Chipboard production equipment. How chipboard is made: equipment and manufacturing technology

Among the practical and multifunctional wood-based materials, chipboards or, simply, chipboard occupy a special place. Their production can take place both in large wood processing plants and at home.

The purpose

Chipboard is an environmentally friendly, easy-to-process, functional material, besides a high-tech alternative solution to solid wood. It is used in order to sheathe walls, roofs, make wall panels, create flooring for carpet or linoleum, floors, various partitions, manufacture a wide variety of furniture, packaging, construction of enclosing arrays, interior decor. What is the chipboard production technology? How is it made at home? We will consider these issues later in the article.

What is chipboard made of?

The basis of chipboard production is a process in which sawdust is mixed with a special adhesive mass and the resulting mixture is pressed under high pressure and high temperature. A big advantage of chipboard manufacturing is the use of sawmill waste.

Pressed boards have good strength, created by mixing sawdust mixture with glue (resin) hardened to a stone state. For the production of environmentally friendly types of material, an adhesive mass of minimal toxicity is used.

Chipboard production can occur on a small scale. In general, only the size of the slabs produced is limited, which should be no more than 50 x 50 centimeters.

The production of particleboard at home is the same process as in the industrial scale, but in miniature. All stages where automation has to be involved are replaced by manual work.

How chipboard is made at home

Consider the manufacturing sequence for chipboard:

• first, the sawdust mass is mixed in a medium-sized container (from 10 to 15 liters);
• then an adhesive solution is added, you need to make sure that the sawdust is completely saturated;
• given a tiled shape at high pressure;
• then, with the help of a high temperature, the billets are pressed, for this process special equipment is needed;
• the produced slab is air cooled and the edges are trimmed.

Surface lamination is carried out in the same baking press that is used in the production of uncut blanks. You can purchase a ready-made special laminate for chipboard, which can be "baked" to the surface in a certain way using an iron. Such coatings have a beneficial effect on the appearance of wood-based panels, but are not considered a full-fledged layer of laminate.

Equipment

Before making a chipboard, you need to prepare the equipment. The technology for creating this material is based on the use of elementary and practical equipment, which is connected into a common system. It is not necessary to use the most technologically advanced devices for making wood-based panels, but it is rather difficult to set up and maintain the working line.

Equipment list

The complete list of equipment for the production of chipboard includes:

1. Mixers, which are needed in order to obtain a homogeneous mixture prepared from sawdust and an adhesive (usually resin with special admixtures to create a solid structure).
2. Molding devices are needed to give viscosity and shape to the mixture.
3. High temperature pressing equipment and machine tools.
4. Coolers are used to cool hot chipboards faster.
5. Edge cutters that remove the edge from the slabs.
6. Grinding machines make the formed surface smooth.

The performance of all equipment in large-scale production is ensured automatically. The quality of work is monitored while maintaining the mechanism settings at the desired level.

All of the wood-based panel making equipment listed above will be suitable for work assuming ready-made raw materials are available.

If, in the manufacture of chipboard, the plans include the use of their own source material, then the equipment set must be supplemented with auxiliary equipment, such as cutting machines, chippers, mills and planing machines.

Among other things, additional equipment that will improve the manufacturability of wood-based panels includes conveyors, tables equipped with lifting mechanisms, ventilation systems necessary to remove sanding dust, drying chambers and conveyors. Consider how chipboard is made.

Manufacturing technology

Wood-based panels contain wood chips, which are generated as waste from wood production. In a typical work cycle, the non-functional mass turns into ready-to-use slabs.

Consider how do-it-yourself chipboard is made.

Manufacturing sequence

The manufacturing steps are as follows:

• first you need to find raw materials, sawdust and chips in the warehouse;
• then the raw material is prepared for work by grinding;
• materials are dried to obtain a suitable consistency for bonding;
• chips are sifted using automated sieves, sorted according to size;
• larger and smaller chips are mixed with each other;
• a resin adhesive is added;
• the mixture of viscous consistency is sent to the molding machine, which forms the wood-based panels;
• Chipboard is pressed under high pressure and high temperature;
• the plates are cooled;
• the edge is cut, and the resulting blanks are sawn into pieces of the required size.

So, we looked at how chipboard is made. This material must be sanded as a final step in the manufacturing process. It is the level and quality of grinding that directly depends on which grade the finished product will be assigned to. Particleboard of the first grade should not have scratches, stains, insufficient sanding, waves on the surface.

