Novel Analytical Method to Determine Factors Causing Unwanted Sticking of Glued Wood Particles onto Machinery Parts

“Sticking” of glued particles onto machine parts (blender, conveyor, forming station) during wood panel production increasingly occurs when applying low-emission aminoplastic adhesives. Therefore, a new and reproducible method to investigate sticking effects was developed. With this setup, both drying out of the adhesive and the tendency of particles to adhere onto machinery components can be described. The method consists of a rotating cylinder made out of different materials and of diverse surface roughness in order to simulate machine parts, which runs over a wood surface where resin is applied. The wood surface represents the wood particles. The temperature of the wood surface and the ambient air as well as the relative humidity can be controlled. Before starting the experiment, a defined amount of adhesive is applied onto the wood surface and with this a “glue line” is built up. Drying out of the adhesive causes an increase of the rolling resistance up to a peak value. Afterward, an abrupt or gradual decrease of the rolling resistance is observed. This rolling resistance is accurately measured and recorded. Using the approach described above, influences of different materials, climate conditions, surface temperature and roughness, as well as adhesive properties can be observed. The initial results provide strong evidence that climate conditions of the ambient air as well as material and surface properties of machine parts show a significant contribution to the phenomenon.