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Multi-layer plywood production process:
Veneer finishing → gluing → assembling → pre-pressing → hot pressing → sanding → lamination → secondary hot pressing → edge trimming → packaging and storage.
Blockboard production process:
Thin wood strips → splicing on the glued panel → pre-pressing → hot pressing → sanding → lamination → secondary hot pressing → trimming → packaging
Inventory.
Veneer finishing: Veneer finishing includes cutting, assembling and repairing. Cut dry strip veneer and piece veneer into specification veneer and splicable veneer, narrow strip veneer is spliced into whole veneer, defective whole veneer can be repaired to achieve the quality of craftsmanship Require.
Gluing: Apply glue to the classified veneer through a glue applicator, mix evenly with melamine waterproof glue and flour in an appropriate proportion, and add red powder to distinguish it, so that the face is evenly glued. Group blank:
The glued veneer is laid on the case to the size and specification required by the customer, and the complementary staggered method is used for splicing and repairing to make the multi-layer plywood structure stronger. Preload:
The plywood is cold-pressed first, and then put into a pre-pressing machine for a proper time through a certain pressure.
Processing loss: In the whole production process of plywood, log sawing, veneer rotary cutting, veneer drying and veneer finishing, hot pressing, edge trimming, and sanding have an impact on wood loss, which is divided into tangible loss (with processing remaining physical) and invisible losses (drying and compression). Timber loss is related to factors such as log species, log specifications, equipment conditions, process technology, and finished board specifications.
Log sawing: The length of imported logs is generally more than 6 meters. It should be sawed according to the length and quality required by the process. The cut wood should be the length of the finished plywood plus the processing allowance. For example, the finished plywood with a width of 1220mmX2440mm, the length of the wood segment is usually 2600mm or 1300mm. The length of the log and the curvature and defects of the log directly affect the yield of plywood. The waste generated includes small wood segments, truncations and sawdust, etc. The loss rate of sawing logs is generally 3~10%.
Veneer rotary cutting: the most widely used veneer in plywood production is the veneer produced by rotary cutting method, the thickness of the front and back panels
It is generally about 0.6mm, and the thickness of the core board and the long and medium board is generally about 1.8mm. The loss of this process is the largest. First, due to the out-of-roundness of the wood segment, a considerable part of the broken veneer cannot be used; second, the end loss is caused by the clamping of the rotary cutter to both ends of the wood segment; the third is the loss of the wood core. The waste generated by the veneer peeling is broken veneer and wood core. It can be seen that the loss of veneer peeling is related to the material, diameter and equipment performance of the wood segment, and the loss rate of this part is 15%~25%.
Veneer drying: The moisture content of the veneer after rotary cutting is very high, and the veneer must be dried to meet the requirements of the gluing process. The size of the wood becomes smaller after drying, which is called drying shrinkage. As the moisture content decreases, the length, width and thickness of the veneer will shrink. The shrinkage loss is related to the tree species of the veneer, the moisture content of the veneer and the thickness of the veneer. Dry shrinkage loss rate is generally 4% to 10%.
Veneer finishing: Veneer finishing includes cutting, assembling and repairing. Cut the dried strip veneer and piece veneer into specification veneer and splicable veneer, the narrow veneer is spliced into a whole veneer, and the defective whole veneer can be repaired to achieve the process. Quality requirements. The amount of waste veneer produced in this process is related to factors such as the material of the log, the quality of the rotary-cut veneer, the quality of the dried veneer, and the operator's familiarity with the veneer standard. The loss rate is generally 4% to 16%. The loss rate of this process of directly importing veneer into plywood is generally 2% to 11%.
Hot pressing: glue the good and bad boards of the glued group together firmly through a certain temperature and certain pressure. During hot pressing, as the temperature and moisture content of the board change, the wood is gradually compressed, and the thickness of the board gradually decreases. This loss is the compression loss, which is related to the hot pressing temperature, unit pressure, hot pressing time, tree species and moisture content of the plywood. The loss rate is generally 3% to 8%.
