The effect of lath shear direction on some technological properties of edge-glued panel produced from hardwoods

This study is to investigate the effect of cutting direction on some physical and mechanical properties of edge-glued panel produced by using hardwoods. Edge-glued panel boards are provided from a lumber factory located in Düzce. In the production of edge-glued panels, drafts are used to end-to-end finger jointing, while laths are used side-by-side flat joint method. By using the test samples, to determine physical properties; moisture and density tests, mechanical properties; parallel and vertical bending strength, modulus of elasticity, tensile strength and impact bending strength resistance and Brinell hardness values were determined. Its observed that one of the physical properties of the edge-glued panels, equilibrium moisture content vary between 9.68-10.28 %. The air-dried density values of these panels were obtained 0,695 g/cm3 for beech, 0,682 g/cm3 for oak, 0,666 g/cm3 for iroko, and 0,645 g/cm3 for sapelli. It was determined that there were significant differences between the tree species in terms of the mechanical properties of produced edge-glued panels. The highest strength values were obtained from beech edge-glued panel. However, the oak panels have showed higher modulus of elasticity than the other plates (1080 N/mm2). Mechanical properties of iroko and sapelli edge-glued panels were found close to each other. The lowest strength values were observed in sapelli panels. There was no significant difference among the Brinell hardness value perpendicular to the fibers of the edge-glued panels produced in the cutting direction, the dynamic bending strength parallel to the fibers and the modulus of elasticity in the bending direction parallel to the fibers. Generally, the highest mechanical properties were obtained for edge-glued panels produced in the radial cutting direction. However, the average tensile strength values in parallel to the fibers of the standard and tangent panels were found to be higher than the radial panels. Except for the impact bending (shock) strength parallel to the fibers, the lowest values were found in the tangential panels. In term of wood type and cutting direction, the highest values were observed in beech-tangent edge-glued panels for bending strength and tensile strength and modulus of elasticity in parallel to the fibers.