Research on Medium density fiberboard (MDF) behavior against screw axial withdrawal: Impact of density and operational variables

Abstract

Screw joint is a prevalent connection method in furniture, buildings, and structures, which plays an essential role in the integrity and durability of a wooden structure. Considering such benefits, the impact of core and face layers density, screw direction, pilot hole diameter, screw type, and water immersion on screw axial withdrawal resistance of medium density fiberboard (MDF) were investigated in this paper. The results showed that screw withdrawal resistance (SWR) of MDF panels in surface and edge directions were raised as density increased. The surface SWR was found to be higher than the corresponding ones in the edge direction. Besides, fine thread drywall displayed higher SWR than coarse thread drywall in both directions, due to more thread embedded. Results revealed that SWR was more affected by pilot hole diameter than panel density. Moreover, the best SWR was observed when the pilot hole was set close to the root diameter of the screw. The treatment of water soaking of MDF samples for 2 h negatively affected the SWR. Therefore, the edge SWR was more affected by water immersion. In addition, failure modes of screw withdrawal included sheet-shaped fracture of face layer along with protrusion of core fibers by pulling out the screw from surface and edge directions, respectively. This study suggests that a reliable connection can be made by selecting the proper screw and adjusting an accurate pilot hole even in a lighter product that is installed in humid conditions.