Concrete marking for type features on concrete sleepers defy wind and weather

Ten freshly produced sleepers roll slowly, close together, over the chain conveyor of the final inspection. On a bridge above them, five print heads of the REA JET Large Character Inkjet Printer DOD 2.0 are waiting. Light scanners detect the leading edge of each approaching sleeper and send the print start signal to the print heads, which mark the concrete sleeper in up to three places. Each print head receives the data for serial printing directly from the Moll plant database: The REA JET controller is connected to the control system of the end line via Ethernet. "This fully automatic marking is an unattended, digital process and ensures correct marking in production real time, eliminating manual errors," says Ralf Giesecke, responsible for control technology and automation at the plant.

Up to 1,200 sleepers roll off the production line at the Biebesheim plant every day. These are standard and special sleepers that go to railroad and infrastructure companies throughout Europe - based on framework agreements with large companies and groups, but also for individual orders from small, private customers who particularly appreciate the special range.

Since 2019, five REA JET DOD 2.0 systems have been marking each individual sleeper. "For a larger special lot of Deutsche Bahn Netz AG, which we were entrusted with manufacturing in Biebesheim, sleeper markings beyond the usual trade show were agreed. They were intended to make the type features recognizable even from a distance, for example for a crane driver," says Giesecke, explaining the origin of the collaboration. The lettering has to be large and still legible even after long periods of outdoor storage. "There have been similar requirements in our plants from time to time in recent years," says Giesecke, looking back to the time before the collaboration with REA Elektronik. "The resistance of the print to the weather, especially UV radiation, was a requirement that could only be satisfactorily solved with REA."

Machine markingof concrete replaces manual work

Initially, production employees in Biebesheim applied the data by hand, using stamps or spray paint and stencils. But it was fast clear that this could not be a permanent solution - for health and safety reasons alone. The large character printing systems from REA JET Systems now solve several requirements at the same time. They work with special inks that adhere well, dry fast and are weather-resistant. REA's drop-on-demand technology (DOD) only releases the ink droplets via the nozzles of the print heads when they are needed for the printed image. This makes the technology low-consumption and also ensures that the maximum workplace concentration (MAK) of solvents is reduced to a minimum. And all of this is permanent and reliable, even in the harsh and dusty environment of concrete production.

"The fast-drying REA ink and the cement dust in the plant are very demanding conditions," says Sven Kopriwa, sales representative at REA Elektronik. "But the print heads of our DOD 2.0 large character inkjet printers are very robust. In addition, with our combination of ink supply and cleaning, the entire system can be easily flushed, which also increases the operational readiness of the print heads." REA JET Large Character Inkjet Printers Generation 2.0 are among the world's best large character inkjet printers for harsh, dusty or humid production environments. DOD systems are ideal for marking building materials, bricks, bagged goods, shrink hoods, insulating materials, steel profiles and many other materials. REA JET's in-house coding and marking technologies have been further developed and optimized over the years.

Connection to the company database

For each sleeper package that reaches the final inspection, the REA JET controllers receive their marking data from the production database, store it in their buffer and pass it on to each of the five print heads simultaneously, which print it on each individual piece in the group and are then ready for the next data package. "Because the different markings for each threshold type come from the higher-level control system and its database, human error sources are eliminated," says Ralf Giesecke, citing another key advantage of the REA Coding and Marking Systems. The print heads used at Moll can apply information in up to four lines of text. They are also aligned to the passing sleepers so that they work accurately despite the different dimensions of the various types of sleeper. Integrated collision protection protects the print heads from damage if the sleepers are not aligned correctly.

"Regardless of the industry, our versatile range of standard components gives us the flexibility to configure an individual printing solution for each customer that meets their requirements and spatial conditions," says REA employee Kopriwa. In the concrete component industry, too, every company - even every sleeper manufacturer - works with different technology, under different environmental conditions and with individual requirements for concrete marking. "Whether for existing production lines or a new building, with multi-line lettering or logo print, in clean or rather dusty environments: we will find the right, tailor-made REA Coding and Marking Solutions."

And the two partners already have the next one in mind for Biebesheim: the marking of each sleeper with a Data Matrix code is intended to advance the digitalization of production and further increase process-reliability with the machine-readability of each individual sleeper ID.