Medium-density fiberboard (
MDF) is an
engineered woodEngineered wood, also called composite wood, man-made wood includes a range of derivative wood products which are manufactured by binding together the strands, particles, fibers, or veneers of wood, together with adhesives, to form composite materials. These products are engineered to precise...
product formed by breaking down hardwood or softwood residuals into
woodWood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of trees . In a living tree it transfers water and nutrients to the leaves and other growing tissues, and has a support function, enabling woody plants to reach large sizes or to stand up for themselves...
fibres, often in a
defibratorThe defibrator is a thermo mechanical pulping refiner in which the pulp material, such as wood chips, is ground in an environment of steam between a rotating grinding disc and a stationary disc each with radial grooves that provides the grinding surface...
, combining it with
waxWax refers to beeswax or another substance with similar properties. The traditional meaning, beeswax, refers to a substance secreted by bees and used by them in constructing their honeycombs...
and a
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
binder, and forming panels by applying high
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
and
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
.
It is made up of separated fibers, (not
wood veneerIn woodworking, veneer refers to thin slices of wood, usually thinner than 3 mm , that are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry...
s) but can be used as a building material similar in application to
plywoodPlywoodis a type of engineered wood made from thin sheets of wood, called plies or wood veneers. The layers are glued together so that adjacent plies have their grain at right angles to each other for greater strength. There are usually an odd number of plies, as the symmetry makes the board less...
. It is much more dense than normal
particle boardParticle board, or particleboard, is an engineered wood product manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extruded...
.
The name derives from the distinction in
densitiesThe density of a material is defined as its mass per unit volume. The symbol of density is ρ .- Formula :Mathematically:where: is the density, is the mass, is the volume....
of
fiberboardFiberboard is a type of engineered wood product that is made out of wood fibers. Types of fiberboard include particle board, medium-density fiberboard, and hardboard. Fiberboard is sometimes used as a synonym for particle board, but particle board usually refers to low-density fiberboard...
.
Medium-density fiberboard (
MDF) is an
engineered woodEngineered wood, also called composite wood, man-made wood includes a range of derivative wood products which are manufactured by binding together the strands, particles, fibers, or veneers of wood, together with adhesives, to form composite materials. These products are engineered to precise...
product formed by breaking down hardwood or softwood residuals into
woodWood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of trees . In a living tree it transfers water and nutrients to the leaves and other growing tissues, and has a support function, enabling woody plants to reach large sizes or to stand up for themselves...
fibres, often in a
defibratorThe defibrator is a thermo mechanical pulping refiner in which the pulp material, such as wood chips, is ground in an environment of steam between a rotating grinding disc and a stationary disc each with radial grooves that provides the grinding surface...
, combining it with
waxWax refers to beeswax or another substance with similar properties. The traditional meaning, beeswax, refers to a substance secreted by bees and used by them in constructing their honeycombs...
and a
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
binder, and forming panels by applying high
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
and
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
.
It is made up of separated fibers, (not
wood veneerIn woodworking, veneer refers to thin slices of wood, usually thinner than 3 mm , that are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry...
s) but can be used as a building material similar in application to
plywoodPlywoodis a type of engineered wood made from thin sheets of wood, called plies or wood veneers. The layers are glued together so that adjacent plies have their grain at right angles to each other for greater strength. There are usually an odd number of plies, as the symmetry makes the board less...
. It is much more dense than normal
particle boardParticle board, or particleboard, is an engineered wood product manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extruded...
.
The name derives from the distinction in
densitiesThe density of a material is defined as its mass per unit volume. The symbol of density is ρ .- Formula :Mathematically:where: is the density, is the mass, is the volume....
of
fiberboardFiberboard is a type of engineered wood product that is made out of wood fibers. Types of fiberboard include particle board, medium-density fiberboard, and hardboard. Fiberboard is sometimes used as a synonym for particle board, but particle board usually refers to low-density fiberboard...
. Large-scale production of MDF began in the 1980s.
