The drying process is the initial point in the entire preparation of the semi-finished product (wood) before processing.
A drying chamber for lumber and wood is an excellent solution to the problem; you can make it yourself. In order to avoid deformation of the logs, drying is carried out in specialized conditions, which are carried out exclusively in a drying apparatus.
Why is drying needed?
For a long time, when making any wood crafts, they used timber that had been cut down several years earlier. Products made from damp or under-dried boards will warp or develop numerous cracks.
When the tree dries out, it shrinks, the raw wood material will “sink” over time, and huge wide cracks will form in the log house. Under-dried semi-finished products are likely to develop fungus. But it is not advisable to overdry the tree, because it will begin to absorb water, which will lead to swelling.
What are the modes of drying chambers?
There is a whole list of drying modes for wood materials. In built with my own hands In machines, the mode from lowest to highest changes gradually, removing all excess water from the semi-finished product. The drying process is carried out based on the following material characteristics:
- wood species;
- overall dimensions of the semi-finished product;
- final and initial humidity levels;
- specifics of the unit;
- quality indicators of lumber.
The drying process can be characterized by high temperature or low temperature. The second case is notable in that primary drying is performed at a mode that does not reach 100ºC.
Low temperature conditions may be as follows:
- soft - after drying is completed, semi-finished products have their original properties without changing strength or color;
- moderate - the color changes slightly, the strength characteristics are slightly reduced;
- accelerated - during subsequent processing (breaking, sawing, cutting), increased fragility is possible, the color fades.
Changing the temperature regime during low-temperature processing is carried out in three stages.
High temperature processing is carried out in two stages. The second stage begins when the moisture level of the semi-finished product decreases to 15%. Such technological process used when further construction of secondary structures is necessary.
Main types of drying chambers
Drying of semi-finished wood products in industrial volumes is carried out in specialized drying apparatuses. Moisture is removed from the wood by heated air, which subsequently escapes into the atmosphere. The device ensures a full drying cycle for lumber. The machine body can be:
- solid/prefabricated metal;
- made using building materials.
The latter are mounted directly in carpentry workshops in the form of a structure, or as free-standing ones. The walls are made using reinforcement and concrete mortar. As an alternative, you can use brick. Large factories make a system of cameras, combining them into entire modules with centralized control and communications. Air moves inside the dryer in a horizontal plane or vertically transversely.
Heat sources in the dryer:
- radiant source from specialized units;
- hot shelves;
- electric current that passes through raw semi-finished products;
- high frequency electromagnetic field.
The chambers are equipped with main and auxiliary equipment. Basic systems:
- supply and exhaust equipment;
- heat sources;
- humidifiers.
Based on the principle of operation, drying machines are divided into:
- convective equipment;
- condensation equipment.
In convection machines, semi-finished products are “battered” with hot air waves, the heat is directed by the convection method. The time for completing a full cycle varies from 5 to 13 hours. Similar units are installed in large-scale sawmills.
Chamber-type dryers are more compact; a constant temperature and environment as a whole are maintained throughout the entire volume. This type of dryer will allow you to dry any type of wood material to the required condition, which is why many entrepreneurs who need to dry lumber choose chamber dryers.
Based on the technology of the drying process, the moisture that is released from the wood settles on the cooling elements, is directed into containers and then drained. The efficiency of such a unit is quite impressive, but it is time-consuming and leads to large heat losses. Price policy machines and the profitability of condensation drying is lower than convective drying.
Drawing
Drying chamber for lumber: step-by-step instructions
To build a drying apparatus with your own hands, you do not need to use technical documentation. You just need to provide:
- the area where the camera will be installed;
- insulation materials;
- source and communications for creation high temperature;
- blowing
The area of a car built personally is usually no more than 10 square meters. Room square section more suitable for ensuring the movement of warm air currents. It is preferable that at least one of the walls of the equipment be concrete, the others can be made of wood. The inside of the chamber must be insulated. Great insulation material- wood shavings. If you don’t have foil on hand, you can replace it with penofol.
A separate extension for the dryer can be constructed from aluminum sheets; this design will serve for a very long time. The base is made on the basis of profiles, it is covered with sheets of metal, which is then insulated. The thickness of the insulation must be at least 150 mm. The floor is covered with roofing felt material, a thick layer of shavings is poured on top, which will be excellent for heat conservation.
The heat source can be supplied as a heating pipe system. The liquid temperature in the pipes should be 60...90ºС. For an oversized chamber, having a two-burner stove would be quite acceptable. If the source is located directly in the room, it must be lined with bricks. Brick is capable of perfectly collecting heat and directing it to a machine for drying lumber.
Continuous circulation of liquid is important, which is provided by a compressor or an entire station. The room must be equipped with wet and dry thermometers.
For more convenient loading of semi-finished products into the chamber cavity, you can use a rail cart.
Video: DIY lumber drying chamber.
As you know, freshly cut wood is not used in production and construction due to the presence of a large amount of moisture in it. Such lumber is called wet. To improve its mechanical and physical characteristics, a lumber drying chamber is used. As a result, biological stability increases, the level of strength and other qualities of wood rise.
The need for drying lumber
Previously, when making various fakes using wood, they used timber that had been cut down years earlier so that they could dry evenly.
It is very important to get rid of moisture from the wood. For example, in the manufacture wooden furniture made from lumber that is too wet will cause it to dry out over time. After all, the tree can dry out, its size decreases and leads to damage.
Making a door from very dry material can cause it to swell, causing it to not close. If door panel If it is selected from blanks that have been dried intermittently in volume, a rupture may occur or it will warp. Its deformation is noticeable in different planes and at different speeds. As a result, tension lines appear inside the material, which cause cracks.
In addition to the fact that the board cracks, transverse deformation is also possible; it can bend in an arc and raise the edges unevenly.
Mostly, cracks in the board are observed along the fibers, initially from the end.
