Board technique

Thanks to a new measuring technique, manufacturers of Oriented Strand Boards (OSBs) will soon be able to monitor the distribution of the glue used in their manufacture, helping them to save costs and optimise their production processes.

OSBs are an engineered wood product formed by layering strands (flakes) of wood in specific orientations.

They are manufactured in wide mats from cross-oriented layers of thin, rectangular wooden strips that are then compressed and bonded together with resin adhesives.

To optimise the production process, manufacturers of OSBs always have to make sure the mixture is right. If they use too little resin, or if the resin is not distributed properly on the strands, the resulting boards are not firm enough.

But the resin is expensive and accounts for roughly one-third of the production costs, so using too much resin is a waste of money.
 
Now, researchers at the Fraunhofer Institute for Wood Research and their colleagues at the Reutlingen Research Institute are helping manufacturers to distribute the resin as efficiently as possible.

Burkhard Plinke, project manager, said: ’We use special optics to measure how well the resin is distributed.’

At present, manufacturers use expensive dyes for this. They add the dyes to the glue and then check how it spreads inside the board.

However, this method can only be used on random samples, whereas the new technique will enable continuous measurements during production.

In the new Fraunhofer system, a line spectrograph – a camera with integrated optics – scans the surface of the mat before it enters the press, recording a near-infrared image of a narrow section across the entire width of the forming line.

Plinke said: ’A computer stores the data and analyses it online before the mat is transported into the press. The data indicate where the strands are glued and where they are not.’

Thanks to the new technique, OSB manufacturers will soon be able to monitor the distribution of the glue online and quickly detect any unevenness.