The strength of press-glued and screw-glued wood-plywood joints

The effects of screw-gluing and gap-filling phenol resorcinol formaldehyde (GPRF) adhesive using different glue line thicknesses on the shear strength of wood-plywood joints were studied to determine the use of screw-gluing fastening (SG) method and GPRF adhesive. The specimens were manufactured using either SG method with GPRF adhesive and fine threaded drywall screws or press-gluing (PG) method with GPRF adhesive. The Analysis of Covariance (ANCOVA) was used for statistical analyses. The results showed that the strength among fastening methods was significantly affected by the glue line thickness, so the strength decreased as the glue line thickness increased. The SG fastening method was found as effective as the PG method and more effective when thick glue lines present. The method can be successfully used to bond wood to plywood for wooden panels i.e. stressed skin and sandwich panels.