In order to try to improve plywood to improve the anisotropic properties of natural wood, plywood is characterized by a uniform, stable shape. Plywood generally follows two basic principles in structure: First, symmetry; Second, adjacent layer veneer fibers Vertical perpendicular to each other. The principle is that plywood is needed on both sides of the plane of symmetry of the plywood, regardless of the nature of the wood. The thickness, number of layers, direction of the fibers, and moisture content of the plywood should all be symmetrical. In the same plywood, a single type and thickness of veneers may be used, or veneers of different types and thicknesses may be used; however, any two symmetrical symmetrical veneers on both sides of a symmetrical central plane should be of the same type and thickness. Different tree species.
In order to make the structure of plywood comply with the above two basic principles at the same time, the number of layers should be an odd number, so the plywood is usually composed of three layers, five layers, seven layers and the like. Numbered plywood is:. The surface finish is called the surface board, and the interior finish is called the core board; the front board is called the panel, and the back panel is called the back board; in the core board, the fiber direction is parallel to the board and it is called the long board or mid board. When forming the platen, the face plate and the back plate must face outward.