Two robots are varnishing both sides at the same time © Handl Maschinen
After an in-depth analysis of each of the group’s production sites, Stora Enso decided to install the coating line in Ybbs. The main requirement for the plant was the ability to process full-size panels with a format of 16 by 3.45 m and a possible weight of up to 5,000 kg.
"When it came to possible surfaces, it was important for the customer to be prepared for all current and future requirements," Dr. Peter Handl from Handl Maschinen in Wels recalls and explains that the entire range of technical and decorative surfaces – from industrial to visible quality – was required in the specifications. When it comes to technical surfaces, protection against insects and moisture is very important.
The technical plant design
The individual processes in the line are separated from each other by means of special buffers © Handl Maschinen
"Based on the specified requirements, it quickly became clear to us that a fully flexible plant design was necessary," Handl explains. The individual materials have to be applied on different sides and edges. The various pumps are already equipped with the most important coating materials and are programmed to distribute them to the individual color wheels. Using robotics, the materials are applied on each side and edge. Stora Enso can select each surface separately, making it possible to apply different coatings on interior and exterior surfaces. The necessary data come from the company’s own ERP system.
The process
Once the panels have been milled, they are transported horizontally to the infeed lifting device on a roller conveyor. There, the plant operator connects them to the suspended crossbeam. Based on the panel ID, the necessary parameters are retrieved from the ERP system and transferred to the plant control computer which was supplied by Finiture of Padua/IT. Next, the panels are erected automatically by the lifting device and placed on the conveyor. From this point on, all processes happen fully automatically. In the entire line, the suspended crossbeam is identified via RFID. After they have passed through the infeed buffer, a 3D scan of the panels is done which serves as basis for the automatically generated spraying programs. When entering the spray booth, any dust is first removed from the panels. In the hermetically sealed spray booth, two robots with specially designed spray applicators coat one or more of the elements which are hanging from the suspended crossbeam. After that, the panels are left to dry in the warm air dryer, which extracts moisture with the LDP system. Then, the elements either enter the exit buffer or they are sanded automatically before they are coated again. Finally, the elements are lowered back onto a horizontal roller conveyor by the lifting device at the exit and leave the line.
Tried-and-tested system
"Over the past 15 years, we built many fully automated robot-assisted varnishing systems for windows and doors, and we were able to build on this experience. We learned a lot from every CLT varnishing line we built, and part of this experience has even been included in patents. It quickly became clear to us that the individual processes in the line had to be separated from each other by means of special buffers in order to achieve high efficiency. This applies not only to the individual processes, such as scanning, coating, drying and sanding, but also to loading and unloading. It is also important that lifting devices are available at all times. We ensure this with a special storage system," Giovanni Sedino, owner of Finiture, explains.
The line was installed in the second and third quarters and is currently being put into operation (see article Making the industrial coating of CLT even more ecological).
