In order to ensure a high panel quality, a pre-pressing is usually carried out before the actual pressing. The mat made of flakes, fibres or strands is pre-pressed before it is transferred to the press; this is also referred to as deaeration. This is done by belt pre-presses. These compress the mats, some of which are very thickly spread, and reduce their thickness. Preheating of the mat is also possible. This increases the production capacity.
In the press, the mat is then pressed at high pressure to produce a uniform board with the desired thickness. Under the influence of pressure and temperature the glue hardens; the wood particles are also plasticized and remain permanently deformed. Two types of presses are used in the production of wood-based panels: the simpler multi-opening presses and the continuous presses. In recent years, continuous presses have become more and more popular. The advantages of this type of press are the high output as well as the elimination of idle times (in contrast to multi-opening presses), so that a very high output is possible even with thin boards. Multi-opening presses are still used for low production volumes and special products.
