Automation: Watch Your Costs Fall and Your Quality Rise

Paint robots, once considered a luxury, have seen their prices drop significantly and have quickly become the norm in industrial topcoat application. These systems deliver consistent topcoats on every component. Better consistency also means less wasted material, and automated systems have been shown to reduce material consumption by up to 30%.

Automatic Application of Adhesives

An example of a company that has made the transition to automation is Peak Contracts Ltd., based in Derby, England. The company provides general industrial electrical and mechanical engineering solutions ranging from modifications to existing facilities and processes to the full design and construction of new facilities. Among its areas of expertise and services are topcoat application systems, air handling systems and electrical control systems, along with project and site management, service and maintenance. Among the firms for which it has completed projects are major automotive manufacturers. For one of its customers, Peak Contracts was planning to supply a dual-robot spray system for two-component water-based sprayable adhesives for automotive interior trim components. The challenge here was to set up and pre-program two robots with three different pre-mixed two-component water-based adhesives and spray onto multiple products on the same production line. Peak Contracts designed the robotic system with its own PLC/graphical user interface and integrated Graco fluid supply and spray equipment. They used three AirPro automatic spray guns, three pressurised feed containers and three air-operated fluid regulators supplied by local Graco distributor Fluid Technologies Ltd. The system was fully assembled, tested offline and then installed on the production line by the Peak Contracts team. Operation of the dual-robot spray system was facilitated through the use of Graco stainless steel pressure tanks relying on weight sensors to provide level indication on the graphical user interface. Air-operated fluid regulators allow flow rates to be adjusted to the spray gun during the spray programme. They also open fully during cleaning. AirPro spray guns provide excellent atomisation and are easy to clean after use. Quick-disconnect gun mounting makes it easier to maintain spray guns during production. With the installation of the new robotic application system, production throughput has increased and through the automation of the manual process, adhesive usage has been reduced.

Soft-Touch Paint Automation

Automation has proven to be an emerging trend for soft-touch coating as well, thanks to its ability to create a high-quality appearance with low-cost materials. According to a recent study, the global soft-touch polyurethane coating market is expected to expand at an annual growth rate of 7.2% between 2015 and 2025. Behind this rise lies the ability of soft-touch materials to transform an unwanted plastic feel into a comfortable rubber, leather or velvet-like sensation. It transforms a hard, cold plastic component into a warm, inviting object that says "touch me". Beyond that, it exhibits high scratch and wear resistance and protects the plastic from chemicals that could cause deterioration or unsightly yellowing when exposed to a harsh environment. With its robust surface and positive tactile effects, it still exhibits a slight sheen and low reflectivity. This allows manufacturers to take a relatively inexpensive material like plastic and apply a coating to create a premium luxury product. The ability to create a high-quality appearance with lower-cost materials is driving many industries to use soft-touch coatings. The automotive industry, which uses soft-touch to coat interior components, holds a significant share of the market: steering wheels, dashboards, door handles and trim, push buttons, airbag panels and armrests. The aerospace industry also benefits from similar applications on the interior panels of cockpits. Soft-touch coatings are also commonly found in consumer goods in the kitchen, such as coffee makers, ovens, refrigerators and even handles on pots and pans. Furthermore, the appearance, feel and protective qualities of soft-touch coating have become the norm for laptops, tablets, remote controls and mobile phone cases. Here too they provide a more pleasant feel that protects the product from impacts and prevents it from sliding off a table. The scope of soft-touch coating has extended beyond consumer durables to the consumer packaging industry, where it is applied to everything from cosmetic bottles to food boxes. This coating provides potential consumers with a high-quality and even luxury appearance. For this reason, many manufacturing companies are turning to soft-touch use to differentiate their products from competitors.

Soft-Touch Application

The application process is essentially the same, but several points need to be considered due to small differences in the composition of the material, which can increase quality and greatly improve overall production; this means fewer headaches for those applying the coating and higher satisfaction for end users. Much of the application equipment required for soft-touch materials is similar to that used for other topcoats and coatings. Spray guns, pumps and mixers can easily be converted to soft-touch applications. However, due to the heavy consistency of this material, it tends to sag when not sprayed with the correct parameters for the desired surface coating. Before starting production with this new material, several tests should be carried out to ensure that the process parameters are correct. Controlling parameters such as flow rate, spray gun air and pressure during the production process will also ensure that the desired homogeneity is achieved and maintained. Keep in mind that obtaining a consistent spray pattern near the end of the bucket's life will be more difficult. The need for the correct mix ratio and the effect of bucket life can raise the question of mixing strategy. After soft-touch resin and catalyst are mixed, there is a specific time window until the spray operation is completed. Therefore, when applying soft-touch coating, the biggest question to be answered is "What is the most effective and efficient way to mix?"

Electronic Mixing and Metering

One option is to manually mix the resin and catalyst. It can be cheaper because it requires minimal technology, but it has many limitations. The most important of these are excess waste, ratio accuracy problems, batch-to-batch inconsistency and resulting quality defects. Electronic ratio controllers offer an automatic way to mix two-component materials on demand. The equipment uses counters, metering valves and electronic closed-loop controls to mix materials in the correct ratio while the product is being sprayed. Only what is needed at that moment is mixed, which significantly reduces the material waste experienced by mixing batches. Additionally, colours can be easily changed on the fly, flow rates can be controlled and alarms can be used for quality control if problems arise. Electronic 2K systems can demonstrate that they pay for themselves over time through waste and time savings.   Marc Gijbels Product Marketing Manager IPD Graco