Therefore, all logging operations are advised to dry out. Moreover, drying wood protects the material from damage by fungus, which destroys the tree, prevents changes in the shape and size of the tree, and increases the physical and mechanical qualities of the wood.
Drying takes a long time, this procedure is complex and expensive. According to established technologies the material is heated with superheated steam or a hot air stream.
Dried, it lasts longer. And also during use, lumber does not deform. Drying takes place in steam chambers, where damage to the material inside is prevented.
The concept of moisture content of lumber
Absolute humidity is the percentage of the weight of liquid present to the weight of a specific volume of dried material. The presence of relative humidity is characterized by the percentage of the weight of the liquid removed (by 2 weighings) to the original weight of the material.
The usability level is calculated taking into account the relative humidity. The value indicates the readiness of the lumber for gluing and drying. If the humidity value is more than 30%, the tree is considered damp, and there is a risk of fungal infection.
Moisture content in wood is divided into two groups. 
Free moisture– present in cell cavities and intercellular spaces. The presence of such moisture is determined by the conditions in which the tree grew and how the sawn pieces were stored. When drying, free moisture leaves the board very quickly.
Related (structural)- a liquid that is found in the walls of cells. Each type of wood has its own rate of presence of structural moisture. Liquid elimination is slow, so drying can take months or years in a normal environment.
Wood is divided into three categories:
- Wet – relative moisture content is more than 23%.
- Semi-dry – moisture content 18–23%.
- Dry – moisture content value 6–18%.
Indicators of moisture content of lumber for different types of work
Depending on the purpose of the wooden blank, the material is dried in different ways. Wood is dried to 6–8% moisture content if it requires mechanical processing and collection of products for combination with high accuracy, affecting the level of use (skis, parquet, musical instruments).
Transport presence of moisture contains 18–22%. This presence of water in lumber corresponds to long transits during the warm season. Wood that has been dried to such a moisture content is most often used in building a house, making containers, or if there is no need for interchangeability during installation.
Carpentry dampness has subspecies. Molded materials include deck boards, cladding, floorboard, whose humidity should be 15%. Lumber products, such as doors, windows, stairs, made from solid or glued material, tolerate 8–15% humidity.
Furniture humidity, depending on the degree of the product and the use of solid or glued material, is 8%. It is at this humidity that wood exhibits optimal qualities for finishing, gluing, and subsequent use. Basically, the moisture content is reduced to 7–10% with partial disinfection of the wood and taking into account the regularity of moisture throughout the material, maintaining the mechanical qualities of the board, and the absence of cracks forming outside and inside the lumber.
Features of drying chambers
Industries that process wood process up to 1 thousand cubic meters every year. lumber. Main role In this process, the drying chamber plays a role, which provides the material with the necessary quality.
Drying equipment is used to quickly dry wood, which makes it possible to prepare high-quality products and immediately send them for further processing. Boards that dry out on their own can delay production for weeks and sometimes months. In addition, such material may have defects and shortcomings that are unacceptable in wide production.
Factories that manufacture wood drying chambers provide full service to their customers. They design modern chamber dryers and professionally install equipment, launch it, set it up and provide service.
When manufacturing a drying chamber, specialists calculate the acceptable volume and number of chambers, providing customers big choice equipment for various needs. Chambers for drying wood are produced with a volume of 30–300 cubic meters. m and more. In addition, equipment may differ in the type of chamber loading and warming method. The most popular are chambers that are heated by water, steam, or electricity.
Advantages of designs
The advantages of drying chambers that are made to order include:
- design and creation drying plants according to the required volume and needs of the buyer;
- production of drying equipment made of aluminum and stainless steel;
- remote control of material drying using the Internet.
The lumber dryer has modern ventilation equipment, which is equipped with fans from German and Italian manufacturers. Installation, startup and configuration of the device is carried out at a professional level.
Which drying chambers for lumber are better?
In industry, various methods of drying timber are used for wood processing. These are atmospheric, chamber drying, contact drying, drying in liquids, as well as induction, rotational, radiation and PAP drying.
The required energy in convective drying equipment is transferred to wood using the air circulation, and the necessary heat transfer to the material comes through convention.
Camera types
There are 2 types of convection chambers - tunnel dryers and chamber dryers.
Tunnel dryer is a deep chamber into which piles of stacks are pushed from the wet end to the dry end.
Such chambers must necessarily be filled at one end and empty at the other. The process of pushing stacks is carried out 1 piece at a time, the interval between each is 4–12 hours. They are used by large sawmills, they only perform transport drying of lumber.
Chamber installation most commonly used in industry. The process takes place in a gaseous environment. This is heated air or superheated steam at atmospheric pressure. Drying in such equipment is carried out regardless of climatic and atmospheric conditions. The entire process is controlled, allowing the production of material with different final moisture content.
Atmospheric drying of hardwood takes place in an open warehouse or under a canopy. At low temperatures, the air has little ability to absorb moisture vapor, so it passes slowly, and in winter it may stop. This method is used to dry exported lumber at factories that ship the material during the season.
According to the method of circulation, there are chambers that have incentive and natural circulation. The wood drying chamber with natural circulation is outdated and ineffective.
The drying mode in them is practically not regulated, and the rate of uniform drying of lumber is unsatisfactory. Such drying is not recommended for modern construction.
Making a drying chamber for lumber with your own hands
To make a drying chamber yourself, you first need to select the material for the frame. Most often used metal racks from the corner either, and also needed wooden beams, treated with an antiseptic. The walls are covered with metal sheets, moisture-resistant plywood panels, and profiled rolled products. Thermal insulation is carried out using polystyrene foam and mineral moisture-resistant wool.
Before construction, the location of the dryer is determined in order to make a concrete foundation. The foundation is necessary so that the structure is stable and the load on the ground is evenly distributed.
The frame is assembled by welding or bolted connections. Then you should sheathe the walls from the inside, insert doors and windows. The layer of thermal insulation on the floor should be at least 12–15 cm. Then you need to check the chamber for leaks by placing a powerful fan heater with the hot air directed parallel to the boards.
