Introduction of plywood
Plywood, also known as plywood and wood plywood, is the first plywood used in decoration industry. Plywood is a kind of veneer (veneer is the basic unit) which is made up of various logs, wood square rotary cutting or planing, and then bonded with phenolic resin adhesive for plywood. In order to ensure the uniformity and shape stability of plywood, plywood manufacturers must abide by three production principles in the production of plywood: one is symmetry; the other is that the fibers of adjacent veneer layers are perpendicular to each other; and the third is that the number of layers is usually odd.
Commonly used plywood types have three plywood, five plywood, the main material is: beech, camphor, willow eucalyptus, poplar, eucalyptus, etc., usually length and width specifications are: 1220 x 2440 mm, thickness is generally divided into 3 centimeters, 5 centimeters, 9 centimeters, 12 centimeters, 15 centimeters and 18 centimeters (1 centimeter, 1 millimeter). The emergence of plywood greatly improves the utilization rate of wood (1 m3 plywood can be used instead of 3~4 m3), which is a main way to save forest resources.
In order to fully and reasonably utilize forest resources to develop plywood production and make full use of wood, the new national standard GB/T 9846-2015 was formally issued in 2015. According to the use of plywood, plywood is divided into plywood for finishing (furniture for which transparent coating is required on the surface, sewing machine table board and plywood for sewing machine). Plywood for decoration (used as decoration materials for buildings, furniture, vehicles and ships), plywood for general use (suitable for packaging, padding and other purposes) and veneer for decoration (used as advanced decoration materials for buildings, furniture, vehicles, ships, etc.).
Advantages and disadvantages of plywood
1. Plywood is not easy to produce sawdust in the manufacturing process. It can make rational and effective use of log resources and improve the utilization rate of natural wood. It is an important way to save wood.
2. Plywood has light bulk density, good bending resistance, convenient transportation and construction, beautiful texture, which makes up for some defects of wood naturally generated and has good decorative properties. In some structural parts which need to bear load, the use of thin core board will be more intensive.
3. The boiled plywood has strong weather resistance, high temperature resistance and durability. It is widely used in aircraft, ships, trains, automobiles, home decoration, buildings and containers.
1. The surface of plywood has no density board and solid board is neat and smooth. It is not suitable for cabinet doors and window fans.
2. If the plywood is not fully dried, there may be some problems such as unqualified quality and production technology, which will lead to serious deformation of the plywood in use, and it is difficult to adjust the plywood by external forces.
Production process of plywood
Veneer finishing glue coating billet preloading hot pressing trimming sanding inspection grading packaging and storage.
Veneer finishing: Veneer finishing includes shearing, splicing and repairing. In this process, the dried veneer and zero veneer are cut into specification veneer and spliceable veneer. Narrow veneer is spliced into whole veneer. The defective veneer can be repaired to meet the quality requirements of the process.
Hot pressing: The glue-coated slabs are firmly bonded through a certain temperature and pressure. With the change of slab temperature and moisture content during hot pressing, wood is gradually compressed and slab thickness is gradually reduced.
Cutting: Cut the hot-pressed wool board into specifications.
Sanding: Sanding the plywood surface to make it smooth and beautiful.
How to Select Plywood
1. Material quality: When choosing plywood, we should pay attention to the material, pattern and color of the panel. Plywood has positive and negative differences. When choosing plywood, we should choose plywood with smooth and smooth surface, clear wood grain, non-rough, flat and without hysteresis. There should be no defects such as breakage, bruising, hardness and scars. At the same time, we should also make plywood according to the environment and manufacture. Choose the grade and type of plywood reasonably.
2. Listen to the sound: Choose the plywood which is not free of glue. If the sound is crisp when you tap the parts of the plywood by hand, it proves that the quality of the plywood without degumming is good.
3. Look at the type: Generally speaking, plywood layers are the base number, of course, occasionally even number, so when choosing, products can be judged by the number of layers. The commonly used types of building plywood are three plywood, five plywood and so on.
4. Look at the types: The products made up of different environmental factors are different. For home decoration, it is best to choose precious wood products, sliced veneer plywood, and to comply with the GB50222 “Code for Fire Protection in Building Interior Decoration Design”.