Types of MDF
There are different kinds of MDF, which are sometimes labeled by colour:
- Moisture resistant is typically green
- Fire retardant
A fire retardant is a substance that helps delay or prevent combustion. Fire retardants are commonly used in fire fighting. Water is the most commonly used fire retardant, but the phrase typically refers to chemical retardants, including fire-fighting foams and fire-retardant gels...
MDF is typically red or pink
Although similar manufacturing processes are used in making all types of fiberboard, MDF has a typical density of 600-800 kg/m³ or .022-.029 lbs/in
3, in contrast to particle board (160-450 kg/m³) and to
high-density fiberboardHardboard, also called high-density fiberboard, is a type of fiberboard, which is an engineered wood product. It is similar to particleboard and medium-density fiberboard, but is denser and much stronger and harder because it is made out of exploded wood fibers that have been highly compressed....
(600-1450 kg/m³).
Another addition to the MDF range is a product named FX-Platform, produced by
NorbordNorbord Inc. is an international forest products company headquartered in Toronto, Ontario. It has 15 operations located in Canada, the United States and Europe, with assets of US$ 1.4 billion and annual sales in excess of $1 billion...
. It is a softwood plywood core, laminated on both sides with MDF, giving it working properties containing the advantages of both plywood and MDF. This product has met the acceptance criteria for compliance with the ANSI/HPVA HP-1-2004 Section 3.12 Formaldehyde Emission Requirements for industrial panels.
Lighter densities of fiberboard are commonly marketed as ultralight or LDF boards.
Manufacture
In
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
the main species of tree used for MDF is
plantationA plantation is a large farm or estate, usually in a tropical or subtropical country, where crops are grown for sale in distant markets, rather than for local consumption. The term plantation is informal and not precisely defined....
-grown radiata pine but a variety of other products have also been used including other woods, waste paper and fibers.
The trees are debarked after being cut. The bark can be sold for use in
landscapingLandscaping refers to any activity that modifies the visible features of an area of land, including:# living elements, such as flora or fauna; or what is commonly referred to as gardening, the art and craft of growing plants with a goal of creating a beautiful environment within the landscape.#...
, or burned in on-site furnaces. The debarked logs are sent to the MDF plant where they go through the
chippingA tree chipper or wood chipper is a machine used for reducing wood into smaller parts, such as wood chips or sawdust. They are often portable, being mounted on wheels on frames suitable for towing behind a truck or van...
process. A typical disk chipper contains 4-16 blades. Any resulting chips that are too large may be re-chipped; undersized chips may be used as fuel. The chips are then washed and checked for defects.
The chips are then compacted using a screw feeder, and will be heated for 30-120 seconds to soften the wood; they are then fed into a
defibratorThe defibrator is a thermo mechanical pulping refiner in which the pulp material, such as wood chips, is ground in an environment of steam between a rotating grinding disc and a stationary disc each with radial grooves that provides the grinding surface...
which maintains high pressure and temperature. The
pulpPulp is a dry fibrous material prepared by chemically or mechanically separating fibers from wood, fiber crops or waste paper.Pulp can be either fluffy or formed into thick sheets. The latter form is used if the pulp must be transported from the pulp mill to a paper mill...
that exits from the defibrator is fine, fluffy, and light in weight and in colour.
From the defibrator the pulp enters a blowline where it is joined with wax (to improve moisture resistance) and resin (to stop the pulp from forming bundles). The material expands in size and is then heated by heating coils. When it comes out it may be stored in bins for an indefinite length of time.
After this drying period the board goes through a "Pendistor" process which creates 230-610 mm thick boards. Then it is cut and continues to the press. Here it is pressed for a few minutes, to make a stronger and denser board.
After pressing MDF is cooled in a star dryer, trimmed and sanded. In certain applications, boards are also
laminatedLamination paper is a paper used for laminates. Normally on particle or fiberboards giving a good-looking and resistant surface for use as furniture, decoration panels and flooring..-Properties:...
for extra strength.
