Particle board, often referred to as flat pressure plates (P2 to P7, formerly FPY ) denotes, are the largest and most famous subgroup of the wood chip materials. They are composed of different sizes of glued chips, which are pressed in the generally three to five layers for multilayer sheets. The outer layers are almost always consist of the finer chip material, especially if they are then coated for decorative purposes (for example in furniture ). Because of the massive wood composite is repealed, these plates in the direction of the plane of the plate, so the length and width of the plate, almost the same swelling and shrinkage properties, but also much lower strength than solid wood.
- 3.1 Wood processing
- 3.2 compression
- 3.3 Manufacturer
The particle board was invented in the 1930s by the German Max sky lift to increase the degree of recovery of trees, which at the time was about 40 percent. Since mainly wood waste such as wood chips, sawdust and branches are used for particleboard glue in addition, the recycling rate is now at about 80 percent.
The fundamentals that led to the development of Novopan chipboard, have been systematically developed since the late 1930s by Fred Fahrni ( 1907-1970 ), for which he later the Eidgenössische Technische Hochschule ( ETH) in Zurich awarded an honorary Doctor. In 1946, in Klingnau ( Switzerland ) is the first Novopan work that in the world the industrial production of large-format, three-layer particleboard recorded for the first time.
Since heaven Heber the manufacture of particle board was hardly developed. Technically worth mentioning is the development of the platen presses to modern Contiroll plants that have caused a productivity boost of about 50 percent. On the part of raw materials especially the adhesive systems have differentiated: From E2 glue 1970s to E1 glue, which is now standard and on to the E1 - Half - glues, on request from IKEA and because of environmental regulations in California (CARB ) have been developed. Another trend is the development of low-density wood materials. These here is the patented by BASF concept of Kaurit Light ( r ) plates: In the middle layer of particleboard wood is replaced by EPS ( Styrofoam ). The weight saving of up to 30 %, wherein both glue and wood can be saved. Nolte wood material has made the first manufacturer such chipboard under the name AirMaxx (R). AirMaxx materials are used in the kitchen industry ( Countertops ), but also in the exhibition and shop as well as in shipbuilding.
Since the last few years as fuel increases greatly the production of wood pellets, arise competing uses for wood products industry, which uses about three-quarters of sawdust from sawmills, for example, for the chipboard industry.
Characteristics and classification
The classification of particle board according to DIN EN 312-1, distinguishing between strength and moisture resistance (formerly V 20, V 100 and V 100 G).
All wood materials must have a CE mark to certify, that they emit no more than 0,124 mg Formaldehyd/m3. The content of the pesticide pentachlorophenol ( PCP) may not exceed five ppm. The fire class D -s2, d0 means that the plate is normal flammability (D ) and a mean smoking history ( s2) when burning has. However, it may be used by the burning plate no particles fall (d0 ). Should a plate be fitted with wood preservatives, must type, quantity and installation methods be noted in the CE mark.
The term " flat pressing plate " derives from the production method, the flat- pressing process. In this method, the chips are aligned in the direction of the plate plane. In the other group, the chambers pressed in from the edges of extruded plates ES (full plates) and ET ( with tubes ), the chips are oriented perpendicular to the plane of the plate. They are thus less rigid and are used for cladding and door panels.
Flat pressure plates are impact-resistant and wind- thrown, which in the production of a gradual transition from the grobspanigen middle class to the fine top layer is attained. The density is about 660 kg/m3. Single-ply consist of a homogeneous layer, three-layer and multi-layer boards of several layers, the middle layer coarse and the outer layers become finer and finer.
The following values apply to boards of Standard Types V20 and V100:
Chipboard is made for cost reasons mainly of wood residues ( coproducts, wood processing ), thinnings and increasingly used wood. Furthermore, adhesives ( glues and cement milk) used to connect the chips and various network and release agents for the pressing operation. During the manufacturing process fungicide and fire retardant for special disk requests can be added.
As a clamping plate has a smooth surface, but at the same loads to withstand, the wood must be present in various sizes. Small parts of the surface ( outer layer ), preferably large, flat parts for the core ( middle layer). For the surface of sawdust and shavings are often used. For the shredding of these substances are used shredders ( refiner ) or special mills. The other chips are produced on special Zerspanermessern from full or sawmill residues. The glue is adapted to the individual types of wood.
After machining, the material is dried, thereby, the residual moisture is reduced to about 2%. This process is flammable. Very often come drum dryer for use. These consist of a large, slightly inclined towards the exit drum which is slowly rotated about the longitudinal axis while passing through hot air. In this light, the chips move faster away than the heavy, thus a uniform drying is achieved.
The filings migrate into classifiers, where they are separated according to size, to large parts are post-processed or burned for energy.
About bunker, the chips are conveyed to the gluing and then pressed. It almost only continuous presses are used that produce an "infinite " plate that is cut at the end to the correct length.
Such a press is up to 70 m long and consists of two endless steel belts ( top and bottom ), two heated press plates, the roll bars, the pressure cylinders, the heating system and a remote heating system. The roll bars extend over the entire pressure plate width, sides, held by chains and taken away from them. They are located between the static pressure plate and the moving steel strip. The roll bars reduce friction between the heating plate and steel band and guarantee the transfer of heat. Cylinder and heating system are divided into longitudinal regions above and below, in order to control the temperature and pressure separately can. Cross each multiple cylinders are arranged. The pressing temperature is between about 200 ° C and 250 ° C.
The chips are sprinkled on a conveyor belt by means of a wind trap is thereby ensured that the surfaces are made of the finest grit and land the biggest parts in the middle of the " cake ". In the press under pressure and heat from the added glue binding and there is the clamping plate. This is cut and trimmed to the desired length. The wide surface is usually ground down. Before sanding can still be switched between a cooling phase. The resulting dust is partly used in production for the top layer, or burned for energy.
Scattered bunkers and windthrow machine
Scheme of a particleboard press
Star cooler to cool the plates
Among the largest European manufacturers include the Austrian company Kaindl and Egger. In Germany Glunz, as part of the Portuguese Sonae Indústria is one of the largest manufacturers of particle board and wood materials. Other important suppliers are Pfleiderer, and especially for the furniture industry the company Nolte.
The main customers of particleboard is the furniture industry, followed by the construction industry for the interior. Approximately 50% of particleboard manufactured in Germany are made into furniture. In many areas of use, the clamping plate can be used equally as plywood and replaces this for cost reasons. However, where high demands are made on the strength and dimensional stability of the material, plywood is a clear advantage.
Germany is the largest producer of wood-based panels in Europe and the clamping plate is quantitatively the most important product of German engineered wood industry. 2008 7.5 million m³ of particleboard produced in Germany. Compared to last year, production fell by 6.5 %. During the same period m³ particle boards were produced in Europe 34.5 million and production decreased as consumption by 9%.