25 August 2021
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Direct extraction from the welding torch - case study

Is it possible to weld optimally with extraction torches? In the past, they were often considered unwieldy due to the additional extraction elements on the torch, but this image is changing. Based on convincing test experiences, Aebi Schmidt Nederland B.V. decided in favour of a torch-integrated high-vacuum extraction system. Several VacuFil systems from KEMPER are now essential components of the new air pollution control concept at the Dutch manufacturer.

The quality of production shop air was already at an acceptable level, but as a rule, it always tended to be very close to the maximum legal limit. This was clearly not good enough for Aebi Schmidt Nederland B.V. with regard to the health of its employees. The company – located in Holten in the eastern part of the country – wanted to improve the air quality in order to push the concentration of hazardous substances even further below the prescribed limit of 1 mg/m³, particularly in the welding shop.

“One focus at Aebi Schmidt was clearly on improving working conditions”, emphasises facility manager Steven Koenderink. “Air quality was one of the central issues here.” For example, the company wanted to completely ban hazardous substances with lung-damaging, toxic or even carcinogenic effects – precisely those that arise in large quantities, especially in the MIG/MAG welding process used to manufacture the steel-heavy add-on parts from production. Increasing demand for its commercial vehicles for cleaning and clearing traffic areas as well as maintaining green spaces also brought with it higher protective welding equipment requirements.

In the search for a supplier of extraction technology, Kemper from Germany came out on top in the end. The requirements were clearly defined: The cleanest possible hall air in line with the needs of production. For example, the intake systems for the hazardous substances generated during welding should effectively extract them while maintaining flexibility in production. A fixed budget defined the framework for the investment in protective welding equipment.

Kemper put together a customised protective welding equipment concept for Aebi Schmidt. To allow for possible adjustments to the welding shop layout, the manufacturer decided on mobile extraction units. The German company recommended welding fume extraction by means of high-vacuum systems with connected extraction torches. This was due to the following benefits: Firstly, the immediate capture of welding fumes directly at the point of origin and, secondly, the forced tracking of the extraction elements during welding.

As these systems continue to evolve, they are becoming more popular – but to this day their reputation for being difficult to use persists. Despite the initial scepticism, Aebi Schmidt agreed to a comprehensive test. The realisation occurred after just a few days: The VacuFil 250 system used had extracted so much welding fumes that the manufacturer was convinced of its quality within a short time. Aebi Schmidt ordered several units at once.

After the order was placed, Kemper delivered a total of 13 VacuFil 250 high-vacuum systems to the Dutch company. Because they can each be coupled with two extraction torches, Aebi Schmidt employees are able to weld safely at 26 workplaces at the same time. The systems are matched to each other in terms of extraction capacity so that the welding fumes are optimally captured without destroying the protective gas envelope. Unlike other extraction systems such as extraction arms, the welders automatically carry the extraction system integrated in the torch. The system reliably extracts the hazardous substances at the point of origin via an extraction nozzle in the torch. This means Aebi Schmidt achieves high production capacity as well as clean hall air for its employees. Even at high welding intensity, the VacuFil-250 units extract high levels of smoke and dust in continuous operation with a maximum output of 250 m³/h – without any loss of quality, even when two employees are welding at the same time.

Thanks to the particularly high filter quality provided by the KemTex ePTFE filter cartridges with surface filtration, the systems permanently filter out more than 99.9 percent of the captured welding smoke particles. Even particles smaller than 0.1 µm have no chance of escaping back into the hall air after extraction.

Another highlight during the welding process is automatic filter cleaning. This means that the welders do not have to interrupt their work; instead, as the filter becomes saturated, the hazardous substances enter a special disposable container equipped in the systems. The containers are changed contamination-free.

To further save space in production, Aebi Schmidt suspended some systems at relevant positions in the production area. In principle, however, the company retains its flexibility to relocate them at any time and use them on the ground as mobile units.

Additional general ventilation system for the welding robots

In addition, a new general ventilation system that captures welding fumes during automated welding processes also provides protection. Kemper installed a push/pull general ventilation system in the welding robot gantry. This captures the rising welding smoke at a height of around four metres above the equipment. On one side, special extraction openings capture the hazardous substances. A customised ducting system transports them to the central WeldFil filter system installed outside the hall.

After separating the particles that are hazardous to health, the system returns the purified air to the outlets. Because the outlets are positioned a few metres away opposite the extraction openings, a constant horizontal draft is created, which drives any welding fumes that have risen in the direction of the extraction openings. In addition, displacement outlets on the floor help the naturally-buoyant fumes to rise. Recirculation of the cleaned and already heated air also makes this principle energy efficient. A two-way distributor also allows some of the air to be discharged to the outside – and, at the same time, fresh air from outside is also reintroduced.

Thanks to the comprehensive protective welding equipment measures, the air in the hall has consistently improved according to Aebi Schmidt: “We are always amazed at how many harmful hazardous substances the systems actually capture when we change the dust collection containers,” says Koenderink.

“Our welders are very happy with the improved air quality..” As a result, he says, the welder’s awareness of his own health during welding has increased immensely. And after an initial changeover to the new systems, even the handling of the extraction torches – that had a reputation of being cumbersome – is now very easy for the welders.

Extraction torches

As far as effective welding fume extraction goes, the closer to the point of origin the better. This is because if they are extracted directly at the point of origin, they cannot enter the welder’s breathing zone and then escape further into the hall. Accordingly, extraction torches are superior to other systems because the collection elements are closest to the point of origin. However, the extraction capacity must be individually designed for each torch so as not to interfere with the welding process. This depends on various torch parameters. With this in mind, and in order to create more transparency for these parameters that are relevant for torch extraction, the German Welding Society (DVS) has recently launched an appeal for torch manufacturers to make their data freely available on a platform created specifically for this purpose.

On its own measuring stand, Kemper has measured more than 100 torch types from different manufacturers, establishing a database which is part of the VacuFil i high-vacuum product series from KEMPER. At the push of a button, these units provide the correct extraction capacity for the torch in use and automatically adjust this capacity continuously during operation.

Author
FAST magazine

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Kemper UK Ltd

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