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MDF board (Illustration)

Production process

Fibre boards (MDF/HDF)

Fibre boards have a homogenous structure that is finer than with chip board. Thus they can be processed similarly to solid wood. For example, it is possible to mill them and fit them with profiles. One differentiates mainly between MDF (medium dense fibre board) and HDF (highly dense fibre board). The most modern are the especially thin fibre boards from 1 mm thickness (THDF and UT-HDF).

The medium density fibre board (MDF) was invented in the USA and became more common in Europe towards the end of the 1980s. MDF is mainly used in the furniture and flooring industry, as well as in interior construction. Other applications are, among others, for doors, as interior covers in the automotive industry, in construction, or in semiconductors. The boards can be veneered, laminated, laquered, or coated. Boards are produced from 1.2 mm to 60 mm. The density ranges from 600 kg/ m³    to 1200 kg/ m³. The boards with  a density over 800 kg/m³     are usually known by the name HDF. These are mainly used as beams for the flooring industry (Laminate flooring). In total, around 100 million  m³    (2016) MDF/HDF boards are produced. The largest capacities are in China, Turkey and Brazil. 

Source product

The base material for MDF and fibre boards are woodcontaining fibres. Mainly the materials used are industrial logs, saw side products (wood chips), rarely also scrap wood. It is also possible to use bamboo, bagasse, rice and wheat straw, or similar vegetable fibres. In the procedure described here, we are assuming industrial logs are the raw material basis. Deviations from the production process can be possbile if the raw material is different. 

Production Process

  • Fibre preparation

    Wood fibres for MDF production (Illustration)

    Debarking

    The trunks are debarked in drum or rotor debarkers.

    Machines:
    Debarking line

    Tools:
    Knife

    Chopping

    Uniform chips are created out of the debarked logs in a chopping line. When using recycling wood, foreign objects, or resp., interfering components have to be removed.

    Machines:
    Chopper

    Tools:
    Knife

    Storing chips

    Chips are temporarily stored.

    Machines:
    Chips store

    Cleaning chips

    The chips cleaning process cleans the goods of foreign objects, such as stones and sand. 

    Machines:
    Chips cleaning

    Pulping

    The chips are boiled and ground to fibres.

    Machines:
    Refiner

  • Pressing

    MDF Press process (Illustration)

    Please select

    • Glue application in the BlowLine
    • Drying the fibres and applying glue in the mixer

    Glue application in the BlowLine

    In the Blowline, glue is applied and the fibres are dried in one step. Directly after leaving the refiner, the fibres are coated evenly with the glue and sprayed in a flash tube dryer. 

    Machines:
    blending and drying

    Fibre drying

    Wood fibres for MDF production require a drying process with extremely short holding times in the drying tube. Fibre dryers therefore work according to the flash tube dryer principle.

    Glue application in a mixer

    The dry fibre is coated in a mixer.

    Machines:
    Dry coating

    Creating fleece

    The coated fibres are evenly spread out on a continuously running conveyor belt.

    Machines:
    Spreading line

    Fluid application

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

    Machines:
    Spray device

    Surface weight measurement

    Quality parameters are collected in diverse positions during production and used to steer the line.

    Machines:
    Quality surveillance and steering

    Compressing / Venting

    The thickly spread fibre mat is pre-pressed using belt pre-presses.

    Machines:
    Mat press, Mat pre-heating

    Pressing

    In the heat press the board is given its later thickness and structure. On the one hand the glue sets; on the other hand the wood is also plastified and permanently shaped.

    Machines:
    Continuous press, Multi-layer press, One-layer press

    Quality surveillance

    At different points during production quality parameters are collected and used to steer the line. 

    Machines:
    Quality surveillance and steering

  • Finish raw board

    finished raw fibre board (Illustration)

    Pre-formatting

    After the press, the endless board is edged and cut to length. The diagonal saw that is synchronised with the press speed cuts the board to a predetermined length. 

    Cooling

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

    Calibrating

    The raw boards are evenly sanded to the desired end thickness (calibrated).

  • Coating

    Coated fibre board (Illustration)

    Coating

    The boards can be coated with a decorative surface, or be varnished to raise their value.

    See also process Flooring/Laminate flooring.

    Machines:
    Short-cycle press, Feeding the materials, Varnishing

  • Commissioning

    Coated fibre boards, layered and bound (Illustration)

    Formatting

    The boards are cut into smaller final formats in a cutting line. 

    Machines:
    Cutting-to-size line

    Tools:
    Saw blade

    Conveying, storing and packaging

    The board formats are stacked, conveyed and packaged and therefore ready for shipping.

Production process:Fibre boards (MDF/HDF) – Procedure in individual steps – Coated MDF board

Necessary peripheral devices for Fibre boards (MDF/HDF)5

  • Cranes for roundwood yards

    E.g. used in:Chip board, Fibre boards (MDF/HDF), 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

  • 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

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