material transport and penetrates the moving parts of the belt drive such as rollers and bearings, causes the belts to fail more frequently. In addition, the dust generation is often unacceptable for the employees. With the contactless and thus wear-free AirScrape system (Figure 1), ScrapeTec has developed a concept that is as simple as it is effective and provides a remedy. The system generates an air suction and thus drastically reduces dust formation in the vicinity of the conveyor system, especially in the area of the transfer.

Continuous condition monitoring brings benefits

Many users have already experienced that the installation of the AirScrape system greatly reduces conveyor downtimes and costs in practice. They also benefit from the fact that fewer inspection cycles are required. However, with some of the first AirScrape users, this led to an increase in disturbances and breakdowns that were not due to dust formation, but rather to the fact that there were no longer regular inspection rounds. As a result, irregularities that signalled a defect or even a standstill could no longer be detected at an early stage. It is precisely in this constellation that continuous condition monitoring is recommended – an almost logical development task for ScrapeTec, because the company has set itself the goal of offering the mining and extraction industry intelligent products for everything to do with conveyor belts.

Basis: The PrimeTracker idler pulley

The development work did not have to start from scratch. Because with the PrimeTracker (Figure 2), the basis for the hardware of the operating condition monitoring was already available and the first parameter to be recorded – the belt’s skew – was also already available. The PrimeTracker is a guide roller that detects belt misalignment and automatically compensates for it. Even slight misalignment is immediately detected due to uneven forces that then act on the roller. The cylinder body then swivels automatically so that the belt is steered back to the centre. This works equally well with slight and severe misalignment. In contrast to similar systems, the guide roller can move completely freely in a 360° radius during operation and always maintain 100% contact with the belt (Figure 3). Other advantages of the PrimeTracker include the extraordinary ease of installation, the low maintenance requirements and the protection of the belt edges or the conveyor belt. Sensor technology records the meaningful characteristic values The ScrapeTec developers have integrated robust sensors into this roller, which can be easily integrated into the lower run of existing conveyor systems thanks to its compact design. These sensors record central and meaningful characteristic values, e.g., the belt position, the belt speed and the condition of the belt splice. The necessary evaluation of the data is carried out by a compact industrial computer, which is mounted directly on the belt in a robust and dust proof and splash proof housing. An external power supply is not necessary. Instead, a generator, which is integrated into the castor, generates the required energy. This means that the system is completely self-sufficient.

Data transmission by radio

ScrapeTec will present this CMS system – the E-PrimeTracker (Figure 4) – for the first time at the bauma 2022 trade fair in Munich. The data collected by the sensors and processed by the computer are sent wirelessly, via mobile radio or WLAN, e.g., to a control room or to the laptop or mobile phone of the service personnel. An on-site status display, e.g., with different types of warning or signal lights, can also be realised and in addition. In addition, there will be an app that will give the service technicians on site or the maintenance planners mobile remote access to each E-PrimeTracker in the company’s operating sites.

World premiere

Continuous and comprehensive recording of the operating condition of conveyor belts. This world premiere thus creates the prerequisite for continuously and comprehensively detecting and documenting the “state of health” of a belt conveyor in the sense of condition monitoring and predictive maintenance, with the aim of reporting irregularities and eliminating them as quickly as possible. This transparency with regard to operating data and irregularities significantly increases operational safety and reduces the risk of unplanned downtime. The system continuously records the condition of the belt (cracks, irregularities at the joints etc.) and, just like the basic Prime-Tracker, takes over the automatic correction of belt misalignment. Integration of data into predictive maintenance systems The processed sensor data can be easily integrated into standard predictive maintenance systems. The user can derive the need for service from the transmitted data because the sensors reliably detect changes and issue a warning message at an early stage – before major damage or belt stoppage occurs. In addition, the E-Prime Tracker collects and documents the recorded data. Based on this data, the user can, e.g., optimize the operation of the belt and thus extend its service life. Independently of this, the guide roller continues to perform the task of detecting belt misalignment and compensating for it automatically.

Successful test series In various test series

ScrapeTec engineers have proven the practical suitability of the E-Prime Tracker – in different load situations from 75 to 225 N as well as different positions on the belt and various operating states (infeed, return, with blocked idler). In each test, the parameters determined by the sensor system corresponded to the real measured values.

Thinking ahead with AI

Additional sensors or evaluation of sensor data with AI. At bauma, ScrapeTec is showing a first functional prototype of the E-PrimeTracker that is ready for series production – live, including evaluation and radio transmission of the sensor data. Those responsible at the company see this prototype and the trade fair presentation as a basis for talking to visitors about their concrete requirements for condition monitoring and preventive maintenance of conveyor belts. The developers at ScapeTec have already collected ideas on how to expand this concept even further, e.g., by integrating additional sensors for condition monitoring of rolling bearings. Furthermore, the evaluation of the sensor data could be improved with the help of artificial intelligence (AI). At the moment, however, practical experience is being gathered with the first generation of the E-PrimeTracker.