Drying the boards is necessary to obtain high-quality raw materials. After all, building a house using damp lumber will lead to distortions and damage to its integrity. Therefore, it is important to take the elimination seriously excess moisture made of wood.
Video: DIY drying
Any woodworking enterprise cannot do without such a procedure as wood drying. And to prevent defects from appearing in the process, a special drying chamber for lumber should be used. Such a dryer will also be useful for those who produce wood products at home; in such cases, you can make it yourself.
Drying value for wood
Wood for making various products must first be dried so that it is suitable for subsequent use. So, if your furniture is made from wood that is too wet, it will quickly dry out and become unusable. And if the wood is too dry, then, for example, the door will quickly swell and will not close.
Drying wood is also useful for the following reasons:
- the material is protected from fungal attack;
- a change in size and shape is prevented;
- the mechanical and physical properties of the material are improved.
Drying is a long process, the wood is heated by hot air or superheated steam. After drying, the wood can be stored and transported longer, it will not be subject to deformation.
Drying chamber for lumber
Kiln drying is a key way to dry wood. Dryers are used to dry deciduous and coniferous wood until different types quality. The most common and economical drying method is as follows. Free and bound moisture is removed from the tree by supplying wet wood heat using hot air. Next, excess evaporated moisture is removed using humidified and partially cooled air.
The drying chamber is entirely ready installation, equipped with all the necessary equipment for work. By design, such chambers can be prefabricated metal or assembled from building materials. The latter are manufactured directly in workshops or as free-standing buildings based on industrial materials.
The chamber can be entirely made of monolithic reinforced concrete, the walls can be lined with solid red bricks, and the ceiling can be reinforced concrete.
If several chambers are used in production, they can be combined into one block, which has a corridor with heat distribution and an automatic control system. Depending on the volume of loaded wood, air circulation can be horizontal-transverse or vertical-transverse.
Lumber can be loaded into the chamber on trolleys along a rail track or as packages using a forklift. Heat is transferred to wood in the following ways:
- through the air;
- through combustion products;
- using superheated steam;
- radiant heat;
- solid;
- through current;
- through an electromagnetic field.
Equipment for of this device can be basic or additional. The main ones include the following:
- fan system;
- heat supply system;
- humidification and supply and exhaust ventilation.
TO additional equipment relate:
- blocks (door, psychrometric and insulated);
- fan drive electric motor;
- stacking trolleys.
The drying control process can be automated, which helps maintain the temperature and humidity inside the chamber at a certain level. The temperature is regulated by supplying coolant to the heaters or by turning the electric heater on or off.
Humidity can be adjusted using a remote moisture meter, with which you can check the condition of the material remotely at several points at once. If there are no external sources of heat supply, then autonomous heating means running on electricity, coal, gas, lumber or diesel fuel can be used.
Classification of structures
In convection-type chambers, energy penetrates the wood through the air cycle, and heat transfer occurs through convection. Such structures can be tunnel or chamber.
Tunnel dryers are deep and push stacks of stacks from one end (wet) to the dry end. They are filled at one end and emptied at the other. The stacks are pushed one at a time every 4-12 hours. These dryers are used for large sawmills and help with transport drying.
Chamber dryers are shorter; during the drying process, the same parameters are maintained throughout the chamber. If the blowing depth is more than 2 meters, then in order to equalize the drying conditions, the method of reversing the ventilation direction is used. The chamber is filled and emptied on one side if there is only one door. Lumber can be dried in them any up to different humidity levels. These are the designs that are most often used in our country.
The condensation type of dryer is different in that the moisture that appears in the air begins to condense on special coolers, and then the liquid is removed. The efficiency here is high, but the cycle is long, since devices with high temperatures do not work and large heat losses are observed. These types of equipment are more suitable for processing small volumes of materials or drying dense wood - ash, beech or oak. But condensation chambers also have a number of advantages:
- no need for a boiler room;
- The cost of the camera and the cost of operation are low.
Drying chambers also differ in the method of circulation and the nature of the drying agent, the principle of operation and the type of enclosure.
For example, circulation can be natural or forced. Designs of the first type are outdated and inefficient, it is almost impossible to control the modes, and the uniformity of drying of the material leaves much to be desired. Given modern requirements, it is better not to use such dryers.
Depending on the nature of the drying agent, the chambers are:
- air;
- gas;
- high temperature.
Drying modes
Depending on the quality requirements, lumber is dried in a special apparatus in different modes, which differ from each other in temperature. If it is a mini chamber, then during the process the temperature slowly rises and the relative humidity of the agent decreases.
One mode or another is selected taking into account the following factors:
There are high-temperature and low-temperature process modes. In low temperature it is used as an agent wet air, the initial temperature is less than 100 degrees. There are three categories of these types of modes:
- soft - drying is carried out without defects, the mechanical and physical properties of the wood are preserved, including its color and strength;
- normal - drying is also carried out without defects, strength is preserved almost completely, color may vary slightly;
- forced - the strength to static bending, tension and compression is maintained, but the strength to chipping and splitting may decrease with darkening.
In high temperature conditions There is a two-stage change in the agent's performance; it is possible to move to the second stage from the first only when the wood reaches a transitional moisture content of 20 percent.
Such modes are assigned depending on the type and thickness of the tree, and are intended for drying materials used in the production of load-bearing structures of buildings and those products where it is possible to use dark wood with reduced strength.
Before starting work in one mode or another, the lumber must be heated with steam supplied through humidifying pipes with running fans, closed exhaust ducts and heating devices.
Be sure to calculate the lumber chamber. The temperature of the drying agent at the beginning of heating should be 5 degrees higher than the first stage of the mode, but not higher than 100 degrees. The level of environmental saturation for a material with an initial humidity of 25% is 0.98−1, and if the humidity is below this indicator, then 0.9−0.92, respectively.
