Plywood, also known as multi-layer plywood and multi-layer wood plywood, is a multi-layer board that was first used in the decoration industry. The multi-layer board is a veneer (the veneer is the basic unit) that is cut from various logs and wood squares, and then glued with a special phenolic resin adhesive for multi-layer boards. In order to ensure uniform characteristics and stable shape of multi-layer boards, multi-layer board manufacturers must comply with three production principles in the process of producing multi-layer boards: first, symmetry; second, adjacent layers of veneer fiber directions are perpendicular to each other; The number of layers is usually an odd number of layers.
The commonly used types of multi-layer boards are plywood and plywood. The main materials are beech, camphor, eucalyptus, poplar, eucalyptus, etc. The usual length and width specifications are 1220 × 2440mm, and the thickness is generally divided into 3 ccs, 5 PCT board, 9 PCT board, 12 PCT board, 15 PCT board, and 18 PCT board (1 PCT is 1 mm). The birth of multi-layer boards has greatly improved the utilization rate of wood (1m3 multi-layer boards can be used instead of 3~4m3), which is the main way to save forest resources.
In order to make full and reasonable use of forest resources to develop multilayer board production and make the best use of materials, the newly formulated national standard GB/T 9846-2015 was officially released in 2015. Laminates are divided into multi-layer boards for painting (used for furniture, sewing machine tabletops, and various electrical appliances whose surfaces need to be painted with transparent coatings), multi-layer boards for decoration (used as decoration materials for buildings, furniture, vehicles, and ships) ), general multi-layer boards (suitable for packaging, lining, and other purposes) and veneer decorative multi-layer boards (used as high-grade decorative materials for buildings, furniture, vehicles, ships, etc.).
Advantages and disadvantages of multilayer boards
advantage:
1. In the production process of multi-layer boards, it is not easy to produce sawdust, which can make reasonable and effective use of log resources, improve the utilization rate of natural wood, and is an important way to save wood.
2. The multi-layer board has light bulk density, good bending resistance, convenient transportation and construction, and beautiful texture, which makes up for some natural defects of wood and has good decorative properties. In some structural parts that need to bear weight, the use of a thin core board will have more strength.
3. The boiled multi-layer board has strong weather resistance, high-temperature resistance, and durability. Widely used in aircraft, ships, trains, automobiles, home improvement, construction, and containers.
shortcoming:
1. There is no MDF on the surface of the multi-layer board, and the solid wood board is clean and smooth, which is not suitable for cabinet facades, window sashes, etc.
2. Multi-layer boards that have not been fully dried may have problems such as substandard quality and production process, resulting in serious deformation of the board during use, and it is difficult to adjust it with external forces.
Multilayer board production process
Veneer finishing → gluing and assembling → pre-pressing → hot pressing → trimming → sanding → inspection and grading → packaging and storage.
Veneer finishing: veneer finishing includes cutting, splicing, and repairing. This step is to cut the dried veneer and pieces of veneer into standard veneers and applicable veneers, and the narrow veneer is spliced into a whole. A single veneer, the defective whole veneer can be repaired to meet the quality requirements of the process.
Hot pressing: The glued slabs are firmly glued together by a certain temperature and a certain pressure. During hot pressing, as the temperature and moisture content of the slab change, the wood is gradually compressed, and the thickness of the slab gradually decreases.
Trimming: Cut the hot-pressed wool board into specification boards.
Sanding: Sand the surface of the multi-layer board to make the board surface smooth and beautiful. .
How to choose a multi-layer board
1. Look at the material: When choosing, pay attention to the material, pattern, and color of the panel. There are differences between the front and back of the multi-layer board. When choosing, the board should be smooth and smooth, with clear wood grain, not rough, flat, and no stagnation. The multi-layer board should not have defects such as damage, bumps, hard wounds, scars, etc., and the grade and category of the multi-layer board should be reasonably selected according to the environment and cost.
2. Listen to the sound: The multi-layer board that does not lose glue should be selected. If the sound is brittle when knocking on each part of the multi-layer board, it proves that the quality is good without degumming.
3. Look at the type: Generally speaking, the number of layers of multi-layer boards is the base number, of course, there are occasionally even numbers, so when choosing, the product can be judged by the number of layers.
4. Look at the type: The products formed by different environmental factors are different. For home decoration, it is best to choose a multi-layer board with precious wood slicing and veneer, and it must comply with GB50222 "Building Interior Decoration Design" Fire Code.