Summary
• LaserCoat is the result of a collaboration of eight academic, research and commercial organisations.
• It uses a layer of dry powder sprayed onto the surface of the substrate and selectively sintered.
• It holds the promise of allowing MDF which has been etched with a wood grain to be used with a translucent coating.
The versatile nature of MDF as a timber-based substrate within the furniture sector is well known.
However, in recent years the scope of use of this material has grown and it is now equally common to see it incorporated into the fabric of new build housing in the form of flooring, skirtings, architraves and, more recently, as joinery components.
The benefits of using MDF over solid wood in internal environments is that it offers a cheap alternative which responds to the variations in humidity expected in an internal situation far more uniformly, irrespective of the direction in which it is used.
However, for all these benefits, the main downside is that in its raw form it is a featureless material in need of finishing.
Where a uniform coating is required, this problem can usually be solved through the application of stoved or radiation-cured powder coatings, which yield a high gloss, resilient finish considered acceptable for most interior circumstances. If a grain pattern is required, current practices involve embedding paper or foil overlays printed with wood grain patterns into multiple layers of a resin on the surface of the material, to achieve a patina resembling natural wood. This process is both time-consuming and labour intensive, requiring additional handling operations and ultimately adding cost.
To develop a more cost-effective system of applying grain patterns to MDF, a three-year research project entitled LaserCoat was jointly conceived by TRADA and sister company FIRA (the Furniture Industry Research Association). The proposal won favour with the Technology Strategy Board and was subsequently part-financed by it, along with a partnership of eight academic, research and commercial organisations. The research programme is heavily reliant on the Warwick Manufacturing Group, which brings to the research its state-of-the-art knowledge and skills within the field of laser scanning and its application within the commercial sector.
In essence, the project developed a method that exploits the directional and focusing abilities of lasers and the thermosetting properties of stoving powders, where a layer of dry powder is sprayed onto the surface of the substrate and selectively sintered or consolidated into the required design using a high-speed scanning laser. Any un-sintered material can then be blown off with an air line and recovered.
Bespoke joinery application
The LaserCoat process can be used effectively for the sintering of complex designs such as logos, client names and so on, which has received interest from a number of joinery companies involved in bespoke work. Equally, it can be used to etch designs and patterns directly into low-grade substrates and can be painted using a conventional opaque coating, which allows the etched design to grin through. This process is seen as offering a remedy to an existing problem within the joinery industry, where exposed finger-joints can be masked using a relatively simple process. Laminated sections are increasingly being used on exposed surfaces as a means of maximising available output from existing wood stocks.
In its direct etching variation, the process also holds the promise of allowing MDF which has been etched with a wood grain to be used with a translucent coating in a very convincing manner. The thought of using a translucent coating on MDF as the only coating was, until now, considered as taboo and this technology could have the effect of extending its use within the building sector. This particular application will allow a substrate with greater thermal efficiency than solid wood to be used in the manufacture of door panels.
The project is now nearing completion and is still yielding golden eggs in terms of its versatility. Particularly promising is the finding that, by directly laser-sintering a powder coating that has already been thermally cured, it is possible to effect a subtle colour change under the path of the laser. The effect is a pleasing artificial colour rendition of a grain pattern, which can be used to add value to visible components around the house such as architraves and skirtings.
The research has yielded a patent, now filed, and is culminating in a series of dissemination activities aimed at establishing how the LaserCoat technology can be exploited within the commercial arena.