Duration initial period depends on the type of wood. For conifers it is up to 1.5 hours for each centimeter of thickness. For soft hardwoods it will be 25 percent more, and for hardwoods it will be half more compared to softwoods.
After preheating, it is necessary to bring the performance of the drying agent to the first stage of the operating mode. Then the drying starts directly in compliance with the selected mode. Humidity and temperature can be adjusted using valves on steam lines or dampers in supply and exhaust ducts.
When an infrared dryer operates, residual stresses appear in materials, which can be removed through intermediate and final moisture and heat treatment in an environment high humidity and temperature. It is necessary to process lumber that is dried before operational indicators and then need machining.
Intermediate moisture-heat treatment must be performed during the transition from the second stage to the third, or from 1 to 2 when using high temperature. Coniferous species with a thickness of 60 mm or deciduous species with a thickness of 30 mm or more are subjected to this treatment. The ambient temperature should be 8 degrees higher than the second stage, but not more than 100 degrees, provided the saturation is 0.95−0.97.
When the final average moisture content of the material is reached, the final moisture-heat treatment can be performed. It is carried out at a temperature 8 degrees higher than the previous stage, but not higher than 100 degrees. Further, the tree needs to be kept in the chamber for another 2-3 hours at the parameters of the last stage of the mode and only then stop the work.
Making a drying chamber
If you are making wood products at home, then you will need to dry the material yourself. You can also make a dryer yourself, but you must comply with all work standards. To make it you will need:
- camera;
- heating device;
- fan;
- insulation.
One wall and ceiling of the chamber must be made of concrete, and the remaining walls will be made of wood and will need to be insulated. There will be several layers:
- Styrofoam;
- boards wrapped in foil.
Now you need to install the heating element, it can be in the form of batteries. Water can be supplied to them from the stove in heated form at a temperature of 60 to 95 degrees. It is best to ensure a continuous process circulation of water through water pumps in the heating element. You will also need to install a fan in the chamber, with which warm air will be distributed throughout the room.
It is imperative to provide a method for loading wood into the chamber. For example, it could be a rail cart. To regulate temperature and humidity in work area You need to install wet and dry thermometers. And also inside the dryer you need to install shelves to expand the work space.
During processing, sudden changes in temperature should not be allowed, otherwise the wood may crack or warp.
Work on the construction of the chamber must be carried out in compliance with fire safety requirements, so be sure to install fire extinguishers.
And instead of heating element can be used electric stove from two burners. The walls of the chamber can be insulated with wood shavings, and instead of foil, you can use penofol, which can well reflect heat from the surface of the walls. Drying in such a chamber is carried out for 1-2 weeks.
Thus, there are a large number of different modifications of wood drying chambers. One or another option should be chosen depending on the material itself and the expected results. And if we're talking about about the production of various wooden products at home, it’s easy to make a camera with your own hands.
At the very beginning of the process, the air has quite high humidity and low temperature. The higher the initial moisture content of the tree, the more moisture there should be in the air entering the chamber. This is necessary in order to prevent cracking of the material. As the rock dries, the air temperature is gradually increased, while the moisture content in it, on the contrary, is reduced.
There is a strict relationship between air humidity and moisture content in the material. It can be determined using a special device - a psychrometer, which is used to determine the humidity and temperature of the air in drying chambers. The latter are called sushila. There are various methods for drying wood.
The factory method involves the use of special drying chambers. These are periodic steam-air dryers with reverse circulation. The resulting material, unloaded from there, is kept in the production workshop for two to three days. At this time, the material is normalized, that is, it is released from surface and internal stresses acquired during the drying process.
There are also chambers for drying wood material. In such periodic devices, a special smokeless gas is used to get rid of unnecessary moisture.
It is obtained by burning raw wood waste in furnaces. With the help of a high-pressure axial fan, through special gas ducts, it is supplied to the stacks of lumber. The design of the system assumes the presence of a steam humidifier.
In the woodworking industry, gas devices operating on natural gas are used. They are equipped with a firebox, the temperature in which during combustion reaches 1300°C. But before entering the dryer, the mixture circulates and cools, acquiring a temperature of 100 degrees by the time it enters the chamber. The working mixture is smokeless. If the operation of such a chamber is well adjusted, then the lumber dried in it remains light. Each can accommodate four large stacks of boards. They are also used for regular, routine drying. coniferous species tree.
For speed drying building material Electric dryers are used, which use high-frequency currents. This procedure does not last long - the drying time is only a few hours, and its quality is high. The wood dries evenly: without flaws or cracks. The amount of defects with this drying method turns out to be significantly less than with the gas and steam methods - its figure is less than five percent.
Features of heating dielectrics and semiconductors (wood also belongs to them) in electric field high frequencies are that the temperature of the entire processed material increases noticeably in a short period of time. A wet board can be heated to 100 degrees throughout its entire thickness in three minutes. The power of current absorbed by the material is regulated by parameters electric field(by changing it through adjustment).
Home drying of wood
In addition to industrial methods of drying wood, there are also home ones.
Using a microwave
The advantages of this method are that when it is used, tiny cracks do not form in solid wood, which can turn up to one and a half centimeters of material from each end into waste, and in some cases even break the workpiece into pieces. Under the influence of microwave heating, changes occur in the lignin fibers, due to which an object dried in this way loses its sensitivity to sudden changes in humidity.
For the drying procedure, not too powerful is suitable, budget model microwaves without unnecessary options. The main thing is that she has a routine low power. Usually it corresponds to the “defrost” mark. The chamber must be large enough to accommodate crafts or wooden pieces. Often the width of the chamber is big sizes than in depth.
Microwave drying of wood: technology
It is more convenient to dry individual pieces entirely; some are better cut into pieces. If it is already known what they are intended for, then they are cut to the size of future products, with an allowance. It is allowed to dry a pre-processed workpiece, which must also have at least a small allowance. It should be remembered that the product may become deformed during the drying process. A round object can become more oval.
