The Effect of Veneers Roughness on Bonding and Some Mechanical Properties of Plywood

Bonding technology is one of the keytechnologies for producing wood-based materials.Surface quality of solid wood products is one of themost important properties influencing furthermanufacturing processes such as finishing orstrength of adhesive joint. The aim of this study wasto determine the influence of sanding with differentgrit sizes on bonding strength and some mechanicalproperties of poplar and beech plywood. For thisreason, 2mm thick rotary cut veneers obtained fromfreshly cut (not treated) poplar (Populus deltoides I-77/51) and beech (Fagus orientalis) logs were usedas material. The surfaces of some veneers weresanded with 80 and 180 grit size. Three-layerplywoodwere produced from sanded and nonsandedveneers using phenol formaldehyde glueresins to evaluate the effects of sanding somemechanical properties of plywood. Rz roughnessparameter was measured to evaluate surfaceroughness of veneer according to DIN 4768.Bonding and bending strength values of plywoodmanufactured from sanded and non-sanded veneersvaried depending on wood species and grit size.Bonding strength values of plywood increased withdecreasing surface roughness values of veneersboth of two wood species.