The necessary parameters of the wood-based panels are controlled both during production and after the chipboard is ready. The produced sheets are stored in blocks, which are stacked on special wooden pallets - pallets.

Milling process

Creation of curved surfaces from the inside and processing of corners on the outside is carried out during the milling process. A milling cutter is a cutter equipped with teeth, it usually has any regular shape (for example, a cone or a trapezoid). Chipboards need to be processed around the full thickness, which is different from harder materials. This is necessary so that random chips do not appear.

Before you start milling, you need to prepare. To do this, you need to cut out the contours of the planned figures in advance using a jigsaw or saw. They are usually processed manually or using a stationary mill. In this way, holes in the form of a cylinder and an oval of any size are obtained, which provides an aesthetic appearance of the finished board.

What is the process of laminating chipboard

Considering how chipboard is made, let us dwell in more detail on the lamination process. Any furniture, including cabinets, kitchen sets of any class, is made of wood-based panels, the surface of which has undergone a special stage in processing, has been laminated with special materials necessary to protect the product, as well as create a more aesthetic appearance. These products are called laminated chipboard or expanded laminated chipboard.

To laminate a product, it is necessary to apply a stable coating to its surface, with the help of which the appearance is improved, no additional processing is required.

The main steps in the wood board lamination process are as follows:

1. First, the highest quality material of the most durable and dense products is selected, which has little moisture.
2. The chipboard is coated with a primer to ensure the best adhesion of the laminate;
3. Now several layers of paper (no more than three) are applied, which are impregnated with the resin mixture. With the help of paper, the product will be more durable, and the coloring of the outer part creates an aesthetically pleasing appearance of the board. The layering process is accompanied by pressing at a high temperature.
4. Further, the product is quickly cooled, sometimes by sprinkling with water.

The surface of the chipboard must be carefully polished before being laminated. If even small roughness and uneven spots remain, this can lead to deterioration of the laminate layer and, accordingly, the product will be rejected. The process of lamination with your own hands at home is very difficult to produce with high quality, therefore, often for subsequent use, already processed, industrially made laminated chipboards are purchased.

Almost any business in the construction industry is profitable and, with a competent approach to business, regardless of seasonality, quickly pays off. And especially promising here is not even the provision of services to the population, but the direction of the production of high-tech materials that are in demand among consumers. Such business ideas include the manufacture of chipboard (chipboard). The production of laminated chipboard will be in demand among buyers, if you think over the process to the smallest detail and conclude lucrative contracts with customers. Chipboard is a practical, relatively inexpensive, environmentally friendly material that has been a leader in the construction niche for many years. It is actively used for furniture items, for roofing and floors, for the construction of interior and room partitions.

Our business valuation:

Initial investments - from 8,000,000 rubles.

Market saturation is medium.

Difficulty starting a business - 7/10.

The production and sale of chipboard boards, despite all the simplicity of technology and the availability of equipment, will be associated with many problems, the main of which is high competition. Surely, in every region there is a woodworking enterprise engaged in the production of chipboards. And therefore, in order not to waste money on the launch of production, it will not hurt to analyze a specific sales market beforehand. There are a lot of potential customers, and a small enterprise will have enough and a couple of wholesale customers to stay afloat.

So, how to open a particleboard production in Russia, which is competitive and profitable?

What assortment to offer to consumers?

Chipboard production as a business will only be profitable when any client who contacts the company will find what he was looking for. Taking this into account, it is important to organize the production of products of various types, properties and price categories.

Experts identify many classifications of chipboard. The main one is the gradation by the number of layers:

• single layer,
• three-layer,
• multilayer.

According to the appearance and quality of the raw materials used, chipboards are divided into grades:

• Grade 1. Material with smooth edges and smooth surface.
• Grade 2. Material with slight violations of the integrity of the structure - scratches, chips.
• Grade 3. The material can be classified as defective products.

In order to offer customers a material suitable for different types of work, it is important to think over the recipes for boards that differ in density:

• low density - up to 550 kg / m 3,
• medium density - 550-750 kg / m 3,
• high density - over 750 kg / m 3.

It is great if the process of making chipboard will provide for finishing the material with polymer films, veneer, plastic or paper.

It is important to think over the assortment at the initial stages of starting a business, since many subsequent steps will depend on this - the purchase of raw materials, the purchase of equipment.

