What is Plywood

What is Plywood

Plywood pictures

Plywood is a three-layer or more thin board made by peeling logs into veneers or planing wood into veneers, and then gluing them with adhesive. Usually, an odd number of veneers are used, and the fibers of adjacent layers of veneers are arranged perpendicular to each other. Therefore, there are three-ply, five-ply, seven-ply and other odd-numbered plywood.

From a structural point of view, the outermost veneer of plywood is called the surface board, the front surface board is called the top board, which is made of the best quality veneer. The back surface board is called the back board, which is made of the second-best quality veneer. The inner veneer is called the core board or middle board, which is made of the worst quality veneer.

The manufactured plywood has the following characteristics:

1. Plywood has all the advantages of natural wood, such as light weight, high strength, beautiful texture, insulation, etc., and can make up for some natural defects of natural wood, such as knots, small width, deformation, large differences in longitudinal and transverse mechanical properties, etc.

Second, plywood production can make rational use of logs. Because it does not contain sawdust, every 2.2-2.5 cubic meters of logs can produce 1 cubic meter of plywood, which can replace about 5 cubic meters of logs sawn into boards. And every cubic meter of plywood produced can also produce 1.2-1.5 cubic meters of residue, which is a good raw material for producing medium-density fiberboard and particleboard.

Since plywood has the advantages of small deformation, large format, convenient construction, no warping, and good transverse tensile mechanical properties, this product is mainly used in furniture manufacturing, interior decoration, and various boards for residential construction. Secondly, it is used in industrial sectors such as shipbuilding, car box manufacturing, various military industries, light industrial products, and packaging.

How to choose plywood

At present, there are many kinds of decorative materials in the market, with different grades and prices. Even professional material purchasers of decoration companies are easily deceived. If you do not have certain identification knowledge, you will not be able to distinguish them.

Plywood is made of three or more layers of one millimeter thick veneer or thin board glued together by hot pressing. Common plywood includes three-ply board, five-ply board, nine-ply board and twelve-ply board (commonly known as three-ply board, five-ply board, nine-ply board and twelve-ply board in the market).

When choosing plywood, pay attention to the following points:

1. Plywood has two sides. When choosing, the plywood should have clear wood grain, the front side should be smooth and not rough, and it should be flat and smooth.

2. Plywood should not have defects such as breakage, bruises, hard spots, knots, etc.

3. There is no degumming phenomenon on the plywood.

4. Some plywood is made by sticking two veneers with different textures together, so when choosing, you should pay attention to the tight joints between the plywood and no unevenness.

5. When choosing plywood, you should pay attention to choosing plywood that does not loose glue. If the sound is crisp when you knock on the plywood, it proves that the quality is good. If the sound is dull, it means that the glue has loosened.

6. When choosing glued veneer panels, you should also pay attention to uniform color, consistent texture, and the color of the wood should be coordinated with the color of the furniture paint.

China Plywood National Standard: Plywood Grades

According to Plywood - Specification for classification by appearance of plywood for general use GB 9846.5-1988, ordinary plywood is divided into four grades according to the visible material defects and processing defects on the panel: special grade, first grade, second grade and third grade, among which first, second and third grades are the main grades of ordinary plywood.

The various grades of ordinary plywood are mainly determined according to the allowable defects on the panel, and the allowable defects of the back panel, inner veneer and processing defects of the plywood are limited.

The simple grade description and main uses of each grade of ordinary plywood are as follows:

Special Grade: Except for a few minor material defects (such as needle knots), no other defects are allowed. Suitable for high-end architectural decoration, high-end furniture and other wooden products with special needs;

First-class: Individual minor defects are allowed (such as needle knots, dead knots, worm holes, cracks, dents, indentations, etc.). Suitable for making high-end architectural decoration, high- and medium-grade furniture, various electrical appliance shells and other products;

Second grade: In addition to a small number of minor defects, some slightly more serious defects (such as patches, strips, and board edge defects) are allowed. Suitable for furniture, ordinary buildings, vehicles, ships, etc.;

Grade 3: More and larger defects are allowed, but the number and severity of defects must be within the corresponding limits and must not affect its use. Suitable for low-grade building decoration and packaging materials, etc.

The above four grades of panels should be sanded (scraped) smooth. Those with special needs do not need to be sanded (scraped) smooth or only need to be sanded (scraped) on both sides.

The backplane grade requirement is very low and a number of defects are allowed.