The Environmental Impact of MDF has greatly improved over the years. Today many MDF boards are made from a variety of materials. These include other woods, scrap, recycled paper, bamboo, carbon fibers and polymers, steel, glass, forest thinning and sawmill off-cuts.
As manufacturers are being pressured to come up with greener products, they have started testing and using non-toxic binders. New raw materials are being introduced.
StrawStraw is an agricultural by-product, the dry stalk of a cereal plant, after the grain or seed has been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat...
and
bambooThe bamboos are a group of woody perennial evergreen plants in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Some are giant bamboos, the largest members of the grass family. Bamboos are the fastest growing woody plants in the world...
are becoming popular fibers because they are a fast growing renewable resource.
Comparison to natural woods
Benefits of MDF:
- Is an excellent substrate for veneers
In woodworking, veneer refers to thin slices of wood, usually thinner than 3 mm , that are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry...
.
- Is becoming an environmentally friendly product.
- Some varieties are less expensive than many natural woods
- Isotropic (no grain), so no tendency to split
- Consistent in strength and size
- Flexible. Can be used for curved walls or surfaces.
- Shapes well.
Drawbacks of MDF:
- Denser than plywood or chipboard (the resins are heavy)
- Swells and breaks when waterlogged
- May warp or expand if not sealed
- Contains urea-formaldehyde
Urea-formaldehyde, also known as urea-methanal, named so for its common synthesis pathway and overall structure, is a non-transparent thermosetting resin or plastic, made from urea and formaldehyde heated in the presence of a mild base such as ammonia or pyridine. These resins are used in...
which may cause eye and lung irritation when cutting and sanding
- Dulls blades more quickly than many woods
- Though it does not have a grain in the plane of the board, it does have one into the board. Screwing into the edge of a board will generally cause it to split in a fashion similar to delaminating.
- Subject to significant shrinkage in low humidity environments.
- Trim (i.e. baseboards) comes pre-primed but this is insufficient for fine finish painting. Painting with latex paints is difficult due to rapid water absorption. Most finishes appear uneven and nail holes tend to pucker a bit.
Recent developments
A fairly recent development is flexible MDF sheets. These are sheets scored with multiple slots so that the material can easily be formed into curved shapes and then fixed. The manufacturer is mdf fibreboard.
Applications
MDF is often used in school projects because of its flexibility.
It is also often used in
loudspeakerA loudspeaker is an electroacoustic transducer that converts an electrical signal into sound. The speaker pulses in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water.Loudspeakers are the most variable elements in a...
enclosures, due to its increased weight and rigidity over normal plywood.
SlatwallSlatwall is kind of building material.Slatwall is a panel made with horizontal grooves that are configured to accept a variety of merchandising accessories. Standard spacing of these grooves is 3” OC , but this spacing can be changed to accommodate merchandising density. Optional groove treatments...
Panels made from MDF are used in the
shop fittingShop fitting is the trade of fitting out retail and service shops and stores with equipment and merchandise. The trade applies to all kinds of outlets from a small corner shop to hypermarkets. A shop fitter executes planning, design of shop layout, and most importantly physically stocks the shop...
industry.
Safety aspects of MDF
When MDF is cut, a large quantity of dust particles is released into the air. It is important that a
respiratorA respirator is a device designed to protect the wearer from inhaling harmful dusts, fumes, vapors, and/or gases. Respirators come in a wide range of types and sizes used by the military, private industry, and the public...
be worn and the wood be cut in a controlled and ventilated environment. It is a good practice to seal the exposed edges to limit the emissions from the binders contained in this material.
FormaldehydeFormaldehyde is a chemical compound with the formula CH2O. It is the simplest aldehyde. Formaldehyde also exists as the cyclic trimer trioxane and the polymer paraformaldehyde. It exists in water as the hydrate H2C2. Aqueous solutions of formaldehyde are referred...
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
s are commonly used to bind MDF together, and testing has consistently revealed that MDF products emit formaldehyde and other volatile organic compounds that pose health risks at sufficient concentrations, for at least several months after manufacture. Whether these chronic emissions reach harmful levels in real-world environments is not yet fully determined.
External links