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For the first time, interior painting of vans and trucks with the ESTA process

07/10/2007

15% less paint consumption due to ESTA atomizers by Dürr

Bietigheim-Bissingen, July 10, 2007 – For the inside painting of trunk compartments at vans and trucks as well, highest quality control requirements are valid. At passenger cars, a relatively small part of the interior is to be painted, since large areas of the surface are covered later. In addition, these inside painting areas are situated favorably at the doors and hoods. At automated painting installations, robots open the doors and hoods. This way, the painting robots reach the planned areas without problems.

At vans and trucks the access to the interior is not quite that simple for the painting robot. The often quite long bodies have no or only limited access possibilities for painting robots on the side. Only through the tailgate is it possible that robots reach the entire interior.

For this purpose, there are two methods. First, the body is transported backwards over a stationary painting robot, or, second, and that is the more frequently used solution, the robot is mounted to a pivoting arm and is swiveled into the body. In addition, the pivoting device can be on a traveling axis. In total, up to eight movement axes are involved, so that all areas of the interior can be reached and painted.

Usually, air atomizers are used for paint application. With these atomizers, in part also double atomizers, large paint volumes can be yielded (800-1000 ml/min). The kinetic energy is relatively high with this kind of atomization, therefore the atomized paint causes "overspray". That means that not all paint droplets deposit at the desired place of the body. In addition, overspray leads to soiling in the booth, since the paint mist escapes from the interior of the body through body apertures such as windows and doors. The transfer efficiency of such installations is usually 35 to 50%.

Because of these disadvantages, air atomizing procedures are increasingly superseded by the ESTA procedure. The paint is atomized with less kinetic energy. By charging the paint with high voltage, the fact that the paint droplets follow the electric lines of electric flux to the grounded body is additionally taken advantage of. This way, the transfer efficiency reaches 50 to 80%. That means: Paint consumption and soiling are reduced while the quality of the painting is increasing.

In a paint shop in Poland, Dürr atomizers of the model EcoBell2 are now being used for the first time for interior painting jobs at vans and trucks with direct charge. The two parallel lines are each equipped with one Dürr EcoRP8 painting robot with swing arm. The bodies are conveyed on a skid into the waiting position of the interior painting zone in stop-and-go mode. After the preceding body has been painted, the robot swings from the painting position and clears the way for the waiting body. In this time, the purging and pre-painting process for the next color takes place and, if necessary, the atomizer cleaning with the fully-automatic atomizer cleaning device EcoBell Cleaner by Dürr. As soon as the body has reached the painting position, the robot swings into the painting position. With the traveling axis and the other movement axes of the robot, all necessary positions for the inside painting can be approached. For the different motor vehicle models, the corresponding movement and painting processes are programmed in offline simulations and transmitted to the robot controller.

Essential parameters in the lines are the paint flow rates of 250-700 ml (predominantly 400-600 ml), the shaping air consumption of 350-600 Nl/min (predominantly 500-600 Nl/min), the rotating speed of the atomizer with 50000 min^-1, a constant high voltage of 50 KV and a cycle time of 96 seconds. Compared with the air atomizers used before, the paint consumption could be reduced by 15% by the use of the ESTA and the painting quality was clearly improved.

The Dürr Group is one of the world's leading suppliers of products, systems, and services for automobile manufacturing. Its range of products and services covers important stages of vehicle production. As a systems supplier, Dürr plans and builds complete paint shops and final assembly facilities. Dürr also delivers cleaning and filtration systems for the manufacture of engine and transmission components as well as diagnostic and balancing systems for vehicle components. Around 90% of Group sales relate to business with automobile manufacturers and their suppliers. The machinery, chemical, pharmaceutical, coating and aviation industries are also major customers of Dürr.