Metal coating painting application without masking

Citation

(2000), "Metal coating painting application without masking", Industrial Robot, Vol. 27 No. 5. https://doi.org/10.1108/ir.2000.04927eaf.003

Metal coating painting application without masking

Metal coating painting application without masking

Keywords Painting, Coatings, Automotive industry

At the beginning of 1998, AXO-SCINTEX in France launched a new production line for the manufacturing of the Peugeot 206 tail lights.

Since 1985, this company has been producing lighting and signalling equipment for the automotive industry. More than 150 employees, working around the clock, are involved in this production. This spraying system developed by CERGI, France, is a new automated painting process. Thanks to the high precision of Stäubli robots (see Plate 3), painting consumption and consequently production costs, wastes and atmospheric pollution are reduced. The painting installation consists of spraying a partial metal coating of the parabolas on two plastic reflectors (right and left tail lights of the Peugeot 206 car).

Plate 3 High precision Stäubli robots

Before the introduction of robots, the manufacturing process was performed either by operators working in spray booths or by semi-automatic machines. In both cases, the positioning of masks to protect the areas not to be painted was necessary.

The suppression of these screens has been a technical challenge, and its success heavily decreased the lamps' production costs and highly improved quality consistency. In order to meet these requirements, an automated cell has been designed including the integration of a Stäubli RXPaint 90 robot.

Completely automatic, the cell produces 2,600 pairs of reflectors per day. There are no manual operations from the injection of the plastic parts by the press to the assembly station. The two right and left reflectors are loaded on a holder insuring correct positioning on one of the four carousel arms. After a quarter turn rotation, the parts move to the cleaning station by ionized air blowing. On completion, they turn again just in front of the dry air filter spray booth to be painted.

During the trajectory definition representing the outline of the parts to be processed, the distance between the nozzle and the part has been optimized to obtain a good cover quality and an acceptable uniformity of the overtaking area.

The homogeneity of the circular spot of the automatic spray gun, which represents the outline of the part to be painted, is obtained by acting on the robot command parameters (X,Y, Z coordinates, speed, etc.) and the same constant focal distance during the trajectories. The sprayed product's homogeneity is obtained thanks to the parameter control of the jet width and the possibilities of gun opening and closing in the robot control unit's user-program.

The robot's high precision and repeatability regulate the overspray area and guarantee finished product quality in terms of photometry.