Description of the chipboard manufacturing process

Chipboard production flow chart

Even if a small do-it-yourself chipboard production is planned, it is important to study the material production technology in detail. The quality of the finished product will also depend on the quality of the technological stages.

The main advantage of this area is the simplicity of the technology. All stages of the production chain are interconnected, and it will not be difficult to understand them even for a person far from the industrial sphere.

The main raw materials that will be supplied to the workshop are sawdust, small wood waste. The components used are readily available and inexpensive. And to make chipboard production less costly, it would be nice to establish direct supplies of raw materials from local woodworking enterprises. It is quite natural that the closer the supplier is, the cheaper the raw material will be.

It is a common practice when furniture factories hand over industrial waste at a lower cost (or even completely free), and in return receive high-quality chipboard from an entrepreneur at an attractive price for themselves. This is the kind of barter it turns out.

Chipboard production technology is hot pressing. The scheme is as follows:

• Raw materials are dosed and mixed with a binder - thermoactive resin.
• The mixture is poured into special molds.
• Mixed molds are exposed to high pressure and elevated temperature.
• The resulting slabs are removed from the molds, if necessary, they are additionally processed - cut, polished, pasted over with decorative materials.

Despite the fact that the production of furniture chipboard is very simple, when organizing a full-fledged workshop, a qualified technologist should be hired, who will strictly control the quality of the input raw materials and all technological modes. Control over the production process is indispensable, since here, as in many other areas, the rule is that the higher the quality of the product, the more profit it will bring.

Technical equipment of the workshop

Chipboard production line

After the assortment has been thought out and the technology has been studied, you can proceed to the next stage of organizing your business - to buy equipment for the production of chipboard. And this stage is one of the most important, since it is the most costly.

It will be difficult to organize a home business for the production of chipboard, because the financial investments here are quite large - not every novice entrepreneur will be able to start a workshop without attracting outside investments.

The "middle" line for the production of chipboard includes the following machines and devices:

• Mixers with dispensers.
• Forming machines.
• Heat presses.
• Coolers.
• Cutting machine for finished slabs.
• Grinding machine.

The indicated equipment implies the use of ready-made components for chipboard production - sawdust and shavings. But if it is planned to organize a full-cycle plant (that is, with crushing of boards and logs), then additional component lines will have to be provided - crushers and a sieve.

The price of equipment for the production of chipboard is quite high, and the final cost of the devices will depend on their capacity, degree of automation and equipment. For example, a fully automated line, where all production stages are carried out without human intervention, and with a capacity of up to 150 sheets per shift will cost at least 17,000,000 rubles. But even lines of lower productivity (up to 50 sheets per day) will not be affordable for many entrepreneurs - at least 8,000,000 rubles.

Considering the considerable cost of the equipment, it makes sense to think about some savings options:

• Supported equipment costs 2 or even 3 times cheaper than new equipment.
• If you lease a line, you can avoid huge initial investments.
• Chinese machine tools can cost significantly less than equipment of European brands.

The profitability of the chipboard business

Many entrepreneurs have already proved in practice that a mini particleboard plant with established distribution channels brings its owner consistently high incomes.

The sooner it turns out to establish sales to wholesale customers, the sooner all costs will be recouped. At first, it will be difficult for a young enterprise to enlist the support of large wholesalers. But even here it is quite possible to achieve success, for example, by slightly lowering prices for supplied products.

Before starting to calculate the profitability of an enterprise in a business plan, it is necessary to present those items of capital expenditures that will have to be incurred to open a business. According to minimal estimates, the launch of a small workshop will require a cost of ≈8,000,000 rubles.

This includes the following items of expenditure:

• Purchase and on-site installation of equipment.
• Purchase of raw materials.
• Preparation and rental of premises.
• Registration of the company.

And these costs will increase significantly if you buy a machine for the production of chipboard of greater power. But for a start, a line of low productivity is enough.

Speaking about the profitability of the mini-plant, it is hardly possible to indicate exact numbers, because everything here is strictly individual, if we take into account the prices for finished products in each region and the volume of sales. On average, chipboard is sold at a price of 6,500-10,000 rubles / m 3. The cost of the material varies between 4000-6000 rubles.

If there are no problems with sales, the enterprise can go to zero after 2 years. And these are excellent indicators of profitability.

Furniture manufacturing is a highly lucrative business, second only to the construction industry. However, this segment is very busy at the moment, so a newcomer will need a lot of effort to effectively enter the market.

