Chipboard

from Wikipedia, the free encyclopedia
A small piece of flat pressed board
The cross-section of a 16 mm thick flat pressed board
The surface of a flat pressed board
µCT flight through a piece of chipboard, side view. Resolution 44.5 µm / voxel
µCT flight through the same piece of chipboard, view from above
µCT flight through the same piece of chipboard, view from above, colored

Chipboard is made from small pieces of wood (chips) and binding agents (DIN EN 309). Depending on the orientation and size of the chips, a distinction is made between long press chipboard ( OSB ), flat press boards (P1 - P7, formerly FPY) and extruded boards (ES and ET).

Flat pressed panels are the largest and best-known subgroup of chipboard and wood chipboard as a whole. They consist of glue-coated chips of different sizes, which are usually pressed in three to five layers to form multilayer boards. The outer layers almost always consist of the finer chip material, especially if they are then coated for decorative purposes (for example in furniture construction). Since the solid wood composite has been eliminated, these panels have almost the same swelling and shrinking properties in the direction of the panel plane, i.e. length and width of the panel, but also significantly lower strengths than solid wood.

history

Chipboard was invented in the 1930s by the German Max Himmelträger to increase the recycling rate of trees, which at that time was around 40 percent. Since wood waste such as wood shavings, sawdust and branches are mainly used for chipboard in addition to glue, the recycling rate is around 80 percent today.

The foundations that led to the development of the Novopan chipboard were systematically worked out since the late 1930s by Fred Fahrni (1907–1970), for which ETH Zurich later awarded him an honorary doctorate. In 1946, the first Novopan plant was established in Klingnau (Switzerland) , which was the first in the world to start industrial production of large-format, three-layer chipboard. The company Keller & Co. AG, at that time led by Jean Frick-Keller and his son Jean Frick-Stalder, took over the industrial production of the new chipboard and founded the company NOVOPAN AG. This product was introduced worldwide together with Fred Fahrni.

The manufacture of chipboard has hardly been further developed since Himmelhub. It is worth mentioning the technical development from the stack presses to the modern Contiroll systems, which have resulted in a productivity boost of around 50 percent. On the raw material side, the glue systems in particular have become more differentiated: from E2 glue of the 1970s to E1 glue, which is standard today, and on to E1 half glue, which was introduced at the request of IKEA and due to California's environmental regulations ( CARB ) have been developed in order to further reduce the exposure to formaldehyde vapors (for more details, see the article wood chip material ).

Another trend is the development of low- density wood-based materials . In the middle layer of chipboard, wood is replaced by expanded polystyrene ( Styrofoam ). The weight saving is up to 30 percent, whereby both glue and wood can be saved. Such chipboards are used in the kitchen industry (worktops), but also in trade fair and shop construction as well as in shipbuilding.

Since the production of wood pellets as fuel has been increasing rapidly for some years now , there is competition in use with the wood-based materials industry, which uses around three quarters of the sawdust from sawmills for the chipboard industry, for example.

Features and classification

The chipboard is classified according to DIN EN 312, differentiated according to strength and moisture resistance (previously V 20, V 100 and V 100 G).

general use (not load-bearing in the static sense) Generally applicable, also for structural components highly resilient for structural components
P1 for light cladding in dry areas P4 dry area P6 dry area
P2 for furniture and interior fittings in dry areas    
P3 in the wet area P5 wet area P7 wet area

All wood-based materials must have a CE mark , which certifies that they do not emit more than 0.124 mg / m³ formaldehyde . The pentachlorophenol (PCP) content of the pesticide must not exceed 5 ppm. The fire protection class D-s2, d0 means that the panel is normally flammable (D) and that it produces medium smoke (s2) when it burns. However, no particles may fall off the burning plate (d0). If a board is equipped with wood preservatives, the type, quantity and method of application must be noted in the CE mark.

The term "flat press plate" is derived from the manufacturing method, the flat press process. In this process, the chips are aligned in the direction of the plane of the plate. In the other group, the extruded sheets ES (solid sheets) and ET (with tubes) pressed in chambers by the edges , the chips are aligned perpendicular to the plane of the sheet. As a result, they are less rigid and are used for panels and door panels.

