Structure and Selection of Special-shaped plywood
Special-shaped plywood is one of the common materials for furniture and office furniture. The raw materials are mainly camphor, willow, poplar, eucalyptus, etc. However, its composition principle should be strictly followed in the design, which mainly includes the following two points:
1. Odd Layer Principle: Because the plywood structure is the fiber direction of adjacent veneers hanging mutually, and must conform to the principle of symmetry, the total number of plywood layers must be odd. Such as: three-ply, five-ply, seven-ply, etc.
2. Symmetry Principle: No matter the thickness, number of layers, manufacturing method, fiber direction and moisture content of veneers on both sides of symmetry central plane, they should correspond to each other. That is to say, the stress magnitude of corresponding layers on both sides of symmetry central plane of plywood is equal. Therefore, when the moisture content of plywood changes, its structure is stable, and there will be no deformation, cracking and other defects. On the contrary, if there are some differences between the corresponding layers on both sides of the symmetrical central plane, the stress of the veneers on both sides of the symmetrical central plane will be unequal, and the special-shaped plywood will be deformed and cracked.
Key points for selection of profiled plywood:
1) Plywood of different types, grades, materials, decorations and formats are selected according to the engineering properties, using parts and environmental conditions.
2) Plywood with precious wood veneer should be selected for decoration.
3) Plywood used for interior decoration of buildings should comply with GB50222 “Code for Fire Protection of Interior Decoration Design of Buildings”.
4) In the case of hidden part which may be damped and high water-proof requirement, the type I or II plywood should be selected, and the type I plywood should be selected for outdoor use.
5) Transparent varnish (also known as clear oil) is needed for panel decoration, so as to retain the natural color and texture of wood surface, the selection of panel material, pattern and color should be emphasized; if the pattern and color of panel need not be considered, plywood grade and category should also be selected reasonably according to the environment and cost.