Anyone who often works with wood gradually gains experience. Craftsmen can guess what kind of reaction to expect from which type of wood, how exactly which type is deformed, and make the appropriate allowance. If you leave a processed raw piece on the table, it may burst.
During breaks in work (for example, when carving) or before drying in the microwave, it is necessary to put the product in a plastic bag.
Microwave: drying at home
Before starting the procedure, the workpiece is weighed and the weight is recorded. Wrapped in plastic bag with the holes made, the item is placed in the middle of the oven and exposed minimum power. Processing time depends on the size of the item. Then the workpiece is cooled directly in the bag and warmed up again. The condensate from the bag is drained and the item is weighed.
The entire cycle is repeated several times until the mass becomes constant and stops decreasing.
If the item cracks in the first attempt, it is necessary to either reduce the power further or seal the ends of the workpiece. The mouthguards are wrapped in newspapers before being placed in the bag. You can also do this with other workpieces: this will reduce the likelihood of wood cracking.
After cooling, before the next cycle, the newspapers are replaced with new ones. If present in the array resin pockets, the latter can boil, tear it apart, and stain the stove with resin. Wrapping in paper will also help here.
If you continue the process of heating already dried wood, it can char and even catch fire.
Natural air drying of wood
This is an affordable and extremely simple method. The boards are stacked under a canopy to prevent precipitation and sunlight from falling on them. A special one must be prepared for them. level base, for the equipment of which you can use rails, logs, thick pipes or bars. Lumber is laid across this base.
There should be a distance of 0.3 m between the ground and the bottom layer of boards. It is better to cover the ground under the stack with sheets of roofing material, straw or hay. The wood takes quite a long time to dry: this process can take up to several years. In warm weather, the process is more active.
The ends of the forest are covered with a special mixture containing lime. The sides of the stack are protected from slanting rain and strong winds. Special measures are taken to prevent rapid drying and cracking of the material. Spacers are laid across the boards, between the layers of dried wood, at a distance of a meter from each other: the outermost ones are located flush with the ends of the boards in the stack.
With this method of drying wood with your own hands, mandatory cracks form at the ends of the boards. For this reason, the length of the blanks should be slightly longer than the planned products. After all, after drying is complete, the cracked ends of the boards will have to be cut down. With such drying, carried out in dry and warm conditions, the remaining in - is the largest online store selling furniture, lamps, interior decor and other goods for a beautiful and cozy home.
Classification of types and methods of drying wood:
convective wood drying technology;
conductive wood drying technology;
radiation technology for wood drying;
electric wood drying technology.
Each type of drying can also have several varieties depending on the type of drying agent and the characteristics of the equipment used for drying wood.
There are also combined technologies for drying wood, in which they simultaneously use different kinds heat transfer (for example, convective-dielectric) or combine other features of various wood drying technologies.
Convective wood drying technology
Chamber drying of wood is the main industrial technology drying of wood, carried out in wood drying chambers various designs, where lumber is loaded in stacks. Drying occurs in a gaseous medium (air, flue gases, superheated steam), which transfers heat to the wood by convection. To heat and circulate the drying agent, drying chambers are equipped with heating and circulation devices.
With chamber wood drying technology, the drying time for lumber is relatively short (from tens of hours to several days), the wood dries to any given final moisture content at the required quality, the drying process can be reliably regulated
Atmospheric wood drying technology
- the second most important and widespread method of industrial drying of wood at sawmills, carried out in stacks placed in a special open area (warehouses), washed atmospheric air without heating. 
The advantage of atmospheric wood drying technology is its relatively low cost.
Disadvantages of atmospheric wood drying:
seasonality (drying practically stops in winter);
long duration;
high final humidity.
Atmospheric wood drying technology is used mainly for drying lumber at sawmills to transport moisture and at some woodworking enterprises for drying and leveling the initial moisture content of lumber before drying in wood drying chambers.
Technology of drying wood in liquids - carried out in baths filled with a hydrophobic liquid (petrolatum, oil) heated to 105...120 °C. Intensive transfer of heat from liquid to wood makes it possible to reduce the drying time by 3...4 times compared to chamber drying, all other things being equal.
This method is used in wood preservation technology to reduce its moisture content before impregnation. Attempts to dry lumber in petrolatum at woodworking enterprises have not yielded positive results due to the fact that lumber after such drying does not meet the requirements for wood for furniture and joinery and construction products.
Conductive (contact) wood drying technology is carried out by transferring heat to the material through thermal conductivity upon contact with heated surfaces. It is used in small quantities for drying thin wood materials - veneer, plywood. 
Radiation technology for wood drying - occurs when heat is transferred to a material by radiation from heated bodies. The effectiveness of radiation drying is determined by the flux density of infrared rays and their permeability in solid wet bodies. The intensity of the radiant energy flow weakens as it goes deeper into the material. Wood is a low-permeable material for infrared radiation (penetration depth 3...7 mm), therefore this method is not used for drying lumber. It can be used for drying thin-sheet materials (veneer, plywood), in addition, this method is widely used in the technology of finishing wood products for drying paint and varnish coatings.
Electric stoves, electric heating elements, gas (flameless) burners, and incandescent lighting lamps with a power of 500 W and above are used as emitters.
Rotational wood drying technology is based on the use of the centrifugal effect, due to which free moisture is removed from the wood when it is rotated in centrifuges. Mechanical removal free moisture is achieved at a centripetal acceleration value of at least 100...500g (g - acceleration free fall). Such accelerations have not yet been achieved in practice due to the difficulty of accurately balancing a centrifuge with a stack; only experimental development of corresponding devices is underway.
In well-known industrial rotary dryers centripetal acceleration does not exceed 12g. Under these conditions, mechanical dehydration occurs to a small extent. However, intensification of the drying process in the humidity range above the hygroscopic limit is observed.
