Fiber boards are sheet materials that are formed from wood fibers. They are made from wood waste or low-quality round wood. Sometimes wood waste and low-grade wood at the same time can be used as raw materials.
Fiberboards are soft and hard. Solid fiberboard is one of the most important and popular structural materials used in furniture manufacturing. As a rule, such plates are used for the manufacture of the back walls of cabinets, plugs and base boxes for upholstered furniture, the bottom of furniture drawers, etc. In addition, rigid packaging elements for disassembled furniture are made of fiberboard. Plates also found their application in construction (external and internal elements, agricultural buildings), in automobile and shipbuilding, production of containers and boxes, and in other industries.
Fiberboard compares favorably with natural wood and plywood in price, quality and design features. They are isotropic, not susceptible to cracking, have increased flexibility and at the same time are characterized by good elasticity. Soft wood-fiber boards are used in standard wooden house-building for insulation of panels, enclosing panels, attic floors, soundproofing of interior partitions and soundproofing of special rooms. Solid slabs are also used for interior wall cladding, flooring, panel door construction and door leaf filling.
Superhard slabs are used for the installation of clean floors in industrial buildings and office premises, for the manufacture of electrical panels, panels and other structures at specialized construction sites. Fiberboard has a long service life - more than twenty years. Conventional paint on the surface of the plates retains its properties for 15-18 years when used outdoors. At the same time, natural wood painted with the same paint quickly burns out.
Depending on the strength and type of the front surface, fiberboards are divided into several grades: T (solid boards with an unfinished front surface), T-C (hard boards with a front layer of fine wood pulp), T-P (hard boards with a tinted front layer ), T-SP (solid plates with a tinted top layer of fine wood pulp), ST (high-strength hard plates with an unfinished front surface), ST-S (high-strength hard plates with a fine wood front layer) hydrochloric mass). Solid plates of grades T, T-S, T-P, T-SP are also divided into two groups A and B, depending on the level of their physical and mechanical properties.
Due to its properties and widespread use, these products are always in high demand; therefore, their production is a profitable business. True, its organization (on a large scale) requires significant investments.
There are two of the most popular solid wood fiberboard manufacturing technologies: wet and dry. There are also intermediate methods (wet and semi-dry), but they are rarely used, so we will not consider them in detail in the framework of this article. In the wet method, a carpet of wood pulp is formed in an aqueous medium. Then, separate webs are cut from the carpet, which, when wet (humidity reaches 70%), undergo hot pressing.
In the dry method, the carpet is formed from air-dried wood pulp, and the plates are obtained by hot pressing the webs with a moisture content of 5-8%. In the semi-dry method, a carpet of dried wood pulp is finally dried in air, and the webs themselves with a moisture content of about 20% are processed by hot pressing. The wet method is based on the formation of a wood-fiber carpet in an aqueous medium, drying of the canvases, and subsequent hot pressing of dry canvases having a moisture content close to zero.
As raw material for the production of plates in any way, natural wood is used. First, it is crushed into wood chips, then converted into fibers, from which a carpet is subsequently formed. Sawmill and woodworking waste, wood longitude, logging waste, shallow roundwood from thinning are most often used for the production of fiberboards. As a rule, the raw material enters the site of the enterprise in the form of round wood, wood chips or battens, and in the production workshop it is supplied in the form of wood chips that meets certain requirements.
For the manufacture of conditioned wood chips, the wood is divided into sizes corresponding to the receiving chuck of the chopping machine, then it is chopped into chips, sorted to select the desired size with regrinding of a large fraction and removing fines, metal objects are removed from the chips, then it is washed to remove dirt and extraneous waste.
The most widespread among domestic producers of fiberboard was wet technology, although it is already considered obsolete. Its popularity is explained by relative simplicity, but it is more expensive and less environmentally friendly.
This technology resembles that of paper and paperboard. The slabs are cast from wet pulp, which is formed on a mesh metal tape and is fed into a hot press. Excess water is squeezed and evaporated, resulting in a densification of the plate structure. Various emulsions (paraffin, oil and resin), as well as precipitants (usually aluminum sulfate) can be added to this composition to impart qualities such as strength and water resistance to the final product. The reverse surface of the plate with this production method has a corrugated texture from contact with the grid.
Dry technology for the production of plates has certain differences, the main one of which is that the formation of a fibrous carpet occurs in the air, and not in an aqueous suspension. The main advantages of this method compared to the previous one: the lack of runoff and the low consumption of fresh water during production. The technological process for the production of fiberboard in a dry way includes several stages: acceptance, storage of raw materials and chemicals; cooking wood chips; steaming, grinding wood chips into fibers; preparation of a binder and hydrophobizing additives; mixing fiber with a binder and other additives; fiber drying; carpet molding; preliminary consolidation (prepress); pressing; stove conditioning; plate machining.
