The shortage of natural wood for the production of inexpensive furniture has led to the emergence of wood-particle boards in the middle of the last century. This relatively cheap type of lumber is known to every homeowner today.
European countries in the 40s of the last century used plywood and wood to make furniture, but faced with a rise in price and insufficient supplies of these materials to their factories. German engineer Max Himmelheber worked for several years to create a durable and affordable composite material. According to the technology developed by him, sawdust and phenolic resins were used to create chipboard.
GOST 10632 89 regulates the content of free formaldehyde in 100 g. particleboard plates of class E1 - up to 10 mg, class E2 - up to 30 mg.
Production consists of several stages:
- sawdust production;
- sorting and drying of raw materials;
- connection of chips with glue;
- carpet formation;
- hot pressing of plates;
- cooling;
- grinding and cutting;
- packaging.
- Getting chips
For sawdust use any waste lumber. Non-business wood is freed from bark, cut into meter-long sections and placed in a hydrotreatment pool. Chips in the machines are cut parallel to the wood fibers from half-meter sections. More than half of the chipboard is made up of large chips, the middle of three layers is formed from it. The outer layers are composed of finer, finer quality chips. Sliced shavings enter special mills, where they split in width with hammers and become smoother.
- Drying
Sawdust from woodworking enterprises also comes to special silos for collecting chips. For drying, the chips enter the unit through the conveyor, where they are mixed and blown with hot air. Large particles are separated from normal and returned to the grinder.
- Chip and glue carpet formation
Dry chips are metered into the mixer, and adhesive - synthetic resin - is also fed there. To glue the chip evenly, it is sprayed with compressed air. Glue coated chips are placed on a vibrating conveyor.
- Pressing and cooling
The carpet is formed on four cold presses:
- the bottom layer of the carpet is formed in the first;
- the second and third presses form a second layer of coarse chips;
- in the fourth press, a third, outer layer of the carpet is formed.
Next, the carpet of three layers falls on the sealing press, the thickness of the composite is reduced by three. The heated and moistened carpet comes under a hot press. The temperature in the chamber is 150 degrees Celsius, and the pressure is 20 kg per square centimeter of carpet.
Moisture, quickly evaporating under pressure, forms a steam boost. Steam penetrates into each layer of the carpet, reducing its exposure to the press.
When the pressing process ends, the hot plate is cooled by a stream of cold air. The finished plate is polished.
Laminated by a chipboard (LDSP)
Thanks to lamination, the plate receives a lining and does not need further decoration. The lamination process is not simple and consists of several stages:
- surface and paper preparation;
- creating packages;
- lamination under the press.
Training
The polished surface of the plate is plastered and sanded again. For lamination, sulfate, sulfite and finishing paper is used. It can be monophonic or imitating a surface of a tree. The intaglio printing method allows you to get a three-color pattern. Before lamination, the paper is impregnated with resins on special machines. Resins are absorbed into the paper, completely removing air from its surface. At first, a viscous liquid covers one side of the paper, air exits on the other side, then the paper is completely immersed in the resinous substance. The resin-impregnated paper is dried in a convection chamber.
Creating packages
Before loading into the press, a package of the following layers is formed:
- chipboard sheet;
- paper base in the form of large sheets on both sides of the sheet;
- decorative and finishing layers are laid only on the front side of the sheet;
- sheets of metal.
Several packages are loaded into the laminating unit, asbestos gaskets are laid between them.
Chipboard lamination under press
Plates in packages are placed under a hydraulic press, where for 15 minutes they are exposed to a temperature of 135-210 degrees Celsius, and the pressure in the installation is 25-28 MPa.
Lamination at different enterprises is carried out using two technologies:
- using water vapor;
- without steam.
Completes the process of cooling, packaging, storage.
Other cladding methods
Caching is the same lamination, but it is easier and faster. The surface of the plate is covered with glue, paper impregnated with resins is laid on it, it is leveled by rollers. After that, the stove goes under a cold or hot press.
Particleboard surface is covered with PVC films, but such cladding is more susceptible to mechanical damage. Another type of cladding is natural veneer coating, the process is similar to lamination.
All chipboard boards seem the same, but they are divided into types and grades, they can be fire and water resistant. Plates are relatively inexpensive, have a smooth surface, and are durable: they do not dry out and do not twist, therefore they are a universal material for furniture production.
Video material “Production of furniture chipboard”: