Painting is a very important part of car manufacturing process. A poor paint job will leave customers unsatisfied and can even lead to premature rusting. Audi is known for its excellent paint job, but it comes at a price. Audi is offering a two-colour finishes on a couple of its models and that is a nightmare for factories. Or at least used to be, because now Audi uses an “overspray-free painting” technology.
You can buy and Audi A4 Sedan and A5 Coupé with a black roof. It looks rather stylish, but it is not easy to do. You see, two-colour paint job immediately becomes a two-stage process. At first, car has to be masked off. For example, if the roof is going to be painted first, the rest of the car has to be covered with paper and tape. This takes a lot of time. Then in the second stage when the rest of the car is painted, the roof has to be masked. This results in a huge pile of wasted masking materials, an elevated production cost and a lengthy process. But until now it was unavoidable.
Last year in Spring Audi started testing of a new “overspray-free painting” technology. Overspray is a normal part of a spray-painting process, which comes about because in order to cover the entire surface evenly you have to finish spraying after it. This is exactly why masking is needed. But now a robot-controlled high-precision instrument measures the laser-brazed seam between the car’s roof and side panel frame and another robot sprays a special paint right to that line without any overspray or mist. Fine strips of paint are applied with millimeter precision. Take a look at the roof of this A5 Coupé – the main panel is black, but the door frame next to it is green. And it was achieved without masking.
To achieve this sort of precision Audi uses a very accurate spray-painting robot, which keeps its nozzle very close to the surface. No mist, no overspray and no unnecessary buildup of paint. This is harder to achieve than you think. The black paint is prepared specifically for this process to create perfect viscosity and flow. The software that controls the robot has to take the speed of the nozzle into account and the edges so that an even surface would be achieved. In the future, other colours together with this technology will allow for extensive personalization options.
But this is not just about reducing production times and costs. It is also helping the environment. First of all, a lot of masking material is saved, which reduces waste. Secondly, there is no overspray, which means that wasted paint is also reduced, which is good for Audi, but also good for the environment. Finally, this process should also require less energy.
Audi is only now starting to use this overspray-free process in its production. Who know what this technology will be able to achieve in the future. Hopefully, multi-colour customization options are on their way.