When installing a carousel in a drying chamber, the technology for drying lumber is the same as in conventional batch chambers. The duration of drying at the first stage (from the initial moisture content to the hygroscopic limit) is reduced several times depending on the thickness, species and initial moisture content of the wood compared to conventional convective drying under the same conditions. Although rotary dryers are economical and provide high quality drying, industrial use I have not yet found a rotational method for drying lumber.
Vacuum wood drying technology - drying under reduced pressure in special sealed drying chambers. Due to the complexity of the equipment and the impossibility of obtaining low final moisture content of wood vacuum drying has no independent meaning. It is used in combination with other drying methods and as an auxiliary operation in preparing wood for impregnation.
Dielectric wood drying technology
- drying wood in an electromagnetic field of high frequency currents, in which wood is heated due to dielectric losses. Due to the uniform heating of wood throughout its entire volume, the emergence of a positive temperature gradient and overpressure inside it, the duration of dielectric drying is tens of times less than convective drying. Due to the complexity of the equipment, high energy consumption and insufficient quality of drying, dielectric drying itself is not widely used. 
It is necessary to dry wood in 2 stages. The first stage is pre-drying. It involves storing wood in stacks under a canopy. Thus, drying is carried out naturally, although this process takes several years. But under no circumstances should this stage be skipped, because without it the wood will tend to sag and will be fragile.
The second stage is to dry the wood in vacuum chamber. There should be a low air temperature, which prevents internal stress from increasing and helps in gentle drying of the material. Currently, the drying process is controlled by a computer. It takes into account all the characteristics of wood of a certain species and issues reports on drying at all stages.
When drying wood, it is necessary to maintain room humidity of no more than 12%. Next, the wood is placed in a closed room, where its moisture content is balanced until the final result is achieved, and only then the material is ready for use.
DIY lumber dryer
The drying process of wood takes place in several stages. Initially, moisture evaporates from the surface of the wood, and then the moisture inside evaporates. First, its thinner parts dry out, and moisture begins to move from thickening to thin places. Therefore, as a result of improper drying, the thinner layers of wood begin to shrink. As a result, the wood warps or cracks.
Wood warping or cracking
To prevent wood blanks from warping or deteriorating during drying, they are treated with a special mixture. To obtain it, take crushed and sifted chalk and drying oil. The ingredients are mixed by adding chalk to the drying oil until the consistency of thick sour cream is formed. The end sections of the workpieces are painted with this mixture.
Therefore, wood should be harvested in the form of boards, beams or other equilateral geometric shapes. Stumps, ridges and other parts of plants intended for three-dimensional sculptures, dishes and other things should be processed immediately after cutting, when the wood is still raw and therefore easier to process with cutting, sawing and slotting tools and devices.
To speed up the drying process of wood, it needs to be steamed. To do this, place the raw wood in a vat of a suitable size, pour in a small amount of water and place the tightly closed vat in the oven of a well-heated oven.
Wood that has undergone this treatment resists cracking and acquires a deep brownish-golden color.
To dry wooden blanks intended for carving, you can use a canopy, attic, or balcony. However, the master carver should remember that wood stacked takes longer to dry, while wood stacked vertically takes longer to dry. But the latter type of drying sometimes gives unwanted bends and deformations to the workpieces, or unwanted cracks and splits form on the wood. In this case, it is better to saw or chop the wood blank along a ridge or crack and dry it in parts.
Ridge. Trunk. Camel.
If the craftsman subsequently has to make a wooden product from a trunk or ridge, resorting to sampling its core, then drying such a workpiece is best done by selecting (drilling) its inner part in advance. Wood blanks without a core will dry evenly and become deformed during the drying process.
It is best to dry the wood by laying it on a cement base or floor. Cement absorbs moisture over the entire surface of the wood, so the workpieces do not deform. To ensure that the wood dries evenly, you only need to periodically turn it from side to side.
Wood blanks for making carved wooden products or structures can be made with or without bark. It all depends on the type of product and the creativity of the master. It should be remembered that long-term storage in the bark of birch, aspen, beech, poplar leads to their deterioration and the formation of rot. Therefore, not every type of deciduous wood can be harvested for future use and stored “in clothes”, i.e. in the cortex.
Different types of wood dry differently. Each requires its own period of time to dry. This depends on the humidity, hardness and density of the rock, the size of the workpiece, the presence or absence of bark and other parameters. Knotty wood dries faster.
During drying, hardwoods are more likely than hardwoods to crack and tear fibers. This is because the sapwood of hardwood is soft and delicate, while the heartwood is harder. It is the sapwood that first becomes unusable. Therefore, if necessary, it should be removed from the surface of the workpiece before drying, and in order wood harvesting dried evenly and did not deteriorate; it is better to cover the ends of the cuts or cuts with putty.
To preserve wood that has a core, you need to remember that when it dries, the sapwood adjacent to the core cracks first. external parties to the core. It is cut off with an ax and lubricated at the ends with special putty.
Unwanted cracks and ripples that appeared on the wood blank during the drying process can be puttied. For these purposes, use putty purchased from retail outlets or home-cooked.
To prepare the putty, you will need glue, oil paint or varnish residue, to which well-sifted fine sawdust or wood dust is added. The component parts are mixed and the resulting mixture is used to fill cracks, crevices, and cracks.
To determine how dry the wood blank is, it should be applied to your lips. The heat emanating from it indicates its readiness and complete drying. Tapping your knuckles until you hear a clear, ringing sound, also indicates the readiness of the wood. Wet wood is easy to cut and plan, and the tool leaves a wet mark on its surface.
For more precise definition To determine the drying quality of a particular type or type of wood, use a special device - an electric moisture meter.
electromoisture meter
These methods of air (atmospheric) drying are the simplest and have long been known to master carvers. However, you can dry the wood or workpiece in another way. This means drying it in drying chambers.
Another “ancient way” of drying wood is drying it in shavings, when the workpiece is covered with a layer of wood shavings. The result is uniformly dried wood without cracks or other defects.
