Take you to know plywood

2023-02-15

Take you to know plywood

Plywood（Leader plywood） is a three-layer or multi-layer board material made of wood segments peeled into veneer or wood planing into veneer, and then glued with adhesive. It is usually made of odd layers of veneer, and the fiber directions of adjacent layers of veneer are perpendicular to each other.
Plywood is one of the commonly used materials for furniture, one of the three major wood-based panels, and can also be used as functional materials for aircraft, ships, trains, automobiles, buildings and packaging boxes. A group of veneers is usually assembled and glued perpendicular to each other in the direction of the wood grain of the adjacent layers. Generally, the surface and inner layers are symmetrically arranged on both sides of the central layer or the core. The slab, which is made of glued veneer in a crisscross manner in the direction of wood grain, is pressed under the condition of heating or not heating. The number of layers is generally odd, and a few are even. The difference of physical and mechanical properties in vertical and horizontal directions is small. Commonly used plywood types include plywood, plywood, etc. Plywood can improve the utilization rate of wood and is a main way to save wood.

The usual length and width specifications are: 1220 × 2440 mm, and the thickness specifications are generally 3, 5, 9, 12, 15, 18 mm, etc. Main tree species include beech, camphor, willow, poplar, eucalyptus, etc. In order to improve the anisotropic properties of natural wood as much as possible, and make the properties of plywood uniform and stable in shape, generally, the structure of plywood should comply with two basic principles: first, symmetry; The second is that the adjacent layers of veneer fibers are perpendicular to each other. The symmetry principle requires that the veneers on both sides of the symmetrical central plane of the plywood, regardless of wood properties, veneer thickness, layer number, fiber direction, moisture content, etc., should be symmetrical with each other. In the same plywood, veneer of single tree species and thickness can be used, and veneer of different tree species and thickness can also be used; However, any two layers of symmetrical veneer on both sides of the symmetrical central plane shall have the same thickness. The top and back boards are allowed to be different from the same tree species.
In order to make the structure of plywood comply with the above two basic principles at the same time, its number of layers should be odd. Therefore, plywood is usually made into three, five, seven and other odd layers. The name of each layer of plywood is: the veneer on the surface layer is called the surface board, and the veneer on the inner layer is called the core board; The front panel is called the panel, and the back panel is called the back panel; In the core plate, the fiber direction parallel to the surface plate is called long core plate or middle plate. When forming the cavity table slab, the panel and back plate must face outward tightly.

(1) It is divided into ordinary plywood and special plywood according to its use.
(2) Ordinary plywood is divided into Class I plywood, Class II plywood and Class III plywood, which are weatherproof, water-resistant and non-hygroscopic plywood respectively.
(3) Ordinary plywood is divided into unshanded board and sanded board according to whether the surface is sanded or not.
(4) It is divided into coniferous plywood and cabinet plywood according to tree species
Characteristics of plywood
1. High strength and dimensional stability: plywood is an engineering wood product made of thin veneer, called layer.
2. High impact resistance: The high impact resistance of plywood makes it a popular material for construction and manufacturing applications.
3. Flexibility or flexibility: Plywood is flexible, but it has not reached the level that it can be rolled up.
4. Fire resistance: fire-resistant plywood is a kind of plywood designed for fire protection.
5. Sound insulation and heat insulation: Plywood is a solid and lightweight panel material made of thin wood. It is an excellent thermal insulation material because it allows heat to pass through the panel.

Advantages and disadvantages of plywood:
advantage:
Plywood is light in texture, strong in bending resistance, beautiful in appearance and texture, not easy to crack, stable and not easy to deform. Plywood not only has the beautiful pattern of wood, but also makes full use of wood and reduces costs. In the process of making plywood, it is not easy to produce fragments. It is a good way to save wood to make reasonable use of log resources and improve the utilization rate of wood. The plywood after manufacturing can withstand high temperature and climate change, and is not easy to break after a long time. It can be used for planes, trains, ships and cars, as well as home decoration and containers.
Disadvantages:
Plywood, as a plain board, usually needs finishing treatment when it is made into a wardrobe. The surface of plywood is not smooth enough compared with wood and density board, so its cleanliness is not very good, and it is not suitable for the use of single-sided parts, such as cabinets, doors and windows.