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advantage and disadvantage of plywood
Advantages of plywood
1. Plywood has all the advantages of natural wood, such as light weight, high strength, beautiful texture, insulation, etc., and it can make up for some of the natural defects of natural wood such as knots, small breadth, deformation, large differences in longitudinal and vertical mechanics, etc. .
2. Plywood production can reasonably use logs. Because it has no sawdust, it can produce 1 cubic meter of plywood per 2.2-2.5 cubic meters of logs, which can be used instead of about 5 cubic meters of logs to be used as a board, and for every 1 cubic meter of plywood products, it can also produce residues of 1.2-1.5 cubic meters. Rice, which is a good raw material for the production of MDF and particle board.
Defects of plywood
1. Low glue strength: mainly caused by poor glue quality. The hot pressing conditions are not well controlled. For example, the hot pressing temperature is low, the pressure is insufficient, and the glue pressing time is too short. If the moisture content of the veneer is too high, the amount of glue applied is insufficient, the veneer quality is poor, and the aging time is too long or too short, which will also reduce the bonding strength.
2. Bubbling and local glue opening: The reason is that the pressure reduction speed is too fast, the glue pressure time is insufficient, the veneer moisture content is too high, there are blank spots when the glue is applied, or there are inclusions on the veneer, sticky dirt, or the use of pine veneer Caused by excessive temperature.
3. Warpage of plywood: It is caused by the large internal stress of plywood. The reason is that the moisture content of the front and back panels is inconsistent, the veneers of different tree species are unreasonably matched, the veneers have twist patterns, the temperature of individual hot pressing plates is not enough, and the stacking of the plates is not equal.
4. Gluing of the corners: This defect is caused by insufficient pressure on the corners of the pressure plate. The slab corners in each interval are not aligned. The slabs are skewed when loaded and uneven pressure is applied. Insufficient squeezing when cutting, weak glue relay, lack of glue in corners, premature drying of glue, low temperature in local areas of the pressing plate, etc.
5. Penetration: The reason is that the glue is too thin, the amount of glue is too large, the cracks on the back of the veneer are too deep, the moisture content of the veneer is too high, the aging time and the pressure are too large.
6. Lamination and separation of core board: The reason is that the gap is too large or too small when manually arranging the cores with zero pieces, the core plates are misaligned or overlapped when the plates are installed, and the edges of the zero plates are uneven.