Finished products can be dried in sand. The product is placed in a container of suitable size and sprinkled with clean river sand. Without covering the container with a lid, place it in the oven. It is important that the edges of the product do not come into contact with the walls, then the decorative effect after drying will be of optimal quality.
Steaming wood blanks in a water-chip mixture in a Russian oven is another ancient method used by architects and master carvers.
If for any reason the wood blank is dry and its processing is difficult or impossible for the carver, it should first be soaked in water. Wet wood will allow you to perform any operations with it: bending, cutting or sawing.
Store prepared and dried wooden blanks, intended for carving, in a covered and warm room where the same air temperature is constantly maintained.
How correctly and competently they dry 
Ivanovo lumber depends on its quality and shelf life. To protect wood from moisture, bark beetles and other external factors that can harm the material, a home-made lumber dryer is perfect.
The quality and reliability of wood raw materials will increase significantly if it is dried correctly. Properly dried wood will allow you to get the job done quickly and easily. The process of creating a home dryer can take more than one week, so it is better to prepare for it in advance.
Let's consider the main stages of construction.
1. The area can be used in the middle land plot or on the roof if it is level. We cover the floor of the dryer with already used roofing material residues, sprinkling the layers with sawdust to avoid sticking. 
2. Wood material spreads in a stack across the air currents of the wind. The stack should not exceed 1.2 m, and the most the best option its duration is 0.8 m. The thickness of the stack should be at least 0.5 m, and best of all 0.7 m.
3. To build a stand for the stack, you will need to build a well of wooden beams with a length of about 0.5 m and a cross-section of 50x50 mm. We stack two such wells, 0.7 m each, and lay a layer on top with a cross-section of 60x80 mm. There should be a distance between the wells equal to the length of the stack. The layers on which the wood will be laid must have the same level and be no thinner than 2 cm. It is best to make layers by planing them.
4. The very bottom and top layers of the stack are pulled together with a rubber band. It turns out that the stack will be pulled together in height. The easiest way to make a rubber band is from an old unnecessary tube, dissolving it into strips of 30-40 mm.
5. We create protection from wet precipitation. The stacks should be covered so that any trapped moisture can then evaporate. If this option is not possible, then it is better not to cover it at all. We place dry wooden beams on the top layer, on them iron sheet, and the bars are placed on the canvas again, creating an air chamber. Leave iron overlaps at the edges of 15-25 mm.
Drying lumber for wood quality
Lumber is the result of sawing logs along the grain. In other words, these are boards, slats, 
bars and so on. When building or finishing a home, only dry lumber is used, since raw wood does not have the required qualities. Drying lumber is the process of removing moisture from wood until required percentage humidity. This procedure is carried out to improve the quality of its physical and mechanical properties.
1 Drying lumber - determining the moisture content of the wood
Before drying lumber, it is necessary to check its moisture content, because dehydration may not be necessary. The most common methods for determining wood moisture content are electrical and gravimetric. Electric way will require the use of a special device - a moisture meter. By passing an electric current through the wood, it determines its ohmic resistance, which depends on its humidity.
When determining humidity by weight, a small part is sawn off from the board, weighed and placed in drying cabinet, where it is at a temperature of 105 ° C. After a complete cycle, the test part is weighed and the measurement results are compared.
Excessive moisture in lumber causes early wear wooden buildings, formation of fungus and mold. Such wood is poorly processed, and during the shrinkage process it warps and cracks. Wood that is too dry will absorb moisture and swell, which will also lead to its deformation.
2 Technology of drying lumber - methods of carrying out the operation
There are various methods of wood processing, but the most accessible and widespread are atmospheric and chamber technologies for drying lumber. Below we briefly describe the features of each approach. During atmospheric drying, the tree is in the open air or under a canopy. This type of processing proceeds very slowly, since at low temperatures there is almost no release of moisture, and in winter this process practically stops.
Atmospheric drying is sometimes used before chamber drying. Special rooms for wood processing, where heated air or steam is used for dehydration, are called drying chambers. This technology does not depend on weather conditions, and also allows you to obtain kiln-dried lumber with a given moisture content.
3 Drying boards - we build it ourselves 
A do-it-yourself lumber dryer is a rather troublesome thing to build, so you need to carefully prepare for construction. The type of wood and the thickness of the board being dried have great importance. Homemade camera will quickly recoup all costs, since dried lumber is more expensive than raw lumber.
A board dryer, like any other building, begins to be built from the foundation. It can be any area, but the structure small size will be more cost-effective, that is, building several small chambers will be much more economical than one large one.
The frame is assembled from aluminum profile, since this metal is not subject to corrosion. The frame is then sutured aluminum sheets, to which thermal insulation with a thickness of at least 10 cm is attached. Fire-resistant and elastic insulation is required.
A lumber dryer should be airtight and allow humidity, temperature and air circulation to be controlled. The floor is covered with roofing felt and sprinkled with sawdust on top. Next, you should lay out the boards to be dried in narrow (1-1.5 m) stacks. The height of the stack can be any, depending on the height of the room. Between the rows of lumber you need to place spacer bars.
The most economical and easy to operate are drying chambers for lumber with forced circulation air. With the help of fans, warm air is forced through the stack, laid across the air flow.
Modern convective drying technology
When designing a product, the designer competently determines the dimensions and tolerance ranges of all parts. The task of the technological service is to obtain the required dimensions and ensure their consistency over time. This is achieved through high-quality drying of wood.
Due to poor drying of wood as a raw material, it is impossible to achieve high quality, durability and reliability of finished products. Modification of sizes wooden structures observed almost always, whether we are talking about the construction of building frames, lining walls with clapboards, the manufacture of joinery or joinery and construction moldings. Is no exception furniture manufacturing.
The convective drying method is most widely used in industry. It involves heating the material to be dried by means of a drying agent using the thermal energy of steam, hot water or electrical energy.
Let's consider the technology of convective drying from the final point of view of the quality of dried wood, since it is not enough to have a good dryer, you also need to be able to use it correctly. The ultimate goal is to provide high-quality wood drying at a minimum cost.
