Medium density fibreboard panels have a smooth wood-grain finish and are often used in combination with other materials, such as plywood.
Made from wood pulp and resin, Medium Density Fibreboard (MDF) is a tough, strong, and moisture resistant material with many uses in construction, joinery, decorative home projects, and furniture making.
The production process for MDF wood involves pulp being mixed with water and then heat is applied to the mix. This causes the natural wood fibres to separate from each other and become extremely fine. The resulting material is then pressed into sheets at high temperatures and under intense pressure. It finally goes through a cooling tower, where it comes out ready for cutting or joining.
MDF can be cut using power saws or knives, but small pieces should be cut using blades designed specifically for cutting MDF because they make much finer kerf (cut width). Saw blades should always be very sharp and when cutting MDF it is crucial to have a good dust extraction system because it tends to have a large number of particles in the air.MDF can be made from softwood residuals or hardwood fibre. Finished board thickness is measured in density. Due to the different characteristics of materials, a thick MDF panel made of softwood fibre rated at the same density as that of hardwood fibre is significantly different.
The surface quality depends on how well the board has been machined after manufacture, so final sanding is also an important factor in achieving a high standard finish.
Resin-type wood fillers are usually required to close up any defects or irregularities in panels composed of natural wood fibres that are not perfectly aligned. The tiny spaces left between them may result in uneven moisture absorption and therefore changing dimensions after installation.
MDF is made using heat and pressure to compress wood pulp into sheets. The main raw materials used are sawdust, wood shavings, and ground-up wood scraps, in addition to either natural or synthetic urea-formaldehyde resin binder. The process of manufacturing medium density fibreboard typically involves the following steps:
Pulp is mixed with water in a large vat to form a wet slurry. The exact composition of the pulp varies depending on whether it will be used for structural or decorative MDF panels but typically contains sawdust, wood chips/shavings, cellulose fibres (wood pulp), synthetic resin binder, and an optional co-solvent.
The slurry then undergoes primary screening to remove any oversized particles that would later negatively affect its strength and dimensional stability during production or hinder performance at high temperatures.
All the remaining lightweight fibre materials are transferred into vacuum forming equipment. They are repeatedly sucked through nozzles while being heated up under pressure, which causes them to expand significantly before being cooled again.
The flow of slurry is then directed into a water tank where it is mixed with preservatives, lubricants, wax. The synthetic resin binder is added as the main bonding agent in order to enhance MDF's binding properties. Wax improves the moisture resistance of the MDF. The sheet forming dry fibre is fed into a pendistor. This machine evenly distributes fibre into a uniform mat right below it.
After the hot press compression under extreme heat in a final heated expansion chamber, the boards are left overnight to dry before being cut into smaller pieces during secondary screening in preparation for gluing. This is typically done on power saws for structural MDF panels, but only knives are used in decorative MDF manufacturing because there is no need to speed up the process.
The panels are then sent through a cooling tower, where they come out ready for cutting or joining.
The answer to this question is quite complicated because it depends on the specific requirements of the manufacturer. As a building material, MDF has many benefits over natural wood, including being low-cost, lighter, dimensionally stable, having a very smooth surface, and very easy to work with, but only when used in place of solid wood for structural purposes.
Also, when compared to other manufactured wood products, it is stronger than a particle board product. MDF is also generally denser (a high density board) than plywood and does not have exposed edges when sawed down, as is the case with plywood.
While MDF can be glued using conventional adhesives without any problems, specialist equipment is needed for edge gluing boards into sheets that are then cut into smaller pieces. Natural wood components have better mechanical properties than MDF, especially if laminated or veneered/veneer bonded for additional strength. This makes them more suitable for certain decorative applications such as cabinetry and furniture manufacture, where dimensional accuracy is very important.
The weight of natural wood is typically 15-20 kg per cubic metre, but MDF panels are available in thicknesses ranging from 4 to 40 mm with a corresponding bulk density of only 0.5-0.7 kg/L depending on the specific production process and raw materials used.
This makes it significantly easier to transport, handle and install decorative MDF components that weigh several tonnes compared to solid timber or veneered engineered board products, which usually have densities two orders of magnitude higher.
High-density MDF boards can also be left unfinished without any problems because they are naturally resistant to moisture, insects, and mould growth, unlike natural wood-based products that need an additional protective coating to prevent them from degrading over time.
Softwood fibre panels rated at the same density as hardwood boards will have a lower mechanical strength.
While laminated components tend to be much more expensive than MDF boards that are glued together, they can be much thicker without adding any extra weight because of their superior strength and stiffness, especially if hardwood veneers that have undergone a kiln drying process or particleboard fibres with resin fillets around them called 'fibre reinforced panels' (FRP) are used instead of paper and/or cardboard discs. These panels can also withstand temperatures up to 140 °C without risking combust or substantial warping.
Many of these products also have a significantly reduced need for re-treatment in comparison to bare natural wood components, which tend to warp and split over time unless regularly treated with wooden oil or an environmentally friendly water-based product.
In general, MDF board panels are perfectly suitable for interior applications by carpenters or woodworkers. They benefit from better dimensional stability when exposed to ambient conditions because of the lack of moisture in the air compared to natural wood that can expand and contract considerably under different humidity levels. The surface hardness and wear resistance is also much higher on high-density MDF boards used in all types of construction, including flooring, wall cladding, staircases, kitchen worktops, and furniture manufacturing.Natural wood components have significantly superior mechanical properties than MDF boards, especially when it comes to strength and hardness. This makes them more suitable for certain exterior applications such as staircases, kitchen worktops, and furniture manufacturing, where they are resistant to mould growth, warping, insects, and lasting moisture absorption.
There have been health concerns about the safety of MDF, especially the urea-formaldehyde emissions released into the air from disintegrating MDF board.
There are certifications issued by various global bodies to address these concerns. These include those guidelines issued by the Californian air resources board. The European formaldehyde classes have 2 main categories (E1 and E2) relating to formaldehyde release. E1 boards should release less than 0.1 parts per million of formaldehyde and E2, between 0.1 to 0.3
The risks associated with exposure to MDF's urea-formaldehyde dust particles are similar to those related to inhaling wood dust if the product meets the EU's E1 standards. SafeWork New South Wales has a handy guide to the hazards of wood dust from materials such as MDF.