Comprehensive understanding of plywood

Comprehensive understanding of plywood

2023-02-07
Comprehensive understanding of plywood
Plywood, also known as plywood, fine-core board, plywood, and five-ply board, is a three-layer or multi-layer odd-numbered laminated material that is made by peeling wood segments into veneer or cutting wood into thin wood and gluing with adhesive. The fiber directions of the adjacent layers of veneer are mutually perpendicular.
In the same plywood, veneers of different species and thickness are allowed to be pressed together at the same time, but the symmetrical two-layer veneers require the same species and thickness. So when looking at plywood, take the middle veneer as the center, and the veneers on both sides are uniform in color and thickness.
In terms of the use of plywood, most of the major industrial developed countries apply it to the construction industry, followed by shipbuilding, aviation, trunk, military, furniture, packaging and other relevant industrial sectors. China's plywood products are mainly used in furniture, decoration, packaging, building templates, car boxes, ships, and production and maintenance.
The length and width specifications are generally 1220 × 2440mm；
The thickness specifications generally include: 3mm, 5mm, 9mm, 12mm, 15mm, 18mm, etc.
Plywood raw materials
In the finished plywood products, the inner veneer except the surface board is collectively referred to as the middle board; It can be divided into short medium plate and long medium plate.
Common types of plywood veneer are: poplar, eucalyptus, pine, miscellaneous wood, etc.
Plywood veneer can be divided into special grade, first grade, second grade and third grade according to appearance grade.

Special grade: the board surface is flat, without holes/seams/skins/dead knots and large burrs;
Level I: the board surface is flat, without bark/bark holes, and has seams and knots;
Level II: the board surface is basically regular, with a small amount of bark and bark holes;
Level III: the length and width of the board are incomplete, and there are many bark, bark holes and defects
Plywood surface board is used as the outermost veneer of plywood, which is divided into panel and back board.
Common wood species used for plywood surface board: Augustan, peach core, poplar, birch, red olive, osmanthus fragrans, ice candy, pencil-cypress, big white wood, tangwood, yellow tung, yellow olive, Klonewood, etc.
Common wood colors of plywood surface board include: peach, red, yellow, white, etc.
The manufacturing process of plywood is generally as follows:
Spin cutting: first cut the log into thin veneer.
Gluing: apply glue on the cut veneer
Embryo: combine the glued veneer together.
Cold pressing: cold pressing the combined veneer into wood.
Hot pressing: the cold pressed wood shall be hot pressed again.
Sanding: after hot pressing and cooling, saw the edge, and then sand the surface of the plate
Plywood is made of glued veneers crosswise and crosswise in the direction of wood grain. It is pressed under the condition of heating or not heating, which can largely overcome the defects of wood, improve the utilization rate of wood, and save wood.
Plywood is made of multi-layer lamination, so it is much cheaper than solid wood.
The physical and mechanical properties of plywood in vertical and horizontal directions have little difference, which can greatly improve and improve the physical and mechanical properties of wood, with good dimensional stability and anti-warping and cracking.
Plywood can retain the natural texture and color of wood, with flat shape and large width and thickness, so it has strong covering ability and convenient application and construction.

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