Technological process of plywood First, the process flow of log production to produce plywood: log → log sawing → wood segment cooking → wood segment peeling → veneer rotary cutting → veneer drying → veneer finishing → glue grouping → pre-pressing → hot pressing → edge cutting →Cut light→Check grade→Package and storage.
Second, the veneer processing and production process of plywood: veneer finishing → glue coating group billet → pre-pressing → hot pressing → cutting into → sanding → inspection classification → packaging and storage. 1. Processing process loss: Throughout the production process of plywood, logs are cut off, veneer rotary cutting, veneer drying, veneer finishing, hot pressing, trimming, and cutting have an impact on wood consumption, which is divided into physical loss ( The loss of wood is related to the original wood species, wood specifications, equipment conditions, process technology, and finished board specifications. 2. Log sawing: The length of imported logs is generally more than 6 meters. The length and quality of the process should be used for sawing. The intercepted wood segments should be the length of the finished plywood plus the processing allowance. For example, finished plywood with a width of 1220mmX2440mm, the length of the wood segment is usually 2600mm or 1300mm. The length of the logs, the curvature of the logs, and defects directly affect the plywood output rate. The generated waste materials include small wood segments, truncated heads, and sawdust. The sawing loss rate of logs is generally 3 to 10%. 3. Rotary cutting of veneer: the most widely used in the production of plywood is the veneer produced by the rotary cutting method. The thickness of the face and backboard is generally about 0.6mm, and the thickness of the core board and the long and medium board is generally about 1.8mm. The largest consumption of the veneer is that, due to the roundness of the wood segment, a considerable part of the broken veneer cannot be used; second, the end of the clip is clamped by the chuck of the rotary cutter to separate the wood segment; and third, the core loss. The waste generated by the rotary cutting is broken veneer and wood core. It seems that the loss of veneer rotary cutting is related to the material, diameter and equipment performance of the wood section. The loss rate of this part is 15%~25%. 4. Drying of veneer: The length of veneer after spinning is very high, and the veneer must be dried to meet the requirements of the gluing process. After drying, the size of the wood becomes smaller, which is called shrinkage. As the ratio decreases, the length, width and thickness of the veneer will shrink. Shrinkage loss is related to the veneer species, elongation rate and veneer thickness. The shrinkage loss rate is generally 4% to 10%. 5. Veneer sorting: Veneer sorting includes shearing, jigsaw and repair. Cut the dried strip-shaped veneer and zero-piece veneer into specification veneer and detachable veneer. The narrow strip veneer is spliced into the amount of waste veneer and log material generated by this process, and the quality of the veneer is cut , Dry veneer quality and operator's familiarity with veneer standards and other factors, the loss rate is generally 4% ~ 16%. The processing loss rate of directly imported veneer processed into plywood is generally 2%~11%. 6. Hot pressing: the slabs of the glue-coated blanks are firmly glued together by a certain temperature and a certain pressure. When hot pressing changes the temperature and overlap rate of the slab, the wood is gradually compressed, and the thickness of the slab gradually decreases. The item loss is compression loss, which is related to the factors such as the hot pressing temperature, unit pressure, hot pressing time, tree species and coverage of plywood. The loss rate is generally 3%~8%. 7. Trimming: Cut the hot-pressed wool into specifications. The amount of corner scraps of the tailor is related to the plywood processing margin and the size of the plywood. The plywood width is reduced, and the trimming loss rate is smaller, generally 6%~9%.
8. Sanding: sanding the surface of plywood to make the board surface smooth and beautiful. The waste material produced by this process is sanding powder. When the quality of the veneer is good, the sanding amount is small, and the sanding loss rate is generally 2% to 6%.
