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Film Faced Plywood Production
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The production of film faced plywood is a complex, multi-step process, and at each step it is important to strictly adhere to the production methods. Let us examine the production process of film faced plywood, using SVEZA plywood mills as an example, as SVEZA is a world leader in the production of birch plywood.To get more news about commercial plywood, you can visit boosterplywood.com official website.
The first machines for converting wood into veneer sheets and then into plywood were patented back in the 18th century. It is worth pointing out that almost all of their inventors were in some way connected to Russiai. Since it was invented, this technology has not changed, although the machines have been modernized and are now fully automated. This has reduced the need for manual labor at the production stage, and, as a result, the quality of the final product, the plywood, has been improved.
The beginning: preparation of raw materialsThe manufacturing process of film faced birch plywood requires the careful selection and preparation of raw materials. First, timber of the right size are selected. For the production of standard-sized plywood in Russia (1220mmx2440mm), timber with a diameter of 20-40 cm and a length of 5.2 m are used (later on, these timber can be cut into logs with a length of 1.3m or 2.6m, which are needed for the production of long grain and cross grain veneer sheets of the required size).
The main stage of preparation is to soak the raw materials. This is done in a special pool (which is open or covered) for 24 hours. In summer, the temperature inside the pool is kept at 35-40оC and in winter at 40-45оC. To improve the quality of the veneer from which the plywood will be made, it is important at this stage to maintain the temperature at the right level and condition the wood for the right amount of time.
The softened logs are then transferred to the debarking and cutting department.
Debarking is done in the following way: the special knives of the debarking machine make a cut in the bark and remove it in a spiral-like fashion. The removed bark is used for heating not only the plant itself but also the adjacent buildings and even the whole village. This is the procedure, for example, at the Perm Plywood Mill (SVEZA Group). The boiler house serves the whole mill and the village Uralsky, in which the mill is located.
The debarked logs (almost without bark) are then passed through a metal detector. This helps to detect metallic impurities in the wood, such as nails, bits of wire etc., which could damage the equipment. When metal is detected, a signal is sent to the control panel of the machine, the conveyer is stopped, and the metal is removed by the operator.
After debarking, the wood is cut up. The processed raw materials are sawn into logs for the production of long grain and cross grain veneer sheets.The next step is to peel the veneer on special machines, where a thin, continuous strip of veneer is peeled off the prepared log. The thinner the veneer, the more layers the plywood of certain thickness will have. The more layers – the stronger the plywood. Russian birch veneer is the thinnest (1.2-1.5 mm) compared to other wood species (such as poplar veneer, which is 1.6-2.6 mm thick, and pine veneer, which is 2-4 mm thick).
At the peeling stage, quality control of the veneer is carried out: samples are taken daily to check its thickness and a number of other factors, and the results are compared to the standard. The settings of the peeling machines are then adjusted based on these results.
AAfter the peeling, automatic clippers cut the veneer strip into 1.3m x2.6m sheets for the production of 1220×2440 mm plywood. Long grain and cross grain veneer (for subsequent adhesion into a single sheet of plywood) is made on separate peeling lines.
“In the dryer, hot air is blown on the veneer sheets. Within 8-10 minutes, up to 90% of the moisture is eliminated from the wood. After drying, the veneer sheets are stacked onto a pallet or a conveyor belt (depending on the design of the dryer),“ says Natalia Andreeva, a film faced plywood manufacturing Typeer at the Fanplit Plywood Mill, which belongs to the SVEZA group.
After drying, the veneer is graded by a variety of properties, including the presence of knot-holes, cracks, etc. Many mills use automated equipment at this stage: the properties of each grade are programmed into a computer, which controls the process. During the grading, the surface is scanned and automatically evaluated, after which the scanner divides the veneer into different stacks. In this case, the operator just oversees the process. At this stage, the moisture level of the sheets is also assessed. If the veneer is not sufficiently dry, it is placed in a separate stack and fully dried later.
If defects are found during the grading stage, the sheets are not utilized and sent for repair instead. Veneer repairs can be performed on machines that are manually -operated, as well as on automated ones. The automated machines can improve the quality of the plywood, reducing expenses on manual labor 3-fold. Nowadays, equipment exists to repair veneer any size: standard – 5×5 feet (1525×1525 mm), and large – 5×10 feet (1500/1525×3000/3050 mm). After repair, the veneer is graded once again.