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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 wooden 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

    The chips are stored temporarily.

    Machines:
    Chip store

    Cleaning chips

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

    Machines:
    Chip cleaning line

    Pulping

    The chips are boiled and pulped into fibres.

    Machines:
    Refiner

  • Pressing

    MDF Pressing process (Illustration)

    Please select

    • Glue application in the BlowLine
    • Fibre drying and coating in a mixer

    Glue application in the BlowLine

    Glue is applied and fibres are dried in one procedure step in the BlowLine. Directly after coming out of the refiner, glue is applied evenly to the fibres and sprayed in a flash tube dryer.  

    Machines:
    BlowLine

    Drying fibres

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

    Machines:
    Dryer

    Glue application in a mixer

    The dry fibre is coated in a mixer.

    Machines:
    Dry coating

    Creating fleece

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

    Machines:
    Spreading line

    Applying fluid

    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 monitoring and steering

    Compressing / Venting

    The thickly spread fibre mat is pre-compressed with belt pre-presses.

    Machines:
    Pre-press

    Pressing

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

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

    Quality surveillance

    Quality parameteres are collected in several steps of the production process and are used to steer the line.

    Machines:
    Quality monitoring and steering

  • Commissioning

    Raw fibre boards on a pallet (Illustration)

    Board cutting

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

    Machines:
    Optimising board edger, Diagonal saw, Quality monitoring and steering

    Tools:
    Saw blade

    Cooling

    When the boards come out of the press they are still hot from the pressing process. In the star cooler they cool down to storage temperature.

    Machines:
    Star cooler

    Storing

    Conditioning boards to achieve form stability.

    Machines:
    Raw board store

    Calibrating

    The raw boards are evenly sanded to the desired end-thickness (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 trading formats.

    Machines:
    Cutting-to-size line

    Tools:
    Saw blade

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