LASER CUTTING AND JOINING OF WOODEN MATERIALS: HOW BOTH PROCESSES ARE DETERMINED BY THE HEAT AFFECTED ZONE

摘要

Wood and wood-derived materials are the most important materials with a world production of roughly 10~9 tons per year. However, because of the continuous development of the thermal and mechanical properties of wood materials towards high-tech applications, increasingly precise manufacturing processes have become attractive. In this contribution, the potential of laser cutting as well as laser welding of wooden materials is examined by quality-relevant material and process parameters. The heat-affected zones (HAZ) at laser-cut and laser-joint wooden surfaces are characterised measuring the temperature profile of the process within the cut kerf of particleboard and plywood. The HAZ of the CO_2 laser cut and Nd:YAG laser joint pine surface is characterized using infrared (IR) imaging and ultra violet (UV) microspectrophotometry. The thermally induced changes in wood composition (lignin) are analysed. The chemical and structural modifications seem to be most intense at the laser treated surface and decrease to levelling off at 35 (mu)m distance from the surface. Finally, economic aspects of laser cutting wood composites and a technological comparison to conventional wood cutting techniques is given.