Robotics specialist ABB has developed painting robots that use an inkjet-type printer head with over 1,000 individually controllable nozzles, enabling higher accuracy and transfer efficiency in the automotive paint shop, the company claims. The new robots have been designed to meet end-customer demand for vehicle individuality, particularly in the SUV segment. Typically, special OEM finishes demand extensive masking and repeated paint applications, adding significant time and cost during manufacture.
Transfer efficiency refers to the ratio of sprayed coating that adheres to the substrate versus the overspray that ends up as wasted material. “Removing overspray from a factory paint process may not sound that impressive – until you appreciate how many benefits are created as a result,” said Joerg Reger, managing director of ABB Robotics Automotive OEM. “By eliminating the creation of overspray, we can dispense with masking between different colors, we reduce paint wastage to zero, and all that with greatly reduced operating costs. The flexibility of programming means the nozzles can also produce complex graphics in a single pass.”
Called PixelPaint, the system avoids paint flow, but instead uses the multiple nozzles to apply individual droplets of paint to a surface, much like digital pixels. Variable droplet control, combined with a novel inkjet design incorporating 1,000 nozzles within a 100-mm (4-in.) spread, facilitates faster and more accurate high-resolution printing of two-tone and customized designs directly onto vehicle bodies. The result is “a high level of detail,” according to Reger.
The droplets can be applied in sizes ranging from 20 to 50µm at a rate of over 1,000 droplets per second. This enables more precise control of paint film thickness and also of overlapping, to achieve required ultra-sharp definition of paint edges whilst eliminating wasted material. Because 100% of the paint is applied to the bodywork surface, the typical 20% overspray associated with typical electrostatic painting is said to be avoided.
Cost savings
Reger explained that PixelPaint permits a second color or design to be applied within an existing paint line without extending cycle times or adding manpower. It also avoids installation of a special line or supplementary paint shop, supporting reductions in both capital and operating costs. Environmental performance is also improved as no paint is lost to drainage.
PixelPaint can be used with ABB’s IRB 5500 painting robot or with a high-precision handling robot, more commonly used for seam sealing. ABB’s software package includes a user-friendly programming tool called RobotStudio to enable offline programming for easy set-up and testing.
“Using PixelPaint enables auto manufacturers to produce multiple, complex designs very quickly, meeting consumer tastes for individuality without incurring extended production time and costs,” Reger said. “With a customized paint job, cycle times are reduced by 50 percent through the design being executable in a single pass. When this is combined with the other benefits such as improved utilization of manual workers, we envisage very significant improvements in productivity.”
ABB has also introduced a compact interior paint station, which combines 12 robots to offer a space-saving alternative to traditional robotic interior systems. It is claimed to reduce the footprint of current paint booths by up to 33%. The system can be integrated with other door, hood and trunk opening robots with the company’s new IRB 5500-27 7-axis robot. An enhanced working angle with improved reach reduces robot population.
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