Edge-sharp and overspray-free painting of complex automotive body parts

Thanks to a further development of the EcoPaintJet robotic system, it is now possible to paint very complex body surfaces in the automotive industry, such as vertical surfaces or A- and C-pillars, without masking.

Contrast roof painting with the Dürr EcoPaintJet was the first series application of overspray-free paint application in the automotive industry. Now, with the further developed Pro version, the robotic system can also paint very complex body surfaces such as vertical surfaces or A and C pillars, as well as apply individual design elements - without masking and fully automatically. The precise interplay of high-tech components from paint application, robotics and software ensures maximum precision, greater energy efficiency and resource-saving use of materials. The new process has been used in automotive series production since 2022. EcoPaintJet Pro can process solvent-based and water-based 1K and 2K coatings.

Contrasting colors on roof surfaces or A- and C-pillars, stripe designs or intricate elements such as lettering: The design requirements for two-tone coatings in automotive production are constantly increasing. At the same time, manufacturers' expectations of the systems are growing. They are expected to apply contrasting coatings flexibly with different colors and types of paint to diverse, even vertical surfaces, without changing the body design or interfering with the production process - and to do so at the lowest possible production and environmental costs.

Dürr has further developed its EcoPaintJet with the Pro version for the demanding task of applying all paint types in two-tone lines fully automatically without overspray: The special robotic system with the overspray-free applicator and the modified paint supply process includes all the necessary components to meet the high demands. In addition to an innovative cleaning process, these include fully automatic inspection of the blast pattern, camera sensors for measuring the car body, and various software tools for robot control, for generating the robot program, and for adapting the paint program to the real vehicle with accuracy down to a tenth of a millimeter.

The heart of the system is the EcoPaintJet Pro applicator, which, unlike a rotary atomizer, applies the paint with the aid of a filigree nozzle plate. Several dozen, barely visible individual nozzles with a diameter of around a tenth of a millimeter apply the paint to the body in parallel jets from a distance of up to 25 millimeters. 100 percent of the paint lands on the surface without loss, making two-tone painting possible more quickly and conserving resources without masking.

The fact that the nozzles can be closed and opened independently of each other in a fraction of a second opens up completely new design possibilities for car manufacturers. The new application principle means that design elements such as trim stripes or contrasting colors can be applied to the bodywork fully automatically. The EcoPaintJet Pro can both paint over a wide area and apply patterns - a direct transition is also possible.

Right from the start, Dürr designed the EcoPaintJet Pro so that color changes are possible without any problems. It is designed in such a way that paint cannot be deposited at any point. This is crucial for a fast and low-loss changeover between two color tones.

This feature is also important when working with 2K coatings, as these harden quickly. If the smallest residues were to remain after rinsing, the fine nozzles could become clogged. With the EcoPaintJet Cleaner, all cleaning and rinsing processes can be carried out in a closed system so that no waste enters the booth environment - the paint booth no longer requires overspray separation.

The complex geometries of the car body parts to be painted place high demands on the 3D measurement and programming of robot paths. DXQ3D.onsite supports operators in configuring the process parameters; the software automatically calculates the painting paths along which the applicator hovers over the surface. An initial measurement detects and compensates for any inaccuracies in the conveyor system or body shell. A second sensor mounted on the robot measures the deviation of the car body to be painted from the reference pattern. The robot controller adjusts the painting paths in real time. The speed and tilt angle of the applicator are controlled so that the paint is always applied evenly and no overspray occurs. The development of the software tools is a continuous process. Enhancements and optimizations are added regularly.

Not only in new plants, but also in existing plants, EcoPaintJet Pro offers automotive manufacturers the opportunity to integrate overspray-free applications. Various processes are available for this purpose, which can be integrated at different points in the paint shop. For example, the contrast coating can be applied to the intermediately dried basecoat or as a single-layer topcoat on top of the baked clearcoat. Masking-free two-tone coating with EcoPaintJet Pro has far lower space and energy requirements than a comparable conventional line. Calculations show energy savings of up to 32 percent (based on the entire paint line). As a result, up to 33 kg of CO2 can be saved per car body.

Dürr's new process is of great advantage both in terms of production costs and environmental compatibility: without overspray, paint separation is no longer necessary and the rest of the car body no longer has to be masked with film, so large quantities of waste are saved. Added to this is better utilization of the paint shops. "Printing instead of spraying is the future of automotive painting," Dr. Lars Friedrich, President & CEO Application Technology Dürr Systems AG, is certain. "Even with vertical surfaces, we can do without overspray and masking altogether. In terms of cost efficiency and sustainability, Dürr has thus taken another step in the right direction with the EcoPaintJet." (OM-06/23)