Investigation on withdrawal resistance of various screws in face and edge of wood–plastic composite panel

Withdrawal resistances of screws driven into commercial wood–plastic composite (WPC) panels in both face and edge directions have been measured and the results have been compared with those of conventional medium density fiberboard (MDF) and particleboard. Three types of screws namely; sheet metal screw (gauge #4, 8, 10, 14), wood screw (gauge #8) and drywall screw (gauge #8) were used. The results have indicated that withdrawal resistances of screws in WPC panels in both directions increase as screw diameter, loading rate and penetration depth increase. Similar increases were observed when pilot holes diameter were increased close to the root diameter of the screws. Beyond this limit, increasing the pilot hole diameter up to the nominal diameter of the screws, significantly reduced withdrawal resistance. No significant differences were observed between different types of screw. Face and edge withdrawal resistances of screws in WPC panels were higher as compared with those of MDF and particleboard panels.