Matte finish for 3D printed turn signal light cover

For the wet paint coating of a special edition of automotive turn signal covers made of 3D-printed plastic parts, a surface specialist relies on special handling in the painting process.

Automotive designers also have an eye for the smallest details when it comes to giving their vehicles that special something. In the case of the "Untold Edition" of the MINI Clubman, for example, these are the so-called side scuttles - accentuating partial covers for the side turn signal lights on the front fenders. The surface specialists at Benseler give these 3D-printed plastic elements their colorful shape.

Measuring 160 mm x 40 mm, they are slightly longer than a cigarette pack and initially not very effective in their raw state: the caps for the side turn signal lights of the MINI Clubman in the "Untold Edition". However, this changes with the processing by the surface specialists at Benseler, who prepare these 3D-printed plastic components ready for assembly at the Bogen site for the client BMW Group according to its design specifications.

Due to the large number of parts required, trim elements used in the interior and exterior of model series are normally produced using plastic injection molding. However, the special edition of the MINI Clubman for which the side scuttles are intended is restricted to an exclusively limited number of vehicles. For this reason, the few thousand covers with their typical hatching are produced at the BMW Group's 3D printing center in Munich.

The blanks are made of polyamide granulate, which has been fused layer by layer by the lasers of the 3D printers to form the specified diamond shape. These plastic blanks, with their rough surface structure due to the manufacturing process, are first sanded at Benseler - the outer edges by machine, the filigree lamellae of the hatching manually, so that the structure is preserved. Mounted on a painting suspension, designed by the surface specialists to fit these special covers precisely, the components then enter the actual painting process. This first involves a primer coat to level out any remaining unevenness. This is followed by the coloring paint layer with the "Sage Green" color variant, which is finally coated with clear lacquer - a matt finish for the desired design effect.

To fix the respective orders, the components pass through the baking oven after each shift. The handling of the oven is the real challenge, because on the one hand the heat-sensitive plastic parts must not get out of shape. On the other hand, the paint application must dry in such a way that no paint noses or similar form, which in the worst case would make assembly impossible. However, Benseler has mastered a wide range of wet paint processes for over 30 years - for metals, but also for plastics. That is why the complex requirements of the turn signal light covers are no obstacle for the experts to achieve high quality and lasting value of the surface even for these 3D-printed plastic parts. The fact that they succeed in doing so is demonstrated by the follow-up order, which includes another batch of the Side Scuttles in the "Jet Black" finish. (OM-02/23)