What does it mean when a laser cabin is safe?

Equipment used to weld car parts can present a hazard. However, this danger is regulated by internationally defined standards. You might think that this is a rather boring task, but for Erwin Heberer, one of the pioneers in the further development of laser safety cabins, it was a great passion.

Lasers impress Heberer. Without people being able to see it, the laser focusses the light, which generates enormous energy. This energy melts metal, but also harbours risks. ‘One problem with lasers will always be that they reflect. Hotspots form and can burn themselves into anything,’ says Heberer. Lasers are often used in industry today, for example in car manufacturing, as they replace many traditional welding tasks. However, this technology also increases safety requirements, as these hotspots are dangerous and can even burn into walls, optics or metal parts - and in the worst-case scenario, even into human skin.

At the headquarters of system manufacturer FFT in Fulda, as elsewhere, protective cabins are set up around the laser welding systems. Heberer enters one of the grey booths, in which two car doors are attached with hydraulic clamps. Two orange-coloured industrial robots from Kuka bend over these parts, at the tips of which are cubes with lenses. These lenses focus the laser beam that welds the car parts together. Cables running along the robot arms guide the welding wire and transport the laser beams.

Heberer has been an expert in laser safety for over 20 years and has inspected numerous laser safety cabins worldwide - at major car manufacturers in Germany, but also in the Czech Republic, Spain, the USA and China. The cabins may be geographically far apart, but the basic structure of the safety cabins is the same worldwide, as the physical properties of the laser are the same everywhere. A uniform standard is usually used to determine the safety of laser cabins: 60825-4, which was established by the International Electrotechnical Commission (IEC).

The standard requires laser systems to be checked every eight hours. Heberer ensures that the cabins are safe within this period by measuring the radiation outside the cabin. This must not exceed 50 watts per square metre. The standard also contains detailed regulations, such as how to check whether the protective wall can withstand the laser. Heberer checks many aspects, including the door construction and ventilation, but also details such as the correct labelling of the rear of the laser safety barrier. Such small details are crucial, as they can determine whether the wall can withstand the laser beams. Those who adhere to the standard can be sure of meeting the latest safety standards. This promotes the confidence of manufacturers, customers and the employees who work with the lasers.

Standards also have legal significance. The standards of the IEC and the German Institute for Standardisation (DIN), for example, do not only apply to laser technology

In the 1980s and 1990s, when industrial lasers became increasingly cheaper and were therefore more widely used, there was also progress in the regulations for their safe use. In 1989, 76-year-old Erwin Heberer, a trained metalworker, began building laser safety cabins in his small company when a company from Munich commissioned him to do so. Heberer quickly asked himself whether these cabins were really safe. And so the development began.

Tests in Aachen and Copenhagen showed that the cabin walls broke through much more frequently than expected. Heberer also discovered that conventional test methods did not correspond to practice. Together with Joachim Franek, he realised that the heat flow from the laser focal point to the side had not been sufficiently taken into account. Most of the tests were carried out with small lasers and the results were then extrapolated linearly to industrial lasers. ‘However, this was not practical for higher-power lasers, which behaved differently. They depend on the spot size,’ he reports.

Heberer also made a strong case for emphasising the dangers of laser reflections. He showed pictures of burnt tissue samples and thus emphasised the dangers posed by the scattering of the laser beam. In the laser cabin at FFT in Fulda, he still shows a metal plate with burn marks. Even today, holes can still occur due to unforeseen hotspots. However, we are now better prepared for these dangers.

Heberer, who was active in standardisation committees for noise protection even before his work in the laser protection sector, campaigned intensively for the reform of the laser standard. In the 1990s, when he was working with the International Electrotechnical Commission (IEC), the reform of the testing process for laser cabins became his major concern. His proposal was finally accepted in Milan in 2000.

Standardisation work is a lengthy process, as Heberer explains with a list of proposed changes. For him, this work was a passion, as it helped him to solve important technical challenges and improve the safety of laser cabins worldwide. He still encourages active participation in standardisation processes today. After all, by getting involved, you can not only help shape the state of the art, but also ensure that your own products are recognised internationally as a standard.

However, Heberer criticises the fact that some large companies in Germany are less involved in standardisation committees because they are afraid of giving the competition an insight into their innovations. But he is convinced that it is an advantage to be involved in the long term.

Thanks to privately organised standardisation, Germany took on a leading role as a standard setter during the economic miracle. This remains of great importance for companies orientated towards the European and global market. The German ‘bottom-up’ model also ensures that standards are developed for which there is a real need.

Erwin Heberer does not view China's involvement in international standardisation organisations as fundamentally negative. When major companies participate in standardisation, global interoperability is strengthened, which benefits everyone. For this reason, his final appeal is: ‘Get involved in standardisation!’

Source: Frankfurter Allgemeine Zeitung, p. 16, no. 65 (18 March 2025)