Study on the Effect of Finger Joints on the Stiffness of Fibre-Managed E. nitens Sawn Boards

Abstract

Fibre-managed E. nitens has the potential to be used as a feedstock for engineered wood products. This resource, however, has a number of strength-reducing features that need to be removed, and the board needs to be re-joint to be useful in greater lengths for timber construction. A common jointing practice is finger jointing. The suitability of the finger jointing technique for this species is crucial to the mechanical properties of the final product. This study was conducted to explore the influence of finger jointing on the stiffness of sawn boards. A strict manufacturing process of docking and re-joining timber boards in the same location without removing strength-reducing features was conducted to compare the stiffness parameters before and after finger jointing with bending tests. A statistical analysis was conducted. The results showed that the frequency of finger joints along the board did not significantly impact the edgewise stiffness; however, the average flatwise stiffness of the samples with more finger joints was improved slightly. A 10% increase in the end pressure reduced the tip gap significantly but did not influence the stiffness. The finger joint efficiency was 0.824 for the edgewise stiffness of the samples and 1.034 for flatwise stiffness of the jointed sections.