If the question arises of how to start a business, it is worth saying that many entrepreneurs refuse to believe that it is much more profitable to produce raw materials for the furniture industry than finished products. At the moment, laminated chipboard (chipboard) is a very popular material that is actively used not only for the manufacture of furniture, but also for various interior finishing works.

Of course, chipboard is inferior to wood in a number of parameters, but ease of processing and low cost are its main advantages, therefore, this material is in great demand every year.

If you decide to organize the production of laminated chipboard, then you should know about one more advantage of such a solution: at the moment you will have a small number of competitors on the market. The result of this can be called the drawing of a large sales market, since almost all furniture factories are ready to purchase materials for the production of their products.

Chipboard production - competent business organization

Even a child realizes that specialized equipment is required to make something. In this case, it is also needed. Chipboard production cannot be organized without the following tools:

• Special drying machine. With its help, laminated paper is made.
• Press. With its help, chipboard with such paper is pressed in.
• Calibrating grinder (it affects the quality of the resulting surface).

So, you need not only the main equipment for laminating chipboard, but also the accompanying one. First of all, we can talk about a device designed for the preparation of an adhesive base, which is then poured into molds and pressed into plates.

Chipboard base

Chipboard, or chipboard, is a fairly popular building material, as well as the basis of chipboard used for the production of furniture. Particleboard is actively used in the following areas:

• in the construction of floor coverings;
• in the process of designing a variety of wall panels;
• for the production of furniture, as already indicated;
• as a roof sheathing material.

Such a production may well be called processing, since waste from wood enterprises serves as the main raw material for the manufacture of such boards.

Production methods

Chipboards can be manufactured in one of two ways - batch and continuous. The batch method assumes the use of intermittent pressure storey processes, and the continuous one - constructional processes.

Features of the manufacture of chipboard

The production process in this case can be divided into a number of main stages:

• Preparatory. At this stage, the preparation of raw materials is carried out by crushing wood to obtain chips of the required size. If you purchase ready-made raw materials immediately, then this step can be skipped.

• The second stage involves mixing the chips with a binder, which is traditionally used as glue. It is very important to adhere to strict proportions, since with an excess of glue, you can get a product that has deteriorated technical properties, and therefore such plates will be considered defective.

• Next, the prepared mixture is placed in special molds, which are then pressed in. The influence of factors such as pressure and a sufficiently high temperature allow the material to set to form a coherent whole.

• Next, the resulting blanks are placed in a special chamber for drying.

• After that comes the stage of trimming the edges of the slabs.

• The final step is sanding the slab.

You can organize production in a warehouse, where you can install not only a line for the production of chipboard, and subsequently laminated chipboard, but also stands where the finished product will be stored.

Necessary equipment

If we consider the option of production, when all operations are carried out at your enterprise, starting with the procurement of the raw materials themselves, then a whole range of instruments and machines will be required.

The preparation of raw materials implies the presence of such devices:

1. equipment for processing logs into chips;
2. drying chambers for chips;
3. planing machine;
4. vibrating sieve.

The material production process involves the involvement of such equipment:

1. an apparatus for mixing shavings and a binder;
2. forms where slabs will be harvested;
3. thermopress;
4. drying or cooler for products ready for further processing.

To implement the final stage, you will need:

• sawing machine, with which you will give the sheet some specific dimensions;
• a machine that grinds the ends;
• devices by means of which coarse and fine grinding is performed.

The production of laminated chipboard will require the involvement of a press in the process, which applies double-sided lamination. You may need transportation devices such as belt or roller ones.

About lamination

Initially, the production and lamination of chipboard panels was a very laborious process that required colossal energy consumption. Almost 30 years ago, completely new types of resins were mastered, with the help of which it was possible to start using new processes for laminating boards.

During production, it is very important to distribute the load as evenly as possible, which can significantly improve the quality of the board. A product made in this way can withstand a large number of deformations and loads, which is very important.

The options for how to properly laminate paper have been developed for years, but now a solution has been found, and it is very effective. The paper is made in impregnating machines, where it is processed with resin, which makes it possible to obtain a decorative film from it, which becomes plastic-like under the press.

For the production of chipboard, wood raw materials, a binder and a hardener for it are used.

Wood raw material

Specially prepared shavings, wood shavings-waste and sawdust can be used as raw materials for the manufacture of chipboard.

