Advertorial Privatbahn Magazine 06/21
As an innovative manufacturer of springs for rail transport, one of the main driving forces for Grueber is the continuous development of the latest technologies. In addition, there are market demands for ever-higher quality along with simultaneous efficiency and – increasingly – the demand for sustainability and environmental compatibility.
That’s why for more than 20 years, Grueber has been researching and developing environmentally-friendly coating systems that specifically meet the requirements of rail transport spring technology. Now, in a development partnership with Mäder, one of the leading manufacturers of industrial coatings and surfaces (www.mader-group.com), Grueber’s designers have developed an innovative coating that has what it takes to set new standards.
Supporting and steering elements of the rail vehicles: Helical compression springs.
Market and makers in constant motion.
The main challenges for the Grueber developers are the extremely long periods of use for the products that extend over decades and several 100,000 km, as well as the constantly changing loads, movement and friction on the parts. This places immense demands on material quality, and especially on the surfaces. In particular, the spring end coils contact each other with varying loads at different lengths. The coating layers must be able to withstand these stresses permanently and at the same time provide sufficient elasticity to guarantee optimum adhesion to the substrate of the spring. This is also the difference to static elements, with which high layer thicknesses are possible. And last but not least, rail vehicle manufacturers expect minimal life cycle costs and the best possible aesthetics, as the springs are highly visible elements that influence the overall appearance of the trains.
How to make more from less together.
The task was therefore to develop a coating system that meets the highest technical requirements, does not cost more than the previous system, has minimal coating consumption and overspray, and passes a 1000 h spray mist test without damage.
In joint test series, springs with extreme geometry, very tight winding ratios and coil spacing were dip-coated in the Mäder coating system. The first results were already excellent and were then further optimised.
“Based on the successful test results with Mäder, we modified our spray-coating line to the new system on a trial basis. As standard, the 2-component coatings run via flow cells and mixers, which is of course not necessary for the 1-component coating but required a temporary conversion. The accelerated drying at 60 °C previously carried out could be deactivated. Spring types such as those used in freight car bogies were coated,” explains Grueber director Matthias Nettmann about the successful test series.
The result is therefore an application that achieves a high increase in efficiency and quality with a low investment in control and few technical updates. The energy required for drying is completely eliminated, the thin-layer coating causes significantly less overspray, and the durability of the surfaces ensures high sustainability and enables simpler and more environmentally-friendly packaging.
Preliminary approval from DB-Systemtechnik has already been granted for the coating system. Together, Grueber and Mäder continue to work on perfecting the system for series production. Further joint tests and test series in the coming years – for example in potash transport – will yield further findings and optimisations.