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OSB board (Illustration)

Production process

OSB- Oriented Strand Board

OSB boards (Oriented Strand Boards) are wood composite material produced out of long, thin chips, so-called strands. OSB is used as building boards in structural work (e.g. roof plating) and in interior construction as walls. In flooring it is used as laying boards (slot-and-groove profile). For visual floors, in attic conversions, and as a facade it is used as a decorative element thanks to its chiselled look, also in furniture production for shelves and racks. Furthermore it is used for packaging (chests, cable drums, paletts), store and fair construction, construction site fences, and as concrete shell boards. Several OSBs glued together can function as wall and ceiling elements in timber house construction. 

OSB is one of the 'Engineered wood products' which were developed in the 50s in the USA and Canada. Their goal was to create a board with almost the same technical features as plywood, but using sufficiently available, quickly growing wood material, with a small trunk diameter. They deliberately used long, thin strands in production, that were layered oriented and pressed. Classic OSB consists of 3 layers. The cover layer chips oriented in production direction maximise the board's bending strength.

In total the global production capacity for OSB makes up about 40 million m³. The largest capacities are in the USA, Canada, and Europe (especially in Germany and Romania). Countless new plants have started to work in Russia recently. Asia has also seen a break-through: In the meantime there are countless plants in China and South-East Asia. 

Source product

Logs are the optimum raw material for OSB production. Mainly fresh wood is used to produce the strands to ensure their high elasticity. Dry wood on the other hand is brittle and results in too much fine material during chipping. 

Production Process

  • Strand preparation

    Strands for OSB production (Illustration)

    Debarking

    The higher the amount of bark, the more the finished board's stability is decreased and there is a negative influence on the wood-typical swelling and shrinking behaviour. Therefore, it is absolutely necessary to debark the logs. Furthermore, debarking also makes the OSB board's surface look optically better.

    Machines:
    Debarking line

    Tools:
    Knife

    Machining

    To achieve as high a board quality as possible, the strands should only have few variations in thickness, length, width, and proportion of fine material. Special knife ring flakers, also known as stranders, are used in production.

    Machines:
    Knife ring flaker, Blade grinding machine

    Tools:
    Knife

    Drying

    The strands are continuously fed into the dryers from the wet chip silos. The necesary energy for drying  is usually provided by a hot gas generator. 

    Machines:
    Dryer, Hot gas generator

    Measuring moisture

    Quality parameters are collected at different points during production and used to steer the line. These include, among others, moisture, density, or thickness of the chips or the finished board after pressing. 

    Machines:
    Moisture measuring device

    Sorting / Sieving

    The strands are sieved and sorted according to their geometry to be used in the middle or cover layer. Usually drum sieves are used for this.

    Machines:
    Drum sieve

  • Pressing

    Press process in OSB production (Illustration)

    Coating

    The strands are fed into the coating machine via belt scales. These ensure that the right amount of strands is available for the respective production performance and at the same time that the coating degree is adhered to. 

    Machines:
    Facility for glue preparation and dosage, Weighing line

    Mixing

    The strands are circulated in large volume mixers. Atomisers (also: Rotation sprayer, vaporiser) spray glue, paraffin, hardener, and water finely and simultaneously.

    Machines:
    Mixer

    Spreading

    The strands are fed by the delivering and distributing rollers to the spreading heads. The cover layers are oriented in production direction, the middle layer at a right angle to them. Both the weight of the spread mat, as well as the proportion of the cover layers to middle layer, are permanently controlled by scales.

    Machines:
    Spreading machine

    Applying fluid

    Water, release agents, and other additives can be sprayed on prior to pressing.

    Machines:
    Spray device

    Pre-pressing

    To ensure a high board quality it is possible to vent the spread chip mat before putting it into the press. This is done by belt pre-presses that pre-compress the partially very thickly spread mats using pressure. It is also possible to pre-heat the mat to raise production capacity.

    Machines:
    Mat press

    Pressing

    In the press the glue is hardened by pressure and temperature and the mat is pressed to the required thickness. Mainly two types of presses are used in OSB production: multi-layer presses and continuous presses. In recent years the continuous presses have become more and more popular. The advantages of this press type are its high performance level, as well as the lack of idle time (in comparison to multi-layer presses), so that it is possible to achieve a high amount of thin boards (6 to 12 mm), too.

    Machines:
    continuous press, Multi-layer press

  • Commissioning

    OSB board stack on a pallet, bound (Illustration)

    Board sizing

    After leaving the press the board is cut to the desired length and width.

    Machines:
    Optimising board edger, Diagonal saw, Quality surveillance and control

    Tools:
    Saw blade

    Cooling

    When the boards leave the press they are still hot from pressing. In the star cooler they cool down to storage temperature.

    Machines:
    Star cooler

    Sanding

    OSB boards that require an exact thickness tolerance are fed into the sanding line and sanded there (calibrated).

    Machines:
    Sanding machine

    Tools:
    Wide-belt

    Formatting

    In a cutting line or cutting-to-size line the finished raw boards are cut into the smaller trade formats.

    Machines:
    Cutting-to-size line

    Tools:
    Saw blade

Production process:OSB- Oriented Strand Board – Process in individual steps

Necessary peripheral devices for OSB- Oriented Strand Board10

  • Boiler systems with furnaces for wood fuels (solid wood, chips, dust, etc.)

    E.g. used in:Chip board, OSB- Oriented Strand Board

  • Cranes for roundwood yards

    E.g. used in:Chip board, Fibre boards (MDF/HDF), OSB- Oriented Strand Board

  • Explosion protection systems

    E.g. used in:Chip board, OSB- Oriented Strand Board

  • Fire and spark extinguishing systems

    E.g. used in:Furniture front, Windows, Flooring, Wooden stairs, Chip board, OSB- Oriented Strand Board

  • Log sorting stations

    E.g. used in:Chip board, Fibre boards (MDF/HDF), OSB- Oriented Strand Board

  • Mobile log conveyors

    E.g. used in:Chip board, Fibre boards (MDF/HDF), OSB- Oriented Strand Board

  • Plants, units and auxiliary equipment for energy generation; other

    E.g. used in:Chip board, OSB- Oriented Strand Board

  • Stationary conveying devices for roundwood yards

    E.g. used in:Chip board, Fibre boards (MDF/HDF), OSB- Oriented Strand Board

  • Storage systems for roundwood yards

    E.g. used in:Chip board, Fibre boards (MDF/HDF), OSB- Oriented Strand Board

  • Wood furnaces for generating hot gas

    E.g. used in:Chip board, OSB- Oriented Strand Board

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