A solution for different colours and recipes in the paint installation

Arctic, a Romanian company producing electric appliences such as refrigerators and washing machines, was looking for an automatic solution to paint over 27 types of parts with 2 different colours and recipes.

Arctic uses a two-component finishing paint from Akzo Nobel. This has to be thinned to be applied correctly onto a plastic surface with a 25µm film.

The ratio recommended by the producer was 7:1 for paint with hardener, and 2:1 if you take (A+B):C, volume C being larger than B. Arctic used to apply this with a low exit 100 cc/min gun. For applying the thinner, they used a Graco ProMix 2KS station and mixed A+C with 10:1 ratio. However, in this case, it was hard to measure component B.
 

One recipe for (A+B):C

To avoid human error in the mixing process and to avoid mixing component A with C (thinner) and after that mixing with component B, local Graco distributor, SC Romcrete Echipamente SRL, suggested a three-component automated installation. The implemented solution has a self-learning robot fed by a three-component paint line and works with a conveyer and cure oven. The Graco ProMix 3KS station works in low pressure with Graco Triton pumps for all components, even for cleaning solvent.

For a low volume of component B, a Corriolis 1/8 high-resolution flow meter was used. The result was one recipe for colour A:B at a ratio of 7:1 and one for (A+B):C at a ratio of 2:1. Using a conventional paint spray gun for high production and good atomisation, the flow increased to 150cc/min for the robot’s full speed. To avoid pulsation at the gun during pump change-over to component C, a fluid regulator of the mixed product is placed on the robot arms near the gun with a 5-metre hose.

When the viscosity of the mixed component viscosity was tested, the results were as expected: no errors occurred in the mixing process and the ratio had a tolerance lower than 5%.

MORE INFORMATION

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