1. What is MDF?
Medium-density fiberboard (MDF) is a wood based panel which made from wood fiber (or wood flour) from hardwood and soft wood, adhesive and other components (Paraffin, hardener…) pressed under high temperature and pressure.
2. History and development
The first factory producing MDF was built in 1964 in New York (USA). It was not until 1990 that MDF developed in North American and European countries.
By 1970, there were only three US factories that able to produce from 39,000 m3/year to 133,000 m3/year. However, by 2000, there were a total of 291 factories worldwide and the largest factory capacity was 340,000 m3/year.
In response to market demand, industrial countries have accelerated constructing MDF factory with an annual quantity increases by15.5%. In 1996, there were 17.53 million m3 of MDF produced worldwide. By 2001, total MDF production worldwide was 29.056 million m3.
3. Components of MDF
– A MDF board is composed of wood fiber (or wood flour), adhesive and other components (paraffin, hardener …).
– MDF consists of about 75% wood, 11-14% Urea Formaldehyde (UF), 6-10% water and less than 1% other components (paraffin, hardener …). For high humidity environments, Melamine resin or Phenolic & Polymeric Diphenylmethane Diisocyanate (PMDI) is added to the glue to create a moisture-resisting MDF.
– The fibers (or wood flour) in MDF board are mainly made from softwood. However, depending on the purpose of the manufacturer, some hardwood components can be added to achieve the desired wood type.
– Raw materials to produce MDF board are planted wood (such as rubber, eucalyptus, acacia, pine, rattan, oak, spruce), bagasse, wood waste, sawdust or mixture of hard-woodchips and soft-woodchips. Besides tree trunk, inputs can also be tops, cornices, chips, sawdust of the sawing process.
4. Physical Characteristics and General Features
– MDF boards have the color of wood (yellow, brown). The color of moisture resistant boards (HMR) is green and of fire-resistant boards is red.
– MDF is stable and inert as a sheet. The board is biodegradable over time.
– Average density: 680 – 840 kg/m3.
– Standard size of MDF boards are 1220 x 2440 and 1830 x 2440 (mm).
– Typical thickness: 3, 5, 9, 12, 15, 17, 18, 25 (mm).
5. The manufacturing process MDF boards
MDF board is produced by pressing small wood fibers under high pressure and temperature with the participation of adhesives and other components.
There are two MDF board production processes: dry and wet process.
a. Dry process
– First, adhesive and additives are sprayed onto the dry wood flour in the mixer and preliminary dried.
– After the adhesive is dried, the fiber will be spread out by a spreader and then scraped into 2-3 layers according to the intended size and thickness of the board.
– These layers are passed through heated pressor in which compressor presses them twice. In the first pressing (preliminary press), each layer is pressed separately. At the second time, all layers are squeezed together.
– Heat mode is set to remove water vapor and make adhesive solidify slowly.
– After pressing process, the boards are brought out so manufacturer can cut out the tangential section, sanded and classified.
b. Wet process
– Wood flour is sprayed with water to make a crust. They are spread out and put on a press wheel.
– Press once to the preliminary thickness.
– Finally, the board is passed through millwork at high temperature to compress the two sides and drain water out.
6. Advantages of MDF wood
– No warping, shrinking and hollowing like solid wood.
– In general, the price of MDF board is lower than that of plywood or solid wood.
– Because the MDF board is a very homogeneous structure, cutting edge is not chipped when cut.
– Flat and smooth surface of MDF can easily be painted or laminated to other decorative surfaces such as Melamine or Laminates.
– The output is quite stable and producing time is quite short, which is suitable for mass production, helps saving expenses and reducing production price.
– MDF surface may be much wider than solid wood so it is convenient for designing and producing large-size products without patching.
– Water resistant ability of MDF is quite low. However, this disadvantage can be improved by using moisture-resistant MDF (HMR MDF) instead.
– MDF has low hardness so it is quite easy to chip.
– MDF has a thickness limitation, so when you need to produce thicker products, you often have to pair the boards together.
– Patterns can’t be sculpted on the MDF surface like solid wood. It is possible to create colors and patterns by pressing decorative surface on MDF.
– Low quality MDF can affect the health of the manufacturer or user because of the Formaldehyde component.
8. Application of MDF boards
Decorative surfaces (Melamine, Laminates …) are often pressed on MDF for production and interior decoration such as tables, chairs, beds, cabinets, shelves, doors, and so on.
Video: manufacturing process of MDF