Adaptable filtration system developed for laser processing

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The Fraunhofer IWS researchers used a multi-adsorption system to investigate the adsorption behavior of competing gases to find suitable filter substances. (Image: Fraunhofer IWS)

Fraunhofer IWS and its partners have developed an adaptable filter system that efficiently removes the air pollutants generated during laser and plasma welding.

The technology could also be used for additive manufacturing in the future.

Microparticles and harmful gases are released when metals are welded with lasers or plasma.

According to Fraunhofer IWS, while activated carbon filter systems are the standard currently used by metalworking firms, which retain volatile organic compounds, substances such as formaldehyde, nitrogen oxides and problematic sulfur compounds are also released during laser/plasma processing.

‘No system has so far been available that removes all [these] substances from the air equally well,‘ the institute said in its announcement of the new filtration system.

Therefore, as part of the MultiFUN project, Fraunhofer IWS and its partners (including filtration firm ULT) have developed what it says is the first flexible filtration system that effectively binds a variety of air pollutants at the same time.

The system consists of several exchangeable modules. Each filter level contains a filter medium specifically designed to remove particular substances from the ambient air. In addition to activated carbon, the filter system also uses zeolites, porous polymers and metal organic frameworks.

According to Fraunhofer IWS, a distinguishing feature of the new system compared with conventional filter systems is its sensor monitoring, which automatically detects when the filter medium is saturated with substances and needs to be replaced. The status is displayed by coloured LEDs separately for each filter level and pollutant class. This means that only the filter level that is saturated needs to be replaced.

Blinded by automation

Jens Friedrich, group manager for gas and particle filtration at Fraunhofer IWS, explained that as production becomes increasingly automated, less attention is being paid to emission protection due to people not permanently being present at facilities. ‘This is a problem, because employees do occasionally have to enter the facilities to carry out repairs and maintenance, and to monitor the quality of the products,’ he said. ‘In such cases, employees are not aware of quite how polluted the air in fact is.’

In addition to welding facilities, such automated environments in which the air isn’t being adequately cleaned also include additive manufacturing facilities, according to Friedrich.

‘In additive manufacturing using 3D laser robots, significant quantities of microparticles are released,’ he continued. ‘These are deposited and pollute the room as well as the workpieces. The particles can contaminate high-value products. They also represent an accident hazard, if people slip on the pellets accumulated on the floor.’

Together with its partners, Fraunhofer IWS is therefore also working on developing a similar filtration system that is specifically designed to filter out pollutants and substances released during additive manufacturing.

‘Our institute has expertise in laser processing, in materials and in the development of entire systems,’ said Friedrich. ‘This makes us the right partner when it comes to the development of such filter solutions.’

He also believes there is a growing need for filtration systems that remove various substances from the air in the production and recycling of batteries. This is particularly the case because metals such as nickel, manganese and cobalt are used here, which can form compounds that are hazardous to health even at very low doses.

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