Higher paint application efficiency reduces material, resources, and energy consumption for a more sustainable production process. With this technology, the speed and spray distance are significantly reduced to enhance the impact of the high voltage, while maintaining a high paint flow rate. In addition, the shaping air is reduced to a minimum and the high-voltage control is adjusted. Dürr is testing the implementation of this painting process in a concrete automotive paint shop in collaboration with interested OEMs. Existing systems have the potential for retrofitting too.  

How the Measures Impact the Process

Reducing the shaping air volume to a range of 90 and 200 standard liters per minute achieves a gentler spray jet. Together with a reduced bell disk speed, energy consumption is reduced. Simultaneously, more paint reaches the body when the spray distance is decreased to approximately 100 millimeters. Two factors contribute to this effect: firstly, a less dispersed spray pattern, and secondly, an enhanced electrical field between the bell disk and body surface, which optimizes the utilization of electrostatic force via a constant voltage. 

Consequently, the atomized paint more effectively reaches the body instead of being lost in the booth air. A paint outflow rate of up to 400 milliliters per minute can be obtained to achieve the required layer thicknesses within the given cycle time. 

Utilizing the atomizers with external charging for exterior painting yields a notable efficiency boost for base coat application, elevating it from 75% to 78% compared with the predecessor model. 

Fast Color Changes Reduce Paint and Rinsing Agent Consumption

This new generation enhances flexibility and efficiency for a more sustainable painting process. The atomizer carries out color changes more because the patented 4-main needle technology not only saves time, but reduces paint and rinsing agent consumption, as well as VOC emissions. 

 Photo courtesy of Dürr.

Three of the four main needles are reserved exclusively for the most frequently used colors. All other colors go through the fourth main needle. Real-world evidence from the automotive sector shows that more than 50% of bodies are painted in the three most frequently used colors.

The technology leverages this fact and provides the three colors permanently via the main needles, which are located directly behind the bell disk. When a color change is due, the system can switch to another main needle within four seconds with no need to rinse and clean the channel. This reduces both paint loss and rinsing agent consumption associated with color changes. If a less frequently used color is requested, it can easily be primed via the fourth channel while one of the three other needles still applies a main color. This means that each color is available for the next body within a very short timeframe.

Additional Savings with the New Paint Booth Concept

Paint and rinsing agent consumption is reduced by 51% in the conventional line setup. This is good for the environment and minimizes process costs. The new atomizer generation is efficient and sustainable in combination with the EcoProBooth. As interior and exterior painting can be performed within a single booth, not only are the color change times shorter but handling times are also lower when compared with the line concept.

Combining the atomizer and the booth can result in savings of up to 91% during color changes by reducing paint loss and rinsing agent consumption. “This is a huge step. Our model calculations are based on a paint shop that uses 24 colors and coats 30 bodies an hour, 230 days a year on a three-shift basis. The amount of paint saved would be enough to paint an additional 15,600 bodies,” says Frank Herre, Head of Application Technology Development at Dürr.

Just Four Robots Reduce Color Change and Handling Times

The system includes up to four main needles, which meets all painting needs ranging from the 4x1C solution for base coats to the 3x2C solution for clear coats. Dürr offers 10 versions, suitable for all exterior and interior painting applications with direct or external charging.