Plywood is a board that is made by rotary cutting logs into large veneer boards along the direction of annual rings, and after drying and gluing, they are assembled and glued together according to the principle that the wood grain direction of adjacent veneer layers is perpendicular to each other. The number of veneer layers is odd, generally three to thirteen layers, and the common ones are three-plywood, five-plywood, nine-plywood, and thirteen-plywood (commonly known as three-centimeter board, five-centimeter board, nine-centimeter board, and thirteen-centimeter board in the market). The outermost front veneer is called the panel, the reverse is called the back panel, and the inner layer is called the core. Plywood can improve the utilization rate of wood and is a major way to save wood.
Plywood is one of the commonly used materials for construction and furniture, one of the three major wood-based panels, and can also be used for aircraft, ships, trains, automobiles, construction and packaging boxes. A group of veneers is usually glued perpendicular to each other in the direction of the wood grain of adjacent layers, and the surface and inner layers are usually symmetrically arranged on both sides of the central layer or core. It is made of a slab made of glued veneer criss-crossed in the direction of the wood grain, pressed under heated or unheated conditions. The number of layers is generally odd, and a few have even numbers. There is little difference in physical and mechanical properties in the vertical and horizontal directions.
The usual length and width specifications are: 1220×2440mm, and the thickness specifications are generally: 3, 5, 9, 12, 15, 18mm, etc. The main tree species are: camphor, willow, poplar, eucalyptus, etc.
The first type of plywood is weather-resistant and boiling water resistant plywood, which has the advantages of durability, high temperature resistance and steam treatment;
The second type of plywood is water-resistant plywood, which can be impregnated in cold water and hot water for a short time;
The third type of plywood is moisture-resistant plywood, which can be impregnated in cold water for a short time, and is suitable for indoor use at room temperature. for furniture and general construction purposes;
The four types of plywood are not moisture-resistant plywood, which are used in indoor normal conditions, and the materials used for general purpose plywood are beech, basswood, ash, birch, elm, poplar, etc.
Building plywood is mainly used in outdoor conditions, such as building exterior decoration and concrete formwork, and is mainly used in decoration projects for ceilings, wall skirts, floor linings, cabinets, tables and other furniture
