And there it is, in black and white. When the Mercedes turns the corner in front of the Wörwag warehouse in Korntal-Münchingen, the very first thing we notice are the roof rails. Beate Beuttler is sitting ­behind the wheel. The 54-year-old chemical engineer is in charge of sales and technical customer service within the Paint Film Business Unit. She has been a member of the team since 2012, and has worked at Wörwag for 30 years. “Looks good, doesn’t it?” she asks as she steps out of the vehicle. She points toward the water deflector to the right, and to the windscreen at the left. The sharp contrast between the high-gloss black and the vehicle’s white body is intentional. Her colleague Holger Salzer comes to join us.

The rails are coated with transfer paint film. This method has been shown to be much more expedient, particularly when used for plastic add-on components, when compared to the classic wet coating method. The component is molded and coated in one single work step. An extruder laminates, as it is called in industry jargon, the transfer paint film onto the molten PVC of the workpiece. It also extrudes the requisite seals at the same time. Once this has been done, the component gains its final form.

No Overspray

There is no need to apply liquid base coat and clear coat, nor is drying in the furnace necessary. This allows time, along with a lot of energy, and therefore money, to be saved. And so too does the production of the film itself minimize the impact on the environment. The film is free of overspray – excess coating that remains in the ambient air instead of bonding to the substrate. This innovative coating technology has already scored Wörwag several environmental awards. Visually, a component with transfer coating is indistinguishable from a wet coated one. Carrier film and protective film are removed before or after the application respectively, with only the coating remaining on the workpiece.

Wörwag put the transfer coating into series production for the automotive industry, along with a decorative version for window manufacturers, in 2012. However, the product’s origins extend back to 2007. The warehouse on the industrial estate in Korntal-Münchingen is an almost ten-minute drive from the main plant in Zuffenhausen, and stands opposite the newly constructed building that the team will move into next year. This is also where the machines for cutting the rolls of paint film can be found, along with a recently installed cutting plotter – Salzer’s pride and joy. The high-tech unit is ushering in a new era for films. Helge Warta, who was recently promoted from the head of department to Vice President Business Unit Paint Films, and his team have big plans. The most visible sign of this: two new products for the automotive industry – a transfer base coat and a self-adhesive paint film. Both will be used by the industry to give components such as radiator grills or roofs a unique design.

Transfer coating from the roll

The adhesive version is undergoing a small endurance test today in the form of a logo as a finish. And it will be doing so in the car wash, the ‘automotive stylist’, so to speak. But instead of washing, cutting and styling, the washing plant will be plotting, bonding and washing. While on the way to the car wash, we are keen to find out more. “When it comes to the new products, there is far more variation in the delivery forms than for conventional coatings,” as Beuttler notes, her gaze focused on the glossy black logo on the engine hood.

Repair films used for windows provided the inspiration for an adhesive film for vehicle bodies. Just like these films, each also has an adhesive backing – and they also represent the best way to allow vehicles to be customized. Together with an automotive manufacturer, Wörwag has developed a number of metallic hues. In contrast to the transfer coating, the adhesive film not only comes supplied on rolls. “We can cut any shapes we like out of it to produce visual effects,” Salzer adds. The qualified painter and varnishing expert has been working at Wörwag since 1992, and joined the film team in 2011. Along with customer care, the 47-year-old is now primarily responsible for looking after the process technology.

Wörwag adhesive film performs best

The company car rolls into the car wash. “Speaking of process technology,” as Beuttler segues into her next point, “the most important innovation is that we also supply the application equipment used for the products.” To do this, the coating factory has joined forces with a mechanical engineering company. This brings benefits for the customers, who then have a machine designed to cater to the dimensions of their workpieces. This allows any motif they like to be plotted for each and every component. Only the workholder has to be adapted when coating a different workpiece on the same machine.

In order to ensure that users of the paint film have access to optimal support and information about the product and process, Wörwag has now changed the department’s status to that of a strategic business unit. This gives it more autonomy, flexibility and clout, allowing it to push its products through to market maturity more quickly. Given the rapid transformation that the technical and economic environment is undergoing, this will be a key to success. Because electric vehicles in particular need to be light in weight, the significance of plastics in automotive construction is increasing. This also means the demand for application-friendly and environmentally sound coating technology is growing.

The cellular rubber rollers are meanwhile clattering over the vehicle body in the car wash. They make no impression on the logo that forms the finish. And why would they? As is the case with classic coatings, Wörwag also tests the resistance of the films to moisture and dryness, heat and cold, as well as to ­aggressive chemicals. The air dryer starts bellowing. The logo stays in place. “An Asian automotive group has tested the adhesive films made by several manufacturers. Ours performed the best, especially in terms of ­resistance and adhesion,” Beuttler is pleased to report, running her hand over the engine hood, whose gleam reflects the delight written all over her face.

Individually cut to size

Which geometry is needed? Wörwag can deliver its newly developed self-adhesive paint film in many different colors and shapes. The cutting plotter makes it possible: It cuts contours on an area from 1.2 to 1.6 meters in size.

Holger Salzer received the finish logo used in this story as a vector file. After a quick check on the computer, he sends the graphics to the plotter, where he is still able to make modifications . The film to be cut is held in place by suction to ensure it is exactly positioned. The plotter then starts up . It doesn’t even take 30 seconds to cut the logo free. A blade is used for cutting. “It functions more precisely than a laser,” as Salzer says. Given that the coatings measure from 10 to 500 micrometers in thickness, precision is particularly important . Salzer inspects the quality at the vacuum table while he weeds the letters – meaning he removes the off-cuts. The engine hood is now ready to be laminated .

By the way: As good as the adhesion of the film is, it can also be removed without leaving any residue, when necessary. Beuttler and Salzer also put this to the test for us.

(This article first appeared in the Wörwag customer magazine finish in 2019.)