Selective coating without the need for masking

The paint fog formed during spray-painting precesses - overstpray - has to be removed from the air in the painting booth. This is why complex plant technology and high amounts of energy are required in order to condition the air inside the booth. In cases where different colours are used to paint a component, masking has to be carried out manually. This makes the process time-consuming and cost-intensive.

To solve this problem, Fraunhofer IPA has developed MicroCoat, a system that enables users from a wide range of industries to coat their products loss-free without the need for masking.

The key component of the system is a 6-axis robot capable of extremely high repeat accuracy. The robot is located inside a booth with controllable volumes of incoming and exhaust air, thus enabling solvents and particles to be removed effectively.

A range of different application modules can be used with the robot, e.g.:

The coating material is applied to the surface with round or flat nozzles. Alternatively, it can be applied using transfer materials, such as foam or fleece. Quantities are regulated via a metering unit, with the result that very fine lines can be generated with sharply demarcated edges. Therefore, multi-colour coatings can be applied to components with different geometries without the need for masking or de-masking.

Piezo-jet valve
This application module generates free-flying droplets of the coating material over a surface area of several millimetres or centimetres, which then impact with great accuracy onto the surface. In contrast with conventional ink-jet printing methods, a broad spectrum of coating materials with low or high viscosity can be applied. The use of ceramic components also allows abrasive coating materials to be processed.

Precision atomizer
We have extended the airbrush atomizer used in graphic design applications by adding a linear drive for the paint needle and a magnetic valve to regulate the feed of atomizing air. This means that it can be adapted for use with a robot. Coating materials can be micro-dispensed in the range of approx. 100 mPas and applied extremely accurately. The jet can be narrowed down to 2 mm with a blurring range of 30%. The finely atomized spray also enables very thin layers < 1 μm to be applied uniformly and precisely.