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Why is plywood deformed?

Time : 2022-07-18 Hits : 79


Plywood is a three-layer or multi-layer board-like material that is made of wood segments into veneers or sliced into veneers, and then glued with adhesives. The fiber orientations are glued perpendicular to each other. Plywood is often used in furniture production, fast packing, steel side box production, etc., because the use of a large amount of adhesive is likely to cause excessive formaldehyde emission, so the environmental protection of plywood is very concerned when people choose furniture. Plywood has great strength and good flexibility. MDF is well-proportioned and suitable for production and processing. It is one of the three major artificial boards. So what causes the deformation of plywood?

1. Deformation caused by the difference in water content in some internal areas.
In the production of plywood, such as particle board scraps and fiber parts of medium density fiberboard, the drying area is uneven, or uneven in the whole process of sizing. In the production of plywood, the veneer coating is uneven, etc. There are differences in water content, the curing of the glue and the evaporation of water content are different, and the stress is asymmetrical, resulting in deformation.


2. Improper hot pressing process or deformation caused by the influence of the press itself.
During the whole pressing process of plywood, due to the conditions of the press itself, such as deformation of the pressing plate, insufficient temperature of individual hot pressing plates, or deformation caused by uneven pressure, or improper grasp of the hot pressing process, too high or too low temperature, Deformation caused by excessive pressure, etc.

3. Deformation caused by structural asymmetry.
Structural asymmetry is a key factor that causes internal stress in the board. For example, the surface and back layers of medium density fiberboard and particleboard are different in size and size, and the upper and lower sides of the neutral layer of plywood are different in terms of tree species, veneer fiber arrangement orientation, thickness, moisture content, number of layers, and production methods. The board has twist lines, etc., which is also the key reason for warping deformation.


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