Apply coatings with sharp edges - without any overspray at all

(September 2020/OM) - In almost every industrial sector, the number and diversity of workpieces that are coated is growing. In order to be able to paint the diverse components more efficiently than before, Dürr has developed a new technical process that applies paints over a wide area or in simple patterns with sharp-edged color edges - and does so entirely without overspray.

The EcoPaintJet applicator was awarded the German Innovation Prize this year and is now available for general industry in an easy-to-integrate set. Adler has already developed paints adapted to the new application technology.

In wood processing, shipbuilding, electronics manufacturing and many other industrial sectors, the surfaces of products and components are coated to protect them or give them color. Until now, this has involved a great deal of effort on the one hand if the surfaces are to be coated with sharp edges. This is because the surfaces either have to be masked or foiled manually. In addition, a lot of waste is generated by adhesive tape and paint is lost due to overspray. Dürr's new overspray-free application set eliminates both of these. EcoPaintJet, the innovative applicator in the set, is already being used successfully in automotive series production. Here, the new Dürr technology has enabled the painting of color-contrasting car roofs since 2019, completely without masking.

The EcoPaintJet applicator coats with sharp separation without paint mist. This increases painting efficiency and opens up more possibilities for companies in product design and goods transport. Instead of glued-on film, for example, decorative surfaces can be protected for transport by the targeted application of film paint. This can then be easily removed again.

New options are also available for the function and design of products. Window frames, for example, can be given a weather-resistant coating on the outside and a decorative or other color coating on the inside by means of the release coating. Decorative effects can be easily achieved on furniture fronts. "The overspray-free application set combines edge-to-edge application, enables fast color changes and individual surface design," says Holger Beiersdorfer, Vice President Industrial Products at Dürr, summarizing the advantages.

The most important component of the overspray-free application set is the paint supply, combined with the cleaning and press-on process. The EcoPaintJet controls this via three valves. The heart of the applicator itself is a nozzle plate which, depending on the version, generates several dozen parallel paint jets. These can be activated or deactivated at any time to start or interrupt the coating process. In contrast to painting processes with paint spray guns or high-speed rotary atomizers, this process does not require atomizing air. This means that no paint mist is produced, which has to be filtered out of the booth air at great expense, as is the case with conventional processes.

Another key difference from conventional atomizers is that the width of the paint web can be adjusted via the applicator's application angle. In this way, a 30 to 50 mm wide paint web can be achieved. Narrower web widths can also be produced by adjusting the nozzle plate. The speed of the applicator and the solid content of the coating control the desired coating thickness. Paint-saving application techniques are particularly important for large areas. However, even with airless guns or high-rotation atomizers, up to a quarter of the material used is lost. Recovery costs time and energy and only works with certain types of paint. So-called pouring, in which the excess paint is collected in containers, avoids overspray but does not allow rapid color changes. Other techniques for surface design, such as applying foils or trim, often involve a great deal of manual effort.

The new Dürr technology eliminates all the disadvantages of the individual processes and makes painting faster, more cost-efficient and more environmentally friendly in all industrial sectors. "This means that our technology is even of interest in areas where automated painting processes had not even been considered before," says Holger Beiersdorfer, pointing out further potential applications. Austrian paint manufacturer Adler is driving the new application technology forward together with Dürr and is implementing colorless and pigmented coating solutions that go beyond the usual paint requirements and are precisely tailored to the special features of this technology. "Innovative and environmentally friendly, water-based products have been developed for this visionary application technology, which ensure maximum durability and at the same time visual individuality, not only for sheet goods," says Dr. Albert Rössler, CTO at Adler, who is convinced of the new coating technology.

► Dürr Systems AG

► www.durr.com

Adler-Werk Lackfabrik Johann Berghofer GmbH & Co KG
www.adler-lacke.com