(1) Low glue strength: mainly caused by poor quality of glue. This problem can also occur when the hot pressing conditions are not well controlled, such as low hot pressing temperature, insufficient pressure, and too short pressurization time. Veneer moisture content is too high, the amount of glue is insufficient, the quality of the veneer is poor, and the aging time is too long or too short, which will also reduce the gluing strength.
(2) Bubbling and local glue opening: the reason is that the pressure relief speed is too fast, the pressurization time is insufficient, the moisture content of the veneer is too high, there are blank spots when gluing or there are inclusions and sticky stains on the veneer.
(3) Plywood warping: It is caused by the large internal stress of the plywood. The reasons are that the moisture content of the table back plate is inconsistent, the combination of veneer of different tree species is unreasonable, the texture of the veneer is distorted, the individual hot pressing temperature is not enough, and the board is stacked unequally.
(4) Corner glue: The main reason for this problem is that the pressure is insufficient due to the wear of the corners of the pressing plate, the corners of the slab in each interval are not aligned, the slab is placed skewed and subjected to uneven pressure when the board is loaded, the pressing degree is insufficient when the veneer edge is rotary cutting, the glue relay is weak, the corners are lacking glue, the glue dries up prematurely, and the local temperature of the pressing plate is low.
(5) Penetration: The reasons are low solid content of glue, too large sizing amount, too deep cracks on the back of the veneer, too high moisture content of the veneer, too long aging time and too much pressure.
(6) The amount of formaldehyde released exceeds the standard, which is related to the quality of the adhesive and the gluing process.