Specially made shavings (so-called technological chips) are obtained from firewood, small-sized forest raw materials and some wood waste. For its manufacture, chip machines are used, which chop wood with special knives. After planing, the technological chips are dried and separated into fractions. Such shavings make the most durable board with a relatively smooth surface.

Waste shavings are obtained at sawmills, plywood and other woodworking industries. A board made of such chips is inferior to a board made of technological chips both in terms of mechanical strength and surface quality.

The sawdust board has a flat, smooth surface, but low mechanical strength. Therefore, sawdust is not used in its pure form: usually only the outer layers of multilayer slabs are made of them.

Binder

The binder is about 8 ... 13% of the volume of the board, but the cost of the binder is up to 30% of the cost of chipboard: therefore, its price is very important.

The increased content of resins leads to an increase in formaldehyde emission, which is standardized by GOST, and a very high content also reduces the quality of products. Reducing the amount of binder increases the yield of rejected products and increases the pressing cycle time, which is also undesirable. Therefore, technologists are trying to select the optimal amount of binder for each batch of wood raw materials.

As a binder can be used:

1. Urea-formaldehyde resins. They dissolve in water and therefore do not protect the chipboard from moisture. The board glued with urea-formaldehyde resins can withstand a single short-term wetting in cold water, but with prolonged or repeated exposure, or upon contact with hot water, it quickly swells, loses strength and collapses. The advantages of urea-formaldehyde resins are their relatively low price and the absence of phenol. This allows you to use chipboard without restrictions in residential premises. They are the ones that are used most often.

2. Phenol-formaldehyde resins do not dissolve in water and quite effectively protect chipboard from premature swelling when wet. The downside is the high price and non-zero emission of toxic phenol. It is because of the emission of phenol that phenol-formaldehyde resins are used extremely rarely for the production of particle boards.

3. Melamine-formaldehyde and urea-melamine-formaldehyde resins contain melamine, a substance that replaces phenol. Such resins, like phenol-formaldehyde resins, do not dissolve with water, but at the same time they do not contain phenol, which allows them to be used in residential premises. The only drawback of such resins is their high price. It is because of the price that melamine-formaldehyde resins are not widely used and are rarely used in the production of MDF, chipboard and plywood.

The binder does not only consist of resins: some water is also added to it. The water content depends on moisture content and chip fraction. In different layers of multilayer boards, the water content in the binder can be different.

Hardener

The hardener shortens the pressing cycle and increases the mechanical strength of the chipboard. It can be added to the chips with or separately from the binder. When added together with the resins, the hardener is distributed more evenly, and this improves the quality of the boards, but if the line is working with downtime, the hardener dries up and clogs the nozzles. Therefore, it is often added to forms separately from the binder.

Production stages

Drying of wood raw materials

For the production of chipboard, chips with a moisture content of 2 ... 4% are used. Wood from the warehouse has a much higher moisture content: therefore, the shavings are additionally dried in special convection dryers at a temperature of about 500 ° C.

Resinification

For high-quality pressing, the chips must be evenly covered with a thin layer of binder. Processing with a binder is called resinification. It is carried out in special mixers that spray the binder using nozzles. Modern equipment allows you to cover literally every wood particle with a thin layer of resin, and from all sides.

Resinated wood comes out of the mixer and is fed to the press.

Pressing

Pressing is carried out in special presses, which may have different designs. In any case, the chips mixed with binding agents are pressed at a temperature of 220 ... 230 ° C, then cooled and subjected to additional processing.

There are two types of pressing: flat and extrusion. In flat pressing, the press presses on the future plate perpendicular to its plane - usually from top to bottom. This method makes it possible to obtain multilayer boards, and the strength of the chipboard, all other things being equal, will be higher than that of the chipboard by extrusion pressing. Therefore, at the moment "flat" technology dominates the market.

During extrusion pressing, a mixture of chips with a binder is squeezed into the space between the heated plates from the side, and the pressure vector is directed parallel to the plane of the plate. The strength of the slab is lower, but this method makes it possible to obtain ultra-light hollow-core slabs. Extrusion presses are rarely used today.

Pressing cycle

The duration of the pressing cycle in the production of chipboard is from 30 to 60 seconds and depends on the temperature of the press and the density of the board. The higher the density of the chipboard, the longer it needs to be pressed; the higher the temperature, the shorter the cycle. At the same time, the moisture content and size of the chips, the type and amount of binder, the quality requirements and the characteristics of the press itself also affect the optimal temperature and duration of pressing. As a rule, technologists empirically select the cycle parameters for each batch of raw materials.

