Plywood
Hardwood Plywood (abbreviated FU), also known as plywood, a symmetrically constructed wood material is of several cross-bonded layers of peeled veneers. The number of plies is therefore almost always odd (except for a thicker middle layer is made of technical reasons from two parallel layers). Due to the number and arrangement of veneer layers, the disk structure and its specific strength characteristics result. A plate 12 mm thick and with at least five layers is referred to as a multiplex panel.
Properties and qualities
By cross- gluing the veneers, the wood is highly restricted in its natural properties of swelling and shrinkage and thus ensures good dimensional stability. In addition, the cross gluing causes a flexural strength comparable to the two main axes of the plate.
Plywood can be coated and surface treated. The fiber direction of the two outer covering layers has to necessarily run parallel, so that the board does not warp. In addition, on both sides the same coating material should be used.
Special design of veneer plywood, for example, the construction plywood (BFU ) with very high bending strength, metal- armored veneer plywood or vapor barrier plates, which have a middle layer of aluminum sheet. Molded plywood also consists of 90 ° crosswise glued layers of veneer - here come mainly book peeled veneers are used.
Production
The dried wood layers are glued, laid crosswise over one another and pressed under heat. Special presses enable the production of molded plywood. The veneer sheets are not like a plate pressed flat but shaped in particular forms to seats, panels etc..
Use
Because of its good dimensional and form resistance takes this material in furniture and interior design for back walls, linings and fillings using, in addition for furniture carcasses and worktops. The material is also available as exterior plywood and can be used as such in damp, wet or cold room for use. In addition, he finds in the motor vehicle and wagon as well as packaging material application.
Economic Importance
In terms of the total production of plywood veneer panels made with a production of 22,000 m³ in 2008 about 12.6 % of. In Germany there are 2009 six manufacturers of veneer plywood.