Keep your fingers safe with an Austrian invention

Bad accidents with panel saws will soon be a thing of the past thanks to the Felder Group and the Vienna University of Technology.

The panel saw is one of the most dangerous machines in wood-working. Even with the highest care there are still many accidents that often result in the amputation of fingers or the entire hand. There are a number of legally required protective measurements such as shields but in reality, workers often don’t use them because they impede working and the handling of the wood. This is what made the Felder Group think. All existing concepts such as stopping the saw blade within the shortest amount of time have not really been successful with large machinery. So the company came up with a new idea.

Great minds think alike

The Felder Group explains that they had the first ideas for a new solution back in 2013, and by 2015 the company started to develop a completely new safety feature. Soon, the research turned into a cooperation project with the Vienna University of Technology. Robert Tratter, Head of Research and Development at Felder Group, explains why they approached the university: “We were looking for a scientific partner with a high level of research knowledge, combining know-how in all mechatronic fields – mechanics, electrics, electronics and software development. After several preliminary talks with various research facilities the Vienna University of Technology turned out to be the best partner because it met all these requirements and is also an Austrian research partner.”

Thomas Weiler from the Institute of Production Engineering and Photonics at the Vienna University of Technology explains that the first attempts to integrate active safety technology into panel saws date back to the 1960s, but “the existing systems only react once the saw blade makes contact with human tissue. And that is too late, of course. The emergency stop has to happen in an extremely abrupt way to minimise the risk of severe injuries. Such an intensive braking process may damage the sawblade and also requires replacing the entire brake unit.” That is expensive of course and takes up a lot time. Which costs more money. So, the Felder Group and the Vienna University of Technology faced a particular problem: Detecting a dangerous situation quickly and reacting even quicker without damaging parts of the panel saw and thus keeping it operational.

“The decisive idea was to use the saw blade itself as a capacitive sensor,” Weiler says. There is no need for an expensive additional system and no need for complicated motion sensors. These were hurdles that made many companies give up their innovation projects because the panel saw would become very expensive. Similar to an antenna, electric impulses make the saw blade oscillate. And this electric oscillation is influenced whether a human body is close or not. Most people know this effect from old radio sets with a bad reception – you can hear static when you approach the antenna or move away from it.

Robert Tratter, Head of Research and Development at the Felder Group: “The Vienna University of Technology was the best partner for our project.”

“The human body can conduct electricity, thus there can be a reciprocity between an antenna and the human body, at least at short distances,” Weiler says, explaining the new safety feature: “If a finger gets close to the saw blade, it influences the electric oscillation in the blade.” You can tell whether an object with higher conductivity approaches. A wet piece of timber, which would influence the saw blade similarly, would have an effect on a larger scale. “Therefore, a finger has a different signature than a piece of wood meant for cutting. You can detect the difference and trigger an emergency stop.”

Disappearance is the magic word

But an emergency stop would damage the blade and the brake unit, wouldn’t it? Exactly – that’s why the blade doesn’t actually brake at first. So, what do you do when you want to keep two objects apart from one another, the one turning quickly and being very sharp, the other slow and bleeding easily? You make one of them disappear with the help of a software. The blade is lowered by a new electromagnetic actuator principle. “Over the first few millimetres this is being done with 5 g – five times the gravitational force,” Tratter says. This globally patented safety system called PCS Preventive Contact System detects human tissue in the danger zone and lowers the saw blade within a few milliseconds, making it disappear under the panel – there is no contact with the fingers, no injuries, no damage and the saw stays operational for immediate use.

Detection, reaction, action

“In terms of actuator technology, we wanted to a have an extremely short reaction time while ensuring that the entire system remains undamaged and can be put back to use immediately,” Tratter says. Users can continue their work at the press of a button after an emergency stop without the need for any maintenance work.