Flat pressed panels are thrown and wind-poured, whereby a gradual transition from the coarse-chiped middle layer to the fine top layer is achieved during production. The bulk density is about 660 kg / m³. Single-layer panels consist of a homogeneous layer, three-layer and multi-layer panels consist of several layers, with the middle layer becoming coarse and the outer layers becoming finer and finer.

Technical key figures

The following values ​​apply to panels of the standard types V 20 and V 100:

properties Panel thickness in mm
until 13 > 13-20 > 20-25 > 25-32 > 32-40
Gross density (kg / m³) 750-680 720-620 700-600 680-580 650-550
Flexural strength flat (N / mm²) 25-18 22-16 20-15 18-13 15-12
Flexural modulus of elasticity, flat (N / mm²) 4500-3200 4000-2800 3500-2500 3000-2000 2500-1600
Flexural modulus upright (N / mm²) 2200 1900 1600 1300 1000
Flexural strength upright (N / mm²) 18-13 15-12 13-11 12-10 11-9
Tensile strength in plane of the plate (N / mm²) 10-8 10-8 9-7 9-7 8-6
Tensile modulus in the plane of the plate (N / mm²) 3000-2500 2800-2300 2700-2200 2600-2100 2500-1900
Compressive strength in the plane of the plate (N / mm²) 15-13 15-13 14-12 14-12 13-11
Compression modulus in the plane of the plate (N / mm²) 3000-2500 2800-2300 2700-2200 2600-2100 2500-1900
Transverse tensile strength dry (N / mm²) 1.0-0.5 0.8-0.4 0.7-0.35 0.6-0.3 0.5-0.25
Block shear strength (N / mm²) 2.8-1.4 2.2-1.1 2.0-1.0 1.0-0.9 1.4-0.7
Shear strength perpendicular to the plane of the plate (N / mm²) 10-7 9-6 9-6 8-5 8-5
Lift-off strength (N / mm²) 1.6-0.8 1.6-0.8 1.6-0.8 1.6-0.8 1.6-0.8
Brinell hardness 50-40 45-35 45-35 40-30 40-30

Commercially available dimensions

Thickness: 8, 9, 10, 12, 13, 14, 15, 16, 18, 19, 22, 24, 25, 28, 32, 35, 38 and 40 mm, extra thin from 2.5 mm (then also thin chipboard called) and extra thick up to 80 mm.
Format: up to 6700 × 2500 mm or, in the thin chipboard area, the endless plate wound as a coil up to 100 meters long.
Tongue and groove: 2050 × 925 mm (covering dimensions 2040 × 915 mm) and 2050 × 615 mm (covering dimensions 2040 × 605 mm).

Manufacturing

For cost reasons, chipboard is mainly made from wood residues (by- products of woodworking and processing), thinning wood and increasingly also used wood. Furthermore, adhesives (wood glue and cement milk) are used to connect the chips and various wetting and separating agents for the pressing process. During the manufacturing process, anti-fungal and fire retardants can be added for special panel requirements.

Wood processing

In order for a chipboard to have the smoothest possible surface and at the same time withstand loads, the wood must be available in different sizes: small parts for the surface (top layer) and the largest possible flat parts for the core (middle layer). Sawdust and wood shavings are often used for the surface. Refiners or special mills are used to shred these materials . The other chips are produced on special chipper knives from solid or saw residue. The glue is matched to the individual types of wood.

dryer

After machining, the material is dried and the residual moisture is reduced to around 2 percent. This process is flammable. Drum dryers are used very often. These consist of a large drum, slightly inclined towards the exit, which rotates slowly around its longitudinal axis and through which hot air flows. In this, the light chips move faster than the heavy ones, which means that even drying is achieved.

The chips then move into separators, in which they are separated according to size; Parts that are too large are reprocessed or burned to generate energy.

