Mechanical characteristics of wood biscuit joints

Abstract

Wood biscuit joints are commonly used to join particleboard and medium density fibreboard (MDF) panels. This paper describes the mechanical characteristics of biscuit joints. Specifically, the moment of resistance and bending stiffness of biscuit joints are evaluated. Centre to centre spacing between the biscuit holes, edge distances between the centres and the corresponding edge of board, the type of loading as compression and tension loads, the type of composite materials, and glue effects are taken into consideration. The experimental results indicate that gluing of the face and butt members significantly affect joint strength. The maximum bending moment for particleboard joints was 5.74 Nm under tension and 6.0 Nm under compression. These values were 5.39 Nm and 4.69 Nm, respectively for MDF joints. In addition, the experimental results also indicate that biscuit joints in particleboard panels are stronger than those in MDF panels. The former tensile strength was 7.4% and the compression strength was 29.9% higher than the latter. However, the biscuit joints in MDF panels were found to be stiffer than those in particleboard panels by an average of 11%. The on-centre spacing between biscuits had insignificant effects on the joint tensile and compressive strengths of the joints. This discovery is useful for the manufacturing industries where fewer biscuits can be used and time and cost can be saved. Finally, the experimental results suggest that the bending strength of glued and unglued joints is inversely related to the spacing between the centres of the biscuit holes and the edge distance between the holes and the board edge.