Comparison between Some Factors Affecting Screw Withdrawal Resistance from Different Wood-composite Panels

Effects of screw type, screw diameter, and drive direction (perpendicular to the face and edge of specimens), as well as wood-composite panel type, on the withdrawal resistance in bagasse-fiber particleboard (BPB), medium density fiber board (MDF), and plywood were investigated in the present study. Two sizes of fine-thread drywall screw (sizes 8 and 10), and two sizes of sheet-metal screw (sizes 8 and 10), were chosen. All screws were 50 mm in length. The results showed that an increase in the screw size would result in higher withdrawal resistance in both screw types. Furthermore, plywood showed higher withdrawal resistance in comparison to the other two wood-composites. Due to higher integrity in the wood-composite, withdrawal resistance perpendicular to the face of the composites was higher in comparison to the edge direction. Longer thread in sheet-metal screws caused better involvement with the composites and therefore more connecting surface; consequently, stronger involvement with it, resulting in higher withdrawal resistance of sheet-metal screws.