Automatic spray lines for fast and reliable product finishing

There are several companies that offer automatic finishing lines for different timber substrates. These lines provide a highly efficient way to finish both exterior and interior items such as kitchen cabinets, skirting boards, stair parts, cladding, and window and door components.

Most automatic lines will have in-line drying apparatuses to ensure rapid processing speeds. The drying methods include technologies such as hot jetted air, infrared irradiation, and UV-light. Different coating systems can provide different options to achieve the desired finish.

Makor is an example of a company that can provide a comprehensive setup that sprays and dries the items. In cooperation with Anker Stuy the two companies have been able to demonstrate that both interior and exterior woodcoating systems can be dried within minutes. Other companies such as Giardina Group, Barberan, and Cefla Finishing also provide coating and drying lines. This is of course not an exhaustive list of suppliers, other options are available.

Passing hot jetted air (at up to 40°C) across the substrate speeds up the evaporation of water from the coating, reducing the drying time from hours to minutes. At the beginning of the process, a flash-off zone is generally present to allow a good flow and levelling of the paint, while at the end of the process a cooldown section is used to allow problem-free handling of the coated items.

Special automatic spray lines

Giardina has created a spray head for horizontal spray lines that can also rotate 360 degrees.

To work well on this equipment, woodcoatings must have a few useful properties. First, the paint must remain at a stable viscosity to withstand the forces of the pumps. In addition, it is important that the primer has good filling capacity for MDF. For solid wood substrates, ingredients that help to significantly reduce bleeding from the tannins or resins that might migrate to the surface of the coating are incorporated.

Forced drying

Anker Stuy's Hydrolux Primer and Hydrolux Topcoat are very suitable products for forced drying. Both products have very rapid flow and levelling properties. This minimizes the time needed for flash-off, and therefore will save time on the production line. The prevention of coated surfaces blocking or sticking together is very important for automated lines. Most products are still thermoplastic and need a cool-off period before they can be stacked. At Anker Stuy, we developed a system that can be stacked very quickly after drying, which is a huge advantage when using our woodcoatings on high-speed lines. Another option is the drying chamber manufactured by Schuberts, known as the Schubox®. This uses a combination of catalytic infra-red and hot air movement supported with mirrors that reflect the infra-red waves back onto the timber substrates. These systems are produced in Sheffield, and our Hydrolux Woodcoatings have been tested in these cabins. As a result, you can achieve a dry finish within 19 minutes.

The items will be coated and stacked on racks which are then placed in the Schubox®. The Schubox® has easy entrance and exit points to allow a good flow through the apparatus.

The coating will be dried from inside out. The infra-red helps the coating to thoroughly dry (or cure), preventing formation of a layer of skin and making the paint hard, dry, and able to sand in a very short period of time. This high-speed curing assists with achieving rapid resistance to blocking. Another advantage is the development of early moisture resistance to the coating, allowing the joinery manufacturer to send products to site as quickly as possible, even in winter.

UV-curable coatings

In the picture below you can see the Barberan Spraying B8 machine. Barberan is a Spanish manufacturer of finishing equipment based in Barcelona. They predominantly supply their spraying machines in combination with UV-curing equipment. UV-curing can be done as the final step after evaporation of water in a waterborne UV coating. An alternative type of UV coating is the 100% solid UV-coating. In these products, no carrier solvent or water is present. The UV light is used to polymerize the coating from a liquid to a solid. With this type of UV coating, curing is achieved within seconds. Added advantages of this type of material are very low levels of fibre raising, very good filling on the profiled edges of MDF, and excellent protection against moisture ingress. Anker Stuy supplies multiple products for priming and finishing in both clear and opaque versions.

Cefla

Cefla is an Italian producer of finishing equipment that provide a wide range of spray booths, robots, and drying equipment. They can supply the entire finishing line to control the process and achieve a perfect surface result. They also have a comprehensive demonstration facility where they can do a trial application on any item that the client would like to treat with a given coating system.