In the production of fiberboard in the dry method, experts recommend choosing hardwood as a raw material, which is due to the fact that they provide a more uniform carpet density than long coniferous fibers. However, to reduce the cost, you can mix different types of wood, but taking into account the peculiarities of its structure (mixed species must have the same or similar densities).
In the process of steaming and grinding wood, its partial hydrolysis occurs. For steaming, continuous devices of various systems are used, and for grinding - defibrators and refiners. With the dry production method, thermosetting resins are introduced into the wood fiber mass, since the ductility of the fibers at low humidity is not high enough, and the short pressing cycle under such conditions does not provide the strength of the joint between the components of the wood board. In addition, molten paraffin or other additives are introduced into wood chips or pulp to increase the water resistance of the finished product. Sometimes, in the manufacture of special-purpose boards, chemicals are also added to the mass. However, they are not washed into drains, as in the wet method, but remain on the fibers. Phenol-formaldehyde resins are generally used for bonding, with resins with a minimum free phenol content being preferred.
The milled fiber that has passed the defibrators is separated from the steam in dry cyclones, from where it is then fed via pneumatic conveying to the dryer or to the second grinding stage to closed grinding machines. In this case, the raw material loses up to 10-15% of its moisture. Fiber drying can be carried out in dryers of any type (tubular, drum, aerofont, etc.) in one or two stages (but experts advise to give preference to two-stage drying). In the dryer, the fiber is dried to an air-dry state, and its moisture is reduced to 8-10%. In the manufacture of dry fiber boards, the carpet is formed using air on a mesh conveyor belt. A vacuum is created above the tape to increase the fiber packing density. The mass is laid on the conveyor either by the method of vacuum molding or by the method of free fall of fiber on special machines.
The continuous carpet, which is obtained after passing the vacuum forming machine, is quite difficult to transport, since its height can be from 100 to 560 mm, and its strength is still not large enough. Therefore, before the blade gets under the hot press, it is pressed in continuous belt presses, and the edges along the movement of the blade are cut with circular saws.
Depending on the composition of the raw materials (types of wood) and the type of binder used, the temperature of pressing the web can range from 180 to 260 ° C. For example, for softwood, it does not exceed 220 ° C, and for hardwood from 230 ° C and higher. As the pressure increases during pressing, the density and, consequently, the strength of the plates increase, but their water absorption and swelling decrease. Post-press processing of the plates involves preliminary trimming of the edges of the products coming out of the hot press, moistening the plates, format cutting of the plates to the specified dimensions and their storage. Plates, which are then sent for decoration, must be sanded.
There are two main advantages of using the dry method of fiberboard production over the wet one: high water consumption in the latter case, as well as the same structure (smooth on one side and mesh on the other).
When using dry technology, special equipment and additional raw materials will be required. For example, water-soluble phenol-formaldehyde resin and paraffin are used as hydrophobic additives. The list of typical equipment used in fiberboard manufacturing plants includes: ruby drum machines, gyration-type flat sorting machines, a steam-grinding system, aeration and drum type dryers (for drying carried out in two stages), a two-mesh vacuum forming machine, a hydraulic press, loading and unloading device, hydraulic pump station, air conditioning chambers, mixer, tanks, sawing machines, conveyors, etc.
The organization of an enterprise for the production of fiberboards requires considerable investments, but competition in this segment is relatively small. In total, in Russia, Ukraine and Belarus there are a little more than thirty relatively large factories that are engaged in the production of solid fiberboards. They sell their products in the domestic market. Indirect competitors to manufacturers of hardboard are hardboard manufacturers using wet process technology. Around the world, about 7 million cubic meters of insulating fiberboard are produced per year, with Germany alone accounting for 2.7 million cubic meters.
The payback period of the project (the construction of a large plant for the production of hardboard) is five years, taking into account financing. It is worth considering that the construction period of such an enterprise reaches 1.5-2 years from the month of receiving the investment and only six months will be spent on the development of project documentation. But you can reduce these terms to a year, including three months for the development of project documentation, if you buy an existing woodworking enterprise and technically convert it.
The internal rate of return on a project excluding investments is 27%. And the profitability of production is estimated at 116%.
According to estimates, the average annual net profit may amount to 270-280 million rubles. The total investment in this case reaches 1, 200 million rubles. To work at a large plant with a planned sales volume of 130 thousand cubic meters of fiberboard per year, a staff of 180-200 workers will be required.
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