Several years ago one of the internationally leading specialists for plastic surface finishing, GfO AG Gesellschaft für Oberflächentechnik AG, Germany, was faced with the challenge of implementing the use of a new inkjet method for which a new plant for painting plastic display windows was to be specifically built.

Application 
Given the high degrees of automation demanded today, inline processes need to be implemented for applying transparent, scratch-resistant coatings on to plastic components such as display front panels. GfO”s standard then current manual method of pretreating front panels with alcohol and cloths was to be replaced by a new, qualitatively higher-grade pretreatment technique which guaranteed consistency. To ensure long-lasting adhesion of paint while creating a flawless surface would simply not be possible without subjecting the plastic components to an additional micro-fine cleaning and activation process step before painting. The new overall painting process in the clean-room would now be handled in a fully automated, environmentally friendly and more expedited manner. After having considered a number of different options, GfO decided in favor of the Openair-Plasma^® technology. After the successful implementation, hundreds of thousands of plastic panels for the automotive industry are now being pretreated with plasma and coated with scratch-resistant paint in a single year, not to mention the large quantities of display windows intended for other industrial sectors such as the Medical, White Goods, Aviation and Electronics industries. 

In this application an Openair-Plasma^® rotary nozzle of type 1004 that was specifically designed for gentle treatment for the complete surface is being controlled by a linear robot. The plastic panels, after having undergone micro-fine cleaning and strong activation, receive their scratch-resistant coating in the paint shop immediately following plasma treatment. Thanks to the high surface energy generated through atmospheric plasma, the paint is transformed into a homogeneous film.

Benefits Openair-Plasma^® offers the user the following values:     

• Improvement of the paint adhesion    
• Homogeneous paint application with a flawless paint appearance    
• Environmentally friendly pretreatment without the use of wet chemicals    
• Inline pretreatment in automated process operations    
• Safety and consistency of the technological application in the production process    
• Increased throughput speed    
• Extended maintenance intervals    
• Higher cost-effectiveness

Displays