First, the process of plywood production from log processing: log-log sawing-wood segment cooking-wood segment peeling-veneer rotary cutting-veneer drying-veneer finishing-glued blanks-pre-pressing-hot pressing-trimming -Cut out-Check and grade-Pack and store.
Second, the process of veneer processing to produce plywood: veneer finishing-gluing blanks-pre-pressing-hot pressing-cutting-sanding-inspection grade-packaging and storage.
1. Processing process loss: In the entire production process of plywood, sawn logs, veneer rotary cutting, veneer drying, veneer finishing, hot pressing, trimming, and light cutting have an impact on the loss of wood. It is divided into tangible losses ( With processing residues) and intangible losses (dry shrinkage and compression). Wood loss is related to factors such as the original wood species, log specifications, equipment conditions, process technology, and finished board specifications.
2. Sawing of logs: Sawmills such as Log Sawing Equipment are often used. The length of imported logs is generally more than 6 meters. The length and quality of the logs should be sawn. The length of the log and the curvature and defects of the log directly affect the yield of the plywood. The waste generated includes small wood segments, stubs and sawdust. The sawing loss rate of the log is generally 3 to 10%.
Log Sawing Equipment
3. Rotary cutting of veneer: Veneer Rotary Cutting Machine is the most widely used veneer produced by plywood. The thickness of the front and back plates is generally about 0.6 mm, and the thickness of the core plate and the long middle plate is generally about 1.8 mm. This process has the largest loss. First, due to the roundness of the wood segment, a considerable part of the broken veneer cannot be used; second, the end of the wood segment is caused by the clamping of the chuck of the rotary cutting machine; The waste generated by veneer rotary cutting is broken veneer and wood core. It can be seen that the veneer rotary cutting loss is related to the material, diameter and equipment performance of the wood segment. This part of the loss rate is 15% to 25%.
4. Veneer drying: The moisture content of the veneer after spinning is very high, and the veneer must be dried to meet the requirements of the gluing process. After drying, the wood becomes smaller in size and is called shrinkage. Due to the reduced moisture content, the length, width and thickness of the veneer will shrink. Dry shrinkage loss is related to veneer tree species, veneer moisture content, and veneer thickness and other factors. The dry shrinkage loss rate is generally 4% to 10%.
5, veneer finishing: veneer finishing includes cutting, puzzle and repair. The dried strip veneer and zero veneer are cut into standard veneer and splicable veneer. The narrow veneer is spliced into a whole veneer. The defective whole veneer can be repaired to achieve the process. Quality requirements.
6. Hot pressing: At this time, the Plywood Hot Press Machine is mainly used to glue the slabs of the rubberized group through a certain temperature and pressure. As the temperature and moisture content of the slab change during hot pressing, the wood is gradually compressed and the thickness of the slab gradually decreases. The loss is compression loss, which is related to factors such as 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%.
7. Trimming: Cut the hot-pressed wool board into standard board. The amount of cut corner waste is related to the processing margin and the size of the plywood. The larger the plywood width, the smaller the edge loss rate.
8. Sanding: Sand the surface of plywood to make the surface smooth and beautiful. The waste generated in this process is sanding powder. When the veneer quality is good, the sanding amount is small.
The above is the production process of plywood, I hope to help everyone.