European finishing technologies coming to IWF 2002; part 1: finishing materials, sanding and spray technologies. (Finishing Newsfront).
An Industry in Change
Environmentally benign finishing applications such as water-based and powder systems continue to grow, as the wood industry tries to comply with regulations and be a good corporate citizen.
At LIGNA, a clear trend toward UV curing and water-based lacquers was observable. Oil and/or wax-based systems also attracted significant interest. Today, most, if not all, surface finishing materials suppliers offer a wide range of environmentally friendly finishing solutions consisting of low-solvent or solvent-free systems. Most of these new materials and systems do indeed demand a somewhat higher price. However, such systems often lead to overall cost savings due to lower material requirements and/or lower operating costs.
Environmentally Friendlier Surface Coating Materials
Akzo Nobel displayed transparent and pigmented water-based lacquers containing 35 percent solids and less than 2-3 percent organic solvents.
Becker Acroma offered a new Wood-Wash-System in combination with water-based lacquers, which it said prevents yellowing of solid wood coated with transparent lacquers. Wood-Wash can be combined with spraying or roller-coating applications.
Bergolin presented two-component, water-based lacquers which it said have excellent chemical and mechanical properties. Another area of focus for the company are pigmented PUR lacquers with more than 55 percent solids.
Natural surface coating materials such as oils or waxes also attracted significant attention. In Europe, these products have a 10 percent market share and are likely to grow in significance.
3-H-Lacke offered a combination of Oil/Wax, which is cured under UV-light and requires only 0.03 - 0.05 ounce/square foot. Bergolin and Livos, Naturhaus Farben and Osmo also showed a large range of natural surface coating materials. Livos developed stains and coatings based on natural materials which are specifically designed for the coating of OSB and MDF surfaces.
Lintop showed a natural oil-based impregnation designed for industrial applications such as flooring. Using roller-coating equipment, followed by heating elements and brush polishing, products can be surface-finished in one cycle.
RadTech Europe Association presented systems for coating wood composites such as MDF with UV-powder. Powders contain no VOCs and the melt point is approximately 230F.
Sanding as Important as Ever
The old adage that only a well-sanded part will result in a well-finished product holds true today as much as it did in the past. In fact, quality requirements on sanding are ever increasing. The surface has to be evenly sanded and the fibers have to be cut and not pushed down. For industrial production, cross sanding nowadays is the norm.
Heesemann developed the sanding system MFA 6, which features the CSD pressure beam. Electromagnetically driven pressure elements locally adapt pressure to the part surface, achieving an even pressure distribution. Heesemann also showed improvements in CNC sanding of convex and concave surfaces.
Paul Ernst GmbH showed remote, internet-based diagnostics for its equipment. This system allows remote troubleshooting and support for maintenance and repair.
Cosma-Borstelfabrik presented the Cosma-Robot-Sander. This system allows automated sanding of finished case goods. It can be employed for wood as well as for lacquer sanding.
Instead of working with constant pressure against the part, the Fladder sanding system uses a rotating sanding tool. Using this principle, wood fibers are cut and not crushed. QuickWood works with thw tools from Fladder and offers brushes and entire machines. With these systems, curved parts can be sanded.
Cost Savings by Using Innovative Spray Technology
Most noticeable in spray technologies were the efforts to make color and coating changes simpler and to ease cleaning. Reducing color fog was another area of improvement by manufacturers.
Kremlin presented a lightweight AIRMIX gun, which it says reduces overspray by up to 80 percent and still guarantees excellent atomization. Also, the company replaced the piston compression in its Flowmax pumps with bellows, eliminating the need for maintenance of the cleaning liquid chamber. Kremlin also presented a new three-component-mixing installation, which allows automatic adjustment of the spray viscosity and fast color changes.
Kautzberger presented the new Mignon 3 spray gun. This gun has a light, solvent-resistant plastic handle and material supply can come through either the handle or a gravity cup.
Spray and lacquer systems from Waither featured a newly remodeled, environmentally sensitive spray mist -- color fog extraction system.
DETE spray and lacquer systems presented a new, ultra-light spray gun program, electrostatic handguns, the Vulkan continuous flow heater and EASY MIX two component mixing equipment. Vulkan is reportedly explosion proof, maintenance-free and allows the use of high-solids, low-VOC systems. The two-component equipment can be used for all lacquer systems and allows color changes in about three minutes.
Wagner entered the area of cold wax application. The paste-like wax is pumped to the gun using a piston pump. Wagner also displayed the Thermo-Spray-System, which allows the use of high-solids, low-VOC materials at an ambient temperature of about 149F. The system provides fast solvent evaporation and short drying times, and can be used for UV-oil-wax combinations and pure UV-spray-lacquers, Wagner says.
Rippert presented a spray system with special handling for wooden parts, combined with a water lacquer recycling system. This system reduces ancillary times and improves utilization of the spray booth.
Convincing Improvements for Automated Spraying Machines
Improvements for automated spraying machines included parts recognition, material recycling and system controls, with an eye toward reducing overspray and enabling faster color changes. Several systems featured improved air supply and were made easier to clean.
Venjakob presented a seven-axis spray robot for continuous feed using technology from robot manufacturer Straubi. A camera measures 3D parts at regular conveyor speed, and a computer calculates optimal paths and angles for the guns. In addition, the system has a fast gun changeover system and a clean-air spray cabin.
Cefla's EASY automatic spray machine with linear gun drive features a patented technology for lacquer recycling and a newly developed conveyor cleaning system.
Elmag-Superfici introduced the Twin-Spray surface spray machine. The Twin-Spray is equipped with two linear gun drives that run on precision guides driven by a servo motor. The company also introduced a wet doctor blade system to recycle lacquer overspray. By re-wetting the dried overspray on the conveyor belt with regular lacquer, all of the overspray can be recycled without employing additional solvent.
Giardina introduced Duplex, a one-operator machine for door manufacturers. Doors are fed and pass the equipment to the other side, where the topside is surface-finished. As the door passes through, it is flipped and returned into the machine, where it receives its final coating.
Urs Buehlmann is Assistant Professor and Extension Specialist, North Carolina State University, Department of Wood and Paper Science. Joerg Schleusener is Professor Emeritus, Swiss School of Engineering for the Wood Industry.
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|Publication:||Wood & Wood Products|
|Date:||Jul 1, 2002|
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