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    Pin-sharp coat­ing

    Coating of industrial components is a common yet complex procedure.Depending on the situation, selecting the best equipment for the application is critical. Global equipment manufacturer WALTHER PILOT has collaborated with material manufacturer Dörken to develop an optimized process enabling the coating of parts with extreme accuracy and without the need for masking.

    Matthias Mandal (WALTHER Spritz- und Lackiersysteme GmbH), Tobias Kleyer (Dörken)

    Corrosion resistant coatings are applied to larger parts by spray application, which often times results in excessive amounts of overspray. This requires a large percentage of the part to be masked even if you are only trying to coat a very small area. As a result, in mid-2020 WALTHER PILOT and Dörken started working on a development project that was completed in March 2021. The result: a zinc flake coating application applied by an automatic spray gun, controlled by a robot, yielding highly reproducible results with little to no overspray.

    How does the new coating procedure work?

    he zinc flake material is fed from a compressed air-filled pressure tank through an automatic spray gun. These automatic spray guns are precision devices designed to atomize the coating with air passing through fine separate air intake channels and then further refined with high precision nozzles and air caps. Parts are coated with finely atomized zinc coating using as little as one bar of air pressure. A unique aspect of this procedure is that the material application has pulse control, which allows small quantities of coating in a small droplet size to be applied in a very thin film. This thin and even application is extremely important for the alignment of the material pigments that are critical for superior corrosion protection.

    The challenge was to ensure that the material keeps its pigments in lamellar form when sprayed and does not block the automatic spray gun, while at the same time applied evenly and accurately to the various geometries at a coat thickness of just 10µm. We used experience gained from industrial dot application and line marking to create a new applicator developed specifically for this task.

    Reaching objectives together

    The primary goal of this project was to achieve superior coating results without the need to mask the part. Masking is relatively expensive and can be an intricate process. The goal was to remove this requirement for highly complex parts. Through interaction and experimentation, the development teams from both companies designed a workable solution. Multiple customers who are coating rotationally symmetrical parts such as wheel bearings, brake discs or threaded parts are successfully using the new process. This complete package was developed to enables users to enjoy simple process control with maximum benefit to their manufacturing process.

    Good to know:

    The following objectives were achieved resulting in:

    • reduction of investment and maintenance costs
    • most efficient use of material
    • reduction of material loss
    • removal of all masking cost and effort
    • robust, automated process