Optimum painting quality online non-contact film thickness measurement in paint lines

The integrated primerless process is a new painting process for series auto production that reduces emissions as well as energy consumption, space requirements and costs. With this process, primer is no longer applied to the dip-coated body surface. Instead, newly developed base coats are used which take over primer functions such as stone chip protection. After intermediate drying a final layer of clear coat is applied.

To assure paint application with optimum film thickness, bodies are measured after the application of base coat. Should film thickness deviate from specified values, it is thus possible to react quickly and keep paint application within the optimum range.

Film thickness is measured by two robots. They are both equipped with a laser sensing head and carry out a total of approx. 70 online measurements per body. A comparison of these values with those required is shown to the installation user by the station visualization system.

Volkswagen is using the new painting process in production at its factories at Puebla (Mexico) and Pamplona (Spain). For these factories, Dürr supplied the entire application technology with 92 robots including the stations for automated online film thickness measurement with measurement technology by Optisense.

For production of the Polo at Pamplona the new process, referred to at Volkswagen as “Process 2010”, was introduced with the expansion of the paint shop by a top coat line. The new top coat line 2 was installed in an extension to the building in 2006. Since then a total of 27 robots have been painting bodies inside and out with base and clear coats on this fully automated line. During interior painting, 20 handling devices take over the opening and closing of doors, hood and tailgate. In the Ecopaint Checker station, two robots are positioned between base coat and clear coat and guide the laser sensing heads of the film thickness measuring equipment.

Conversion of the existing top coat line 1 to robotics technology and to the new paint system was then carried out. Ramp-up of top coat line 1 has been in progress since April 2008. The paint lines have a total capacity of 90 bodies per hour.