The variety of options for painting wood and wood materials is constantly expanding. The demands are also stricter than ever: in addition to good quality and economy, material efficiency, low energy consumption, flexibility and sustainability are essential.
by Doris Schulz*
Whether it's furniture and floor coverings, office and store shelving, or windows and doors, the ever-changing variety of colors is a challenge for companies with on-site painting processes and small series production workshops.
On the other hand, effective protection of the coating against mechanical, chemical and physical influences such as scratches, ultraviolet radiation and cleaning products is also required. Quality, efficiency, flexibility and environmental compatibility are, of course, the highest priorities in painting wood and wood materials.
Effective pretreatment
Regardless of whether solvent-based, water-based or ultraviolet paints are used, a prerequisite for a high-quality paint is a perfectly sanded surface. New industrial developments are allowing the optimization of sanding processes. Among these is, for example, the technique of sanding diagonally. With this process the sanding unit rotates slightly obliquely with respect to the conveyor belt. In this way better results are obtained, especially in the range of products of higher quality.
And this is due to the fact that the quality problems caused by the inevitable minor damage caused to broadband sanders belts for example, grain chipping, irregular wear and jamming are no longer visible in the sanding pattern. Thanks to the diagonal arrangement of the sanding belt, the defects in the sanding band are increasingly shifted to one side with each revolution and blurred in the piece.
Another advancement that is enabling more efficient sanding processes is a module for automated sanding of the edges on both sides, which can be integrated into automatic processing lines. In many cases, this step of the process is still done manually. Especially in the manufacture of doors, this module is reducing costs in working procedures.
Savings in the application of paint
As for manual paint application booths and automated painting systems, new developments are concentrating on material efficiency, quality and flexibility. On the one hand, the new manual painting systems are distinguished by minimal weight and simple and safe handling. Both characteristics make the painter's work, which is usually long and arduous, much less stressful.
On the other hand, the application of paint without vibration is contributing to the obtaining of better results. This benefit is achieved by means of an innovative magnetic seal that avoids the excessive discharges of paint associated with conventional pumps and that take place during the reversal of displacements. As a result, irregularities and shadows in the surface finish are significantly reduced, or completely eliminated.
In the case of aerosol application guns, the adjustment of the spray tip, which can be easily adapted to the requirements specified for the object to be painted, together with the corresponding ventilation windows, guarantee adequate efficiency in the application and minimize excess spraying. Together, energy consumption can be reduced by up to 25% using this method.
Putting an automated painting system into operation allows a solution that can be used in different production environments: from manual work, mainly with small batches or for series suppliers with large quantities, to industrial production with high performance speeds. The spray painting machine can be used with both solvent-based and water-based paints.
In response to the increasing processing of tiles in the window manufacturing sector, paint system manufacturers are offering separate component coating lines. With these machines the entire coating process is carried out in the independent parts, from impregnation to finishing layer. Unlike flow and aerosol coating of components that have already been glued, this method has the advantage of achieving a uniform application of paint with a layer of a constant thickness. In addition, it is usually not necessary to apply an additional layer on the corner joints.
There is an automated 2D programming system on the market for the robotic application of paint on doors and windows that must be painted in different ways. This alternative consists of a detection system whose luminous tape scans the window with beams of infrared light. The shaded pattern resulting from the data obtained is read in the 2D controller, which generates a suitable painting program.
Paint solutions for all cases
Solvent-based paints are still widely used to coat wood and wood materials. There are paints with a very high or very high solids content, whose objective is a greater reduction of the emissions generated by these paints. Its use usually requires only minimal adjustments to existing paint systems.
A scratch-proof, high-gloss, high-thickness, nanotechnology-based transparent coating has been developed for glossy finishes. The so-called refusion technology is being used for the first time in wood cladding applications using this paint. This technology gives the painted surface a "self-healing" effect.
Paint manufacturers are also working on optimizing water-based systems for painting wood and wood materials. Among these systems is a new generation of water-based paints that can be used in many applications in the commercial woodworking sector, as well as in a wide variety of industrial applications in the interior construction sector, and in furniture, such as tables and chairs.
The new materials allow the development of formulas that make these water-based paints particularly durable and give them high-strength characteristics. Unlike other water-based paints, these are also distinguished because they can be sanded more quickly. They can be applied by the usual aerosol and pouring processes. They can be applied to vertical surfaces in aerosol. Painted wood provides a pleasant feeling. The hardened paint film complies with the EN 71/3 standard, and is resistant to creams and water.
A new dyeing system allows commercial users to quickly and easily produce their own dyes with different effects. This modular solution consists of four basic color dyes, three basic colorless dyes and nine color concentrates.
New advances in the area of powder enamels further expand the range of coatings for wood, medium density fibre (MDF) panels and other heat-sensitive materials. These painting systems, which to some extent can be adapted to applications for coating 3D objects, also allow the production of finishes on very bright surfaces.
Box
International trade fair for industrial coating technology
PaintExpo covers the entire process of coating technologies and provides a complete overview of the latest developments. The offerings cover the entire spectrum of industrial coating technology: application systems and technology, drying, automation and handling systems, paints, pickling, cleaning and pretreatment, environmental technology, aeration, pneumatic pumps, exhaust gases and wastewater treatment, waste, measurement and verification technology, quality assurance, accessories, coating in small series production workshops, services, training and R&D.
PaintExpo will be held at the exhibition center in Karlsruhe, Germany, from April 8 to 11, 2014. Prior to this event, FairFair GmbH will promote the second version of PaintExpo Eurasia in Istanbul, Turkey, from 12 to 14 September 2013, in collaboration with Artkim Fuarcilik, a Turkish specialist in paint and chemical trade fairs.
* Doris Schulz is a specialist in the field of surface treatment, has her own public relations consulting firm that currently leads the PaintExpo 2013 fair in Istanbul, Turkey, which will take place from September 12 to 14 and PaintExpo 2014 that will take place from April 8 to 11 in Messe Karlsruhe, Germany. [email protected]
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