Trimming and cooling chipboard

After pressing, the finished and still hot chipboard is cooled and trimmed to the required format. Pruning can be hot or cold. During hot trimming, the slab is still hot into the sizing machine. This technology increases productivity, but during trimming, a heated and still soft chipboard can deform. With cold pruning, the risk of warping is minimal. The disadvantage of such trimming is the need to add a fan cooler to the production line, which is rather slow.

Conditioning

After cutting and cooling, the chipboard is kept in an intermediate warehouse for 120 ... 140 hours. At this time, the binder continues to cure inside the board, it gains hardness and strength. Upon completion of conditioning, the board is subjected to additional processing.

Finishing chipboard

Finishing is the final stage of chipboard production. Most often used:

• grinding from one or two sides;
• lamination with paper-resin films;
• veneering.

Package

Finished chipboard is marked and packaged in bundles. In this form, it is sent to the warehouse or directly to the buyer.

Chipboards have become, obviously, one of the most famous and widespread wood-based materials in the last 10-15 years. They are the main structural material in furniture production, and recently they are gaining more and more recognition in construction, in particular in the production of low-rise buildings.

Raw materials for chipboard - various types of sawmill waste, logging, woodworking (slabs, slats, pick-off, twigs, cuttings, shavings, sawdust), as well as low-quality round timber. The importance of this production becomes clear: from waste and low-quality wood, a material is obtained from which high-quality, durable products are made.

All lumpy waste is crushed into chips on chippers. From wood chips, as well as from shavings, waste and sawdust, shavings are prepared on special rotary machines. Chips are made from round timber either directly from a log on machines with a knife shaft, or according to the chip-chip scheme, when chips are first made, and then chips are made from chips. Before feeding the logs to the chipped machine, they are cut into measured pieces (usually 1 m long).

The shavings should have certain, predetermined dimensions (thickness 0.2-0.5 mm, width 1-10 mm, length 5-40 mm). The smallest chips are directed to the outer layers of the board. In addition to observing the dimensions, it is also necessary to ensure that the chips are flat, of uniform thickness, with an even surface. The shavings for the outer layers after the shaving machines undergo additional grinding on crushers (here the width decreases) or in mills where the thickness changes. The latter operation is of particular importance for boards that are finished with the lamination method, since in this case high demands are placed on the quality of their surface.

The produced raw shavings are stored in bunkers, where they are fed by a pneumatic conveying system or mechanical conveyors. Raw shavings are fed from hoppers to dryers. It is necessary to dry the shavings to a moisture content of 4-6%, and for the inner layer - up to 2-4%. Therefore, the chips of different layers are dried in separate dryers. In the production of particle boards, as a rule, convective dryers are used, in most cases of a drum type. In the furnace of the dryer, gas or fuel oil is burned, the temperature in it is 900-1000 ° C. At the inlet to the drum, the temperature of the drying agent reaches 450-550 ° C, at the outlet it is from 90 to 120 ° C. The drum has a diameter of 2.2 m and a length 10 m, it is installed with a slope of 2-3 ° towards the entrance of raw chips.

After drying, the chips are sorted either on mechanical (sieve) units, or pneumatically. On these machines, the chips are divided into fractions for the outer and inner layers. This concludes the production of shavings. The author should note that this part of the technological process largely predetermines the successful implementation of subsequent operations, the productivity of the process, and especially the quality of the boards. Therefore, much attention is paid to the preparation of shavings (the operation of equipment in this area, the qualifications of operators).

The shavings are mixed with a binder in special units called mixers. This operation is difficult, since the production technology requires covering each chip with a binder. Non-resinous shavings do not stick together, and excessive resin on the shavings leads to overconsumption of the binder and poor quality of the boards. The binder is supplied to the mixer in the form of solutions. Their concentration in the flow of the outer layer is 53-55%, the inner layer is slightly higher (60-61%). Currently, the most common mixers in which a sprayed binder (particle size 30-100 microns) is directed by a torch onto a stream of shavings suspended in air. These two streams are mixed, the binder is deposited on the surface of the shavings. Mixers generally need fine adjustments to maintain strict proportions between chips, resin and hardener. After resinification, the chips are directed to the forming machines by belt or scraper conveyors.

