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Micropainting by robots
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Published April 9, 2007

Can an automated painting process replace the skilled hand-painters in China? A pilot project aimed at automating the paint process from a designers drawing of a toy to a finished product ready for the market in one step. Reducing costs and time-to-market were the primary goals for the producers of the chocolate egg Kinder sending up to 23 million pieces to China each year for hand-painting.

Small toy figures are often designed as trend-objects reflecting the latest innovations: Disney, Harry Potter or Star Wars figures. A 6 month painting process made it difficult for manufacturers to deliver a new collection in time with the market, and the long sea-transport added to the cost of each figure. The main goal of the project was to integrate the painting process in the production process with practically no time-overhead, and to do this on the site of production.

The toy designer provided a CAD model to the painting system consisting of a robot arm and an ink-jet paint system with a special adhesive ink. Based on the colour information of up to 6 different colours embedded in the CAD model, a number of points was identified on the toy figure defining position, colour and size. This process is not unlike what takes place inside an ordinary colour ink-jet printer where a row of nozzles sends out short spurts of ink while the paper advances. When a jet of ink hits the paper, a tiny dot is formed. Together, a large number of such dots make up a picture.

The one-step painting process took the position of each point on the figure and automatically generated a motion trajectory for the robot arm holding the figure. This motion trajectory was synchronized in time with the ink-jet control system to ensure that the correct amount of paint was exerted onto the toy figure when the desired point of the figure was placed in front of the paint nozzle.

Although potentially reducing the costs and time-to-market for toy figures, the project was met with some animosity amongst collectors of Kinder figures fearing that the figures would loose some of their much cherished diversity.

Contact person at SINTEF Applied Cybernetics: Geir Mathisen