Schmersal has set itself the task of supporting customers not only in the introduction of future technologies as part of the digital transformation, but also in reducing the_{carbon footprint} along the value chain. The company starts with the material that most safety switches are made of: Plastic.

However, the fundamental difficulty with products in the field of machine safety is that new, environmentally friendly approaches to product design or the use of materials must not compromise the quality and, in particular, the safety functions of the safety switching devices in any way. This means that the optimized devices must also comply with the standards, their suitability must be checked and confirmed by certification.

In order to achieve progress in this area, Schmersal has been working with universities and research institutes for a long time, for example with the Lüdenscheid Plastics Institute. A current project involves the use of recycled material in the manufacture of safety switchgear with a plastic housing. "Our aim is to use 20 percent recycled material in the switches manufactured using the injection molding process," says Matthias Banaszek, Head of Value Management/Innovation Manager at Schmersal. "Over the past two years, we have therefore collected around 30 tons of sorted material from production waste, such as sprues or start-up residues, i.e. unsuitable first components that accumulate when a new production batch is started."

Up to 25 % regranulate possible

According to the UL organization, which awards globally recognized safety test marks, a regranulate content of 25% is possible in safety switches. "This is approved for in-house processing. However, as this involves a great deal of effort, we have this carried out by an external, certified processor. Unfortunately, the UL regulations state that an admixture is only permitted with increased testing effort. However, we are working closely with UL to find a joint solution," continues Matthias Banaszek.

The TÜV would also certify safety switches with recycled content - provided that proof can be provided that the recycled material used has no influence on the quality of the safety functions. To this end, the Plastics Institute is carrying out a comparative test with Schmersal switches: Switches made purely from virgin material are examined in comparison to switches consisting of 80 % virgin material and 20 % recycled pellets. A series of parameters are analyzed using standard-compliant test methods. These include, for example

• The Charpy impact strength test in accordance with EN ISO 179-1, which is used to characterize a plastic at high elongation rates,
• Density measurement in accordance with EN ISO 1183-1,
• the IEC 60093 test method for contact resistance to describe the electrical insulation behavior.

The aim is to prove that the switches made of mixed material withstand adverse environmental influences just as well as those made of pure new material. If the results of the comparative test from the Plastics Institute are available and meet expectations - i.e. there are no quality impairments due to the use of mixed material - the next step is for the switches to be certified by TÜV. After that, the way would be clear for series production of the switches with regranulate content. This would make Schmersal the first manufacturer to use recycled material in the production of safety switches.

Plastics from alternative raw materials

Matthias Banaszek, Head of Value Management and Innovation Manager at Schmersal: "I could also imagine using natural polymers for many other packaging materials and components."

© Schmersal

Another environmental project came about indirectly via the Lüdenscheid Plastics Institute: Schmersal has joined the German innovation network 'Poly4Nature' as an active partner. This network is funded by the Federal Ministry for Economic Affairs and Climate Protection and managed by the Lüdenscheid Plastics Institute. The aim of Poly4Nature is to produce plastics from alternative raw materials and using alternative processes, for example by using natural fibers or primary products from natural recyclable or waste streams. These materials are intended to replace previously used fossil materials in order to achieve_{CO2 reduction} or_{CO2 neutrality}. This is because the building blocks for the production of plastics are carbon compounds that are obtained from crude oil or natural gas. Both the extraction and transportation of fossil fuels such as crude oil or natural gas and the production of plastics release considerable amounts of climate-damaging_{CO2 emissions}.

As a network partner, Schmersal has agreed a specific project with Poly4Nature: the development of biodegradable protective plugs based on alternative raw materials. These protective plugs are used to cover screws and screw-in holes and are used by Schmersal in their hundreds of thousands - exclusively for the transportation of switches. As soon as the user removes the switches from the transport packaging, the protective plugs are disposed of. "The protective plugs are not safety-relevant components. It is therefore much easier to use alternative materials here," explains Banaszek. "I could also imagine using natural polymers for many other packaging materials and components, for example for accessories such as slot covers, screw plugs or the transport lock that we use for our AZM40 solenoid interlock."

The alternative plastics for these packaging materials could, for example, be of marine origin, such as algae. Poly4Nature sees further possibilities in the "use of renewable carbon from pyrolysis processes, lignin-based material systems, the use of natural fibers or primary products from natural material or waste streams. These materials should not only replace previously used fossil materials, but also provide products with new functions depending on possible property profiles, or at least offer CO2 reduction or neutrality." However, it is also important to discuss new value chains of natural origin that do not compete with agricultural land and the food industry in contrast to previously known materials.

It remains to be seen whether the Schmersal protective plugs will actually be made from algae in the future; the project will run until the beginning of 2026.

The article was based on documents from Schmersal.