Forming machines take the tarred shavings and pour them into an even layer (carpet) onto pallets or conveyor belts passing under them. Particle carpet is a continuous strip of a specific width and thickness. It is divided into packages, from which they are subsequently formed during hot pressing of the board. Naturally, the uniformity of the carpet filling directly affects the quality of the slabs (equal density, equal thickness). In addition, shaping machines must fill the outer layers with small chips.

The conveyor transports the packages, which after passing the press for pre-pressing become dense briquettes with transport strength. Two fundamentally different types of main conveyors are currently known in the particle board industry. They differ in that in one case the packages (and then briquettes) are moved on metal pallets, in the other type of the main conveyor - on belt conveyors when the pressing is palletless. Each main conveyor design has advantages and disadvantages. The pallet method is simpler and more reliable, but the plates are obtained with a greater difference in thickness, the thermal energy consumption is greater. The palletless method provides some energy savings, improved board quality. The designs of the main conveyors are described in sufficient detail in the special literature, and if necessary, the reader can, with its help, study in more detail this main technological line of particle board factories.

The author has already mentioned that the main conveyor includes a press for pre-pressing. Pressing is necessary to reduce the thickness of the package and increase its transportability. The thickness of the bag is reduced by 2.5-4 times (more with palletless pressing). The pressure in this case is 1-1.5 MPa for pressing on pallets and 3-4 MPa for palletless pressing. Pressing is usually carried out in single-deck presses, sometimes it is a mobile press, more often a stationary one.

After pre-pressing, the briquettes on pallets are fed to a multi-storey hydraulic press for hot pressing. With palletless pressing, the briquettes are laid out with a belt directly on the hot press plates; During pressing, heat and pressure are applied to the briquette. The reader will obviously understand that the duration of the hot pressing determines the cycle time of the press and thus the productivity of the entire plant. Therefore, great attention is paid to reducing the pressing cycle. The cost of a press for hot pressing, as in the production of fiberboard, is 20-25% of the cost of all plant equipment, and therefore the problem of its best use is a constant concern of the workers of factories, and the profession of a press operator is the most revered.

Pressing is carried out at 180 ° C and a specific pressure of 2.5-3.5 MPa. The duration of pressing is 0.3-0.35 min per 1 mm of plate thickness. Modern presses have hot plate sizes of up to 6x3 m and up to 22 working spaces (22 chipboards are pressed at the same time). The height of the press reaches 8 m.

Reducing the pressing cycle (increasing the productivity of the press) is achieved by increasing the pressing temperature, using resins with a shorter curing time, and increasing the number of working intervals. These measures were implemented at most of the factories, which made it possible to increase the productivity of the presses from 35 to 80-85 thousand m3 of plates per year.

The author considers it necessary to inform the reader that there are also one-story presses. Their length of hot plates reaches 20 m, and the total length of the main conveyor is 60-70 m. When servicing it, the operator has to use a bicycle to move it.

The finished press plates are unloaded onto the receiving (unloading) stacker, and from it onto the line, where they are cut from four sides (format cutting line). This line often includes a plate cooling unit. Then they fit into the feet, where they are kept for at least 5 days. Next, the slabs are ground using the equipment and tools that were described above. In accordance with the requirements of the standard, the boards are sorted and then either cut into blanks for furniture boards, or sent to consumers in full format.

In conclusion, we point out that 1.75-1.85 m 3 of wood, 70-80 kg of resin (in terms of dry matter), 1.4-1.5 tons of steam, 160-170 kW are consumed per 1 m 3 of chipboard -h of electricity. Labor costs are 2.5-4 man-hours per 1 m 3.

It should be noted that the production of particle boards is constantly being improved: new types of boards appear, fundamentally new machines, more efficient binders. Of particular interest are chipboards, the dimensions of which are tens of millimeters in length and width; the chips are located in the plane of the plate. This ensures high static bending strength of the slabs,
which is important when using them in construction. Such boards (made of oriented large-format chips) are successfully replacing plywood, which is becoming increasingly scarce.

In recent years, non-toxic, fast-hardening resins have begun to be used, which increases the productivity of presses, and therefore of factories, eliminates gas pollution in workshops, and allows the use of plates inside residential premises. The volume of particle board production is constantly growing, this trend will continue in the future. An industry equipped with modern equipment requires highly qualified workers, engineers and technicians who are well versed in the technology of mechanical and chemical processing of wood, electronics, hydraulics, and heat engineering.