PLYWOOD PRODUCTION PROCESS
Plywood is a board made from thin sheets of construction veneers, which are bonded in layers to create a strong and stable board. Veneers used for plywood construction are cut from a log for constructional or decorative purposes.
The two most common methods used for veneer production are called saw and rotary cutting. Constructional veneers on the other hand are cut using the second method named rotary cutting. The knife blade peels thin sheets of wood and it is an efficient way to produce veneers, as they can be cut to any width.
Plywood is most commonly made using an odd number of veneers, three being the minimum. However, the number of veneers used depends on their thickness and the finished plywood board. The veneers are bonded with an adhesive at right angles to one another to reduce the shrinkage and improve the strength. Various species can be used for plywood production, where the face and core veneers may be made from different species or the same species can be used for the entire board construction. The surface of the plywood board consists of veneers called face plies.
Depending on their quality, the ply of better quality is known as the "face" and the other is referred as the "back". To indicate the quality of the plies, a letter code is used to mark the grade. The grading system uses the letters E, B, BB, and C where grade E (elite) classifies the best quality and grade C indicated the poorest quality. The grades only refer to the appearance of the face plies and do not indicate the structural performance of the plywood board. Plywood is constructed in a wide range of different sizes. The most common dimensions (mm) are: length – 1525, 2440 and 3010 and width – 1220, 1525. The thickness of plywood can range from 3-40 mm depending on the area of use.