Investigating Moisture Gradient-Induced Warpage of Veneers

Flatness of wood composite panels, such as Laminated Veneer Lumber, is often difficult to control during the manufacturing process. Out-of-plane deformation, or warpage, of wood veneers caused by changes in moisture content affects the ability to press flat panels. To understand wood panel warpage, experimental methods are developed to create and measure moisture-induced deformation of wood veneers on five species of various thicknesses. Three moisture induction methods are investigated and evaluated to determine the increase in moisture content. Experiments are developed to produce moisture gradients of two concentrations in the veneers to examine the effect on warpage behavior. Additionally, the surface area of applied moisture and veneer thickness is also investigated.

Three-dimensional scanning technology is used to measure warpage of veneers. A procedure using a structured-light scanner is developed to analyze the surface curvatures to observe the effect of moisture-induced warpage. After moisture-induction treatment of the veneer, surface deformation data is measured using the scanner and the data is converted into a 3D solid body model that is used for curvature comb analysis.

The results show that curvature comb analysis can be used to analyze the geometry of moisture-induce warpage. The method can be used to analyze the effect of moisture gradient variables on warpage behavior including concentration, veneer thickness, and surface area. The experimental methods developed can be used by future researchers to validate theoretical warpage prediction models.