Grouting

The chips are conveyed via bunkers for gluing and then pressed. Almost only continuous presses are used, which produce an “infinite” panel that is cut to the correct length at the end.

Such a press is up to 70 meters long and consists of two endless steel belts (top and bottom), two heated press plates, the roller bars, the press cylinders, the heating system and a counter heater. The roller bars extend over the entire width of the press plate, are held at the sides by chains and are taken along by them. They are located between the static press plate and the moving steel belt. The roller bars reduce the friction between the heating plate and the steel belt and guarantee heat transfer. The cylinder and heating system are divided into longitudinal areas at the top and bottom so that temperature and pressure can be controlled separately. Several cylinders are arranged transversely. The pressing temperature is approximately between 200 ° C and 250 ° C.

The shavings are scattered on a conveyor belt, and a wind-throwing machine ensures that the surfaces consist of the finest grit and that the largest pieces end up in the middle of the "cake". In the press, the added glue sets under pressure and heat and the chipboard is created. This is sawn and trimmed to the required length . The broad surface is usually ground. A cooling phase can be included before the grinding. Some of the dust produced is used in production for the top layer, otherwise it is burned to generate energy.

  • How the windthrow machine works

  • Litter bunker and wind throwing machine

  • Scheme of a particle board press

  • Star turner to cool the plates

Manufacturer and consumption

The Austrian companies Egger and Kaindl are among the largest European manufacturers . In Germany, Sonae Arauco Deutschland GmbH is one of the largest manufacturers of chipboard and wood-based materials. Other important suppliers are Pfleiderer GmbH and especially for the furniture industry the company Nolte .

Germany is the largest manufacturer of wood-based materials in Europe and, in terms of quantity, chipboard is the most important product in the German wood-based materials industry. In 2008, 7.5 million m³ of chipboard were produced in Germany. In the same period, 34.5 million m³ of chipboard were produced across Europe.

Use and disposal

The main buyer of chipboard is the furniture industry, followed by the construction industry for interior fittings. About 50 percent of the chipboard manufactured in Germany is made into furniture.

The chipboard is getting more and more competition from the cheap MDF board .

In Switzerland, chipboard can be handed over to the waste collection as bulky goods, provided that the respective waste association so provides, otherwise it must be returned to the local bulky goods collection point. In Germany, furniture made from chipboard can be disposed of with bulky waste.

See also

literature

  • Hans-Joachim Deppe, Kurt Ernst: Pocket book of particle board technology . 4th, revised and expanded edition. DRW, Leinfelden-Echterdingen 2000. ISBN 3-87181-349-4 .
  • Karl-Reinhard Volz : Investigation of the properties of the bark of spruce, pine and beech and its suitability as a raw material for flat pressed panels . In: WKI report , No. 3. Wilhelm Klauditz Institute for Wood Research, Braunschweig 1974.
  • Manfred Dunky, Peter Niemz: Wood-based materials and glues . Technology and influencing factors. Springer, Berlin / Heidelberg / New York / Barcelona / Hong Kong / London / Milan / Paris / Tokyo 2002, ISBN 3-540-42980-8 .
  • Peter Niemz, André Wagenführ: Materials made of wood. In: André Wagenführ, Frieder Scholz: Taschenbuch der Holztechnik. Fachbuchverlag Leipzig in Carl-Hanser-Verlag, Munich 2008. ISBN 978-3-446-22852-8 . Pp. 127-259.

Web links

Commons : Particle board  album with pictures, videos and audio files
Wiktionary: Chipboard  - Explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Press release in May 2009
  2. ↑ European Association of Wood-Based Materials (EPF) and Association of the German Wood-Based Panels Industry (VHI). Holz-Zentralblatt May 13, 2009 and May 14, 2009
  3. ↑ WPC boom in spite of the Europe-wide slowdown in wood-based materials - wood-plastic composites in Germany with 78% increase in production. In: Bio-Based News. May 14, 2009, from News.bio-based.eu, accessed on February 12, 2017.
  4. ↑ Example Dübendorf: City of Dübendorf: Bulky goods