Thanks to chipboard production, none of the cut trees go to a waste disposal site – any wood product is used. Chipboards are made of chips, wood waste and timber.
The first stage of chipboard production is fragmentation of all wood waste using special chipping machines. The fragmentation results in a product which is called wood waste. Cutting machines turn all wood waste into uniform waste. Then waste goes to rotary machines where it turns into chips. This scheme is known as raw material-waste-chips. There is a slightly different scheme, for instance, with logs – logs-chips. Logs are laid on special machines with a cutter block which cuts logs into chips. The technology of chipboard production uses precise sizes which are obligatory for any plant-manufactured chips – their thickness must be 0.5 mm, width – 8 mm, length – from 5 to 40 mm.
There are special requirements for the shape and structure of chips as well. They must be absolutely flat (so that they can be glued to a board) and have a uniform thickness. Their surface must be smooth and even. By the way, the thickness of chips is measured using special devices as it is very important, especially for boards which will be further laminated. Raw chips are taken to a bunker where they are kept all the time before drying. They are delivered to bunkers using the pneumatic transport system. Then chips go for drying. Drying cameras dry wood chips until the humidity is 5%. The humidity of inner layers of chips must not exceed 25%, therefore, chips for different layers are dried in different drying machines. Convection drum-type driers burn liquified gas and have the average temperature of about +10000С.
Chips for the outer layer are heated and cooled more quickly. Chips for inner layers are heated more slowly and are kept in the drier for a longer period of time; they are cooled gradually. Pneumatic machines sort chips for inner and outer layers. Pneumatic machines differentiate chips according to humidity level. Next, chips are mixed with binding agents which are synthetic resin. These resins turn isolated chips into a uniform mass. Binding resins are applied to chips as liquid solutions.
Then, chips which have been treated with resin go to moulders. There chips which have been treated with resin are put on belt-type conveyors. Sometimes the line can use trays instead of belt-type conveyors: but this feature is going out of date – chips form a chip mat there. The chip mat is split into packages which then undergo hot pressing. After pressing, chips become extremely dense and hard and can be transported. By the way, only in recent years have chipboards been made from chips only; chips are glued with resins and pressed with hot press to make a board. Earlier, in the absence of such powerful hot presses and synthetic resins, chips were glued with a special glue, cooled for a long time and the weak construction from chips was glued to a thin wooden board.
The technology of chipboard production has changed over time and has significantly improved. Nowadays, after pressing, boards are put on the unloading line where they are cooled down, sanded and covered with special fixing agents and salts. After that, they are packed using the manufacturer’s packaging and delivered to shops. Earlier, the technology of chipboard production envisaged manual cutting and packing.