The Vienna University of Technology already patented its sensors for the detection of human tissue near a saw blade. And it also patented another invention that was necessary to realise the project with the Felder Group: It isn’t just enough to detect danger; the saw also needs to react accordingly with extremely low latency. The Vienna University of Technology also developed a special electromagnetic actuator that makes the blade disappear inside the panel saw. This movement is started in the first millisecond after detecting an approaching finger. Only a few milliseconds later, the blade has reached its escape speed. That means that the blade

The saw blade is protected from all sides with a safety area and disappears if a finger approaches.

moves away from the hand quicker than a human can move towards the blade.

It is important that the blade escapes very quickly yet in a safe and controlled way to ensure that it isn’t damaged and the panel saw is operational again immediately afterwards.

The Preventive Contact System lowers the saw blade with the help of electromagnetic actuators. The entire tool, i.e. the blade including the motor, is kept in position by two permanent magnets. If danger approaches and the system is triggered, the polarity of the permanent magnets is reversed by a strong electric impulse. This creates a tremendous repulsion force that moves the tool with five times the gravitational force underneath the panel and thus away from the danger zone. Before the tool comes to a halt, dampers brake the tool and dissipate the entire kinetic energy. That way, neither the panel saw’s components nor the tool is damaged when the system is triggered. The Preventive Contact System works regardless of dust contamination, even when making hidden cuts or when cutting with a swung-out overhead saw guard. By pressing of a button the saw slowly returns to its original position and is ready for use again. In addition, the system works without wearing any parts and is therefore completely maintenance-free.

Successful cooperation

“Our cooperation with the Vienna University of Technology worked out very well. We first managed to confirm our ideas with preliminary tests and eventually developed a solution ready to go into production after several development cycles,” Tratter says. “The entire project took four years and the cooperation was very positive, constructive and motivational for us. It was a valuable experience for our research and development department and we learned many things for the future.”

The development of the Preventive Contact System received a boost from the subsidies of the EU’s European Regional Development Fund’s programme Investment for Growth and Jobs (IGJ/ ERDF). “Thanks to this financial aid we moved forward a lot

quicker than we would have with our regular research budget,” Tratter says. Furthermore, the subsidies helped to reduce the project’s risk “because there was no guarantee that we would be successful.”

Surprised competitors

The Preventive Contact System was presented at Ligna 2019, the world’s leading trade fair for tools, machinery and plants for wood-working and -processing.

“Our invention surprised everyone when we presented a fully operational machine at Ligna, showing real-life demonstrations every 30 minutes. The new systems of our competitors were often only prototypes,” Tratter remembers. “There are of course a number of patents on the market but most of them had never been implemented. We also wanted to come up with a completely new solution, an innovation that goes far beyond the latest technology. And we managed to do so. The Preventive Contact System is truly a unique product on the market: contactless, extremely quick and non-destructive.”

The Felder Group is constantly working to improve and perfect the system since its market entry to achieve even higher safety for panel saw operators all around the world. Various factors such as regional environmental conditions and different materials have to be taken into account. In addition, the new system has been and is being certified by independent testing institutes.

The demand in panel saws with the Preventive Contact System has been huge, just like the positive feedback on social media after the presentation at Ligna 2019 – particularly from training schools and insurers. That is hardly surprising, says Tratter, when you consider that carpenters and joiners are among the occupational groups with above-average accident risk. Every year, almost 1,000 woodworkers suffer cuts in Austria. More than 50 lose one or more fingers. Operating a panel is by far the biggest source of hand injuries.

But which panel saws come with the Preventive Contact System, and can you actually tell from the outside? “The Preventive Contact System is available as an optional feature of the Format4 Panel Saw Kappa 550 (pictured above). We have been taking orders since the system’s introduction at Ligna 2019. We will start shipping such panel saws in September 2020,” Tratter says. “We want to expand the availability of the system to smaller panel saws step by step. You can only tell if the PCS system has been installed by a logo on the saw and a submenu on the touchscreen.”

Impressive but still only a safety feature

Despite the system’s success Tratter has a warning for curious people who want to test it themselves: “A few members of staff voluntarily tested the Preventive Contact System in their spare time, of course without injuring themselves. But we ask people to refrain from doing so with regards to health and safety regulations. It is a just-in-case safety feature and even if the technology is error-free it is only meant to prevent accidents.”

After all, every woodworker has ten good reasons on his hands to not take any unnecessary risks. ◆

A digital hello from Vienna with Viennese online services

The City of Vienna’s online offer is quite far-reaching: A lot can be done at the click of a mouse from home. The City also has started its own podcast. Now it is up to you to use these services.

Quick official channels

In Vienna, many things can be done quickly online, around the clock without any red tape – the Virtual Office of the City of Vienna is at your disposal. More than 600 websites have comprehensive information on the City’s services including everything on deadlines, costs and necessary documents. If you want to start your own company, for example, you can do all the necessary paperwork online. The offer ranges from registration to moving addresses, from appointing a new managing director to opening new business sites. Other examples for the City’s online services are buying and extending a parking permit, registering your dog or applying for a loading zone.

You can also find the latest waiting times at the passport or residence registration offices of the municipal authorities online.

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Virtual library

The virtual library offers a large range of digital media such as eBooks, eAudios and ePapers that you can lend at the click of a mouse. This service is available to all customers of the Vienna Libraries with a valid library pass. They can choose from around 69,000 digital media around the clock.

These media are available for a number of devices such as eBook readers, tablets and smartphones. A big advantage is the automatic return feature that avoids customers racking up late fees.

In addition, the Virtual Library offers 1,500 eLearning classes from the leading video training provider Lynda to everyone interested in furthering their education.

Try the Overdrive eLibrary of the Vienna Libraries with almost 9,000 English language eBooks and digital audiobooks.

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Photo: City of Vienna Photo: R. Krischanitz

Offers for women

The internet is a major part of everyday life. We are taking part in webinars, chatting with friends and family, listening to podcasts and doing our banking online. But where there is light, there is also shade – how do we react best to online hate speech? How do we deal with fake news? Which pictures should I not post online and which data should I keep to myself? What are the risks of online dating? The free folder “Women Online” by the City’s Department for Women’s Affairs has tips for safe surfing and dealing with sexism, something that women and girls are unfortunately often confronted with online. In addition, there is a list of all ports of call in case of an emergency. It is important that you get help from experts when you need it! Department for Women’s Affairs +43/1/4000-83515

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Treasure of data

The City of Vienna puts all public data (Open Government Data) and services that are not subject to data protection or critical for the infrastructure online – freely available for everyone. This data is shared with all citizens, businesses and scientists. It includes geo data, traffic figures, environmental data, budget figures and statistical data. This opens up a large number of possibilities as this data can by used for the good of many people. Start-ups and businesses, for examples, but also researchers have the opportunity to create innovative solutions without any risks at a low cost. This service is part of the “Open by Default” data initiative of the City of Vienna. It aims for more transparency, participation and close cooperation between the city’s administration and all stakeholders. 300 apps have been created from this open data such as software for the use of public transport or for visualising statistical data.

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New: The City of Vienna Podcast

The City of Vienna uses more and more digital channels to put out information – and now you can even listen to the City: The City of Vienna Podcast deals with the most important urban issues. The public can share their opinion, unfiltered and uncut, on hot topics. The podcast’s first season deals with the Covid crisis. Citizens talk about their experiences, their concerns and their lives. This ranges from inhabitants of a retirement home to business owners in the district of Ottakring who fear for their livelihood. The free podcast is available on all popular audio platforms such as Apple Podcasts, Google Podcasts and Spotify. You can also listen to the City of Vienna Podcast in your browser (Firefox, Chrome, Internet Explorer) or through your RSS reader. If you have installed a podcast app on your smartphone (Android or iOS) you can tune in there as well. The City of Vienna Podcast is the latest addition to the City’s multimedia offer and expands our online offer by another digital component.

Photo: PID/Markus Wache