Why is plywood a good material?

Plywood is one of the commonly used materials for furniture. It is a kind of man-made board. A group of veneers are usually glued together according to the direction of the wood grain of the adjacent layers. both sides of the core. It is a slab made of glued veneers crisscrossed in the direction of the wood grain, and pressed under the condition of heating or no heating. The number of layers is generally odd, and a few are even. The physical and mechanical properties in the vertical and horizontal directions are slightly different. Commonly used are three plywood, five plywood and so on. Plywood can improve the utilization rate of wood and is a main way to save wood. It can also be used for aircraft, ships, trains, automobiles, buildings and packing boxes.

In order to improve the anisotropic properties of natural wood as much as possible, so that the properties of plywood are uniform and the shape is stable, generally plywood must comply with two basic principles in structure: one is symmetry; the other is that adjacent layers of veneer fibers are perpendicular to each other. The principle of symmetry is that the veneers on both sides of the symmetrical center plane of the plywood should be symmetrical to each other regardless of the nature of the wood, the thickness of the veneer, the number of layers, the direction of the fibers, and the moisture content. In the same plywood, veneers of a single species and thickness can be used, or veneers of different species and thicknesses can be used; however, any two layers of veneer that are symmetrical to each other on both sides of the symmetrical center plane must be of the same species and thickness. The front and back panels are allowed to be different from the same tree species.

To make the structure of plywood meet the above two basic principles at the same time, its number of layers should be odd. Therefore, plywood is usually made of three layers, five layers, seven layers and other odd layers. The names of each layer of plywood are: the surface veneer is called the surface board, and the inner veneer is called the core board; the front surface board is called the front board, and the back surface board is called the back board; in the core board, the fiber direction is parallel to the surface board is called long core board or medium board. When forming a cavity deck slab, the front and back plates must be facing outwards.