One of the most important conditions To guarantee proper operation of drying chambers and high quality of drying, is the correct stacking of lumber. When laying, the following must be provided:
mechanical strength of the stack;
stability of its shape and the lumber laid in it;
uniform washing of all boards with a circulating drying agent.
With proper stacking, the percentage of defects from warping is significantly reduced and the uniformity of drying of lumber in the stack is improved.
The stacking base must be strong and rigid, the top of the base must be horizontal. Its length should be equal to the length of the stack.
Horizontal rows of lumber in packages or stacks must be separated by spacers. The number of spacers along the length of a package or stack is set depending on the type of wood, thickness and length of the lumber being stacked.
Inter-row spacers should be given Special attention. Gaskets are made from coniferous and deciduous wood that is free from rot and blue stains.
The gaskets must be planed and must have a certain section. During the drying process, repeated swelling and shrinkage cause the gaskets to become unusable. According to scientific and technical literature, the turnover rate of simple gaskets is 13.6 times, and of impregnated ones - up to 80 times.
Why is it necessary to plan gaskets? It turns out that this type of wood defect, such as the formation of surface and internal cracks in the dried material, is, other things being equal, proportionally related to the surface roughness of the inter-row spacers. This type of defect is typical for the lower layers of a high stack laid on unplaned spacers. Volumetric shrinkage of wood is 12 - 15% in cross section, and these are significant linear dimensions, especially for wide board. If the surface of the inter-row spacer is not smooth, then its protrusions prevent displacement during drying, which leads to the creation of such internal stresses that external and internal ruptures of the wood are formed in the corresponding places.
At serious attitude For drying, the stack is formed according to a stationary template; in mass production, using an automatic stacker.
Lumber, stacked in accordance with the above recommendations, is loaded into the drying chamber. In the case of front loading, the packages are placed in the chamber with a gap of 100-300 mm. It is not allowed to load stacks of incomplete dimensions into the chamber, or to operate the chamber with an incomplete number of stacks.
Moisture meter (moisture meter) sensors are installed in a stack of lumber in places of intensive and slow drying, embedded in the wood across the grain at a distance of 500-1000 mm from the end of the stack. Places of intensive drying are the outer boards and the top of the stack; slow drying - center and bottom. After installing the sensors, you should check the moisture meter readings. If there is a strong deviation in the readings of one of the sensors, it is necessary to reinstall it, moving away from the original installation site by 100-200 mm
Selecting a drying mode
The drying mode is a schedule of parameters of the drying agent, coordinated by time or by the condition of the material.
The drying modes are designed in such a way that when the moisture content of the wood being dried decreases, the rigidity of the drying agent parameters increases (the temperature increases, the degree of saturation decreases). This nature of the change in the parameters of the drying agent is due to the peculiarities of the development of internal stresses in wood and the requirement to maintain the integrity of the dried boards and workpieces.
To select a drying mode, you should decide on:
purpose of the dried material;
quality category;
regime category;
final humidity.
1. Drying quality categories
Depending on the purpose of the dried lumber, four categories of drying quality are established. Drying quality categories I, II, III provide for drying finished products to operating humidity, and they must ensure:
Category I - the possibility of machining and assembling parts in accordance with GOST 6449.1-82 for high-precision components products (some mechanical connections keyboard instruments, precision engineering and instrument making, laminated wood construction bearing structures, production of models, skis, etc.);
II category - machining and assembly of parts in accordance with GOST 6449.1-82 for critical components of products (furniture production, cases for radio and television equipment, keyboard instrument cases, joinery and construction products, building enclosing structures, passenger car and automobile construction, etc.);
Category III - mechanical processing and assembly of parts in accordance with GOST 6449.1-82 for less critical components of products (molded joinery and construction products, freight car building, agricultural machine building, ordinary containers, etc.).
Category 0 - drying of lumber for export and domestic consumption to transport moisture content, without reducing the strength or changing the color of the wood.
2. Categories of drying modes
Depending on the requirements for the quality of wood and the possibility of an external heating network, lumber can be dried in modes of various categories according to the level of the temperature field. A rational drying regime will be the use of which will ensure the shortest duration of the process while maintaining its safety and maintaining the strength and other natural properties of wood to a given degree. For low-temperature processes, there are mainly two categories of modes: soft and normal.
Soft modes that ensure defect-free drying of lumber while fully preserving the natural physical and mechanical properties of wood, including its strength, color and state of resin. Recommended for drying wood of quality category I, intended for export, when drying to transport humidity, with increased requirements for the strength characteristics of wood.
Normal modes that ensure defect-free drying of lumber with almost complete preservation of the strength characteristics of the wood with possible slight changes in its color. Recommended for drying in quality categories II and III.
3. Final humidity.
Wood tends to inevitably acquire the so-called equilibrium moisture content, which it tends to achieve during prolonged contact with the surrounding air. This necessitates the need to select the final moisture content of wood drying depending on its functional purpose (for furniture, internal doors And internal lining- within 7-9%, for windows and external doors - within 10-12%, for planed lumber or joinery and construction moldings - within 15%). The so-called transport humidity should be in the range of 16-22%.
The air temperature in the chamber is controlled by measuring and regulating the dry bulb temperature tc (supplying coolant to the heat exchangers).
During the entire wood drying process, the direction of air flow relative to the stack changes at regular intervals by reversing the electric drive of the fan(s).
Air humidity in the chamber is adjustable supply and exhaust ventilation and humidification system, after measuring the relative air humidity W(%) or the psychrometric difference dt (°C).
The process of drying wood in a drying chamber is divided into several stages:
1. Preheating the chamber;
2. Initial heating of wood;
3. Actually drying the wood;
4. Moisture and heat treatment;
5. Air conditioning;
6. Cooling.
1. Pre-heating the chamber
To prevent moisture condensation on the internal surfaces of walls and metal parts of equipment, the chamber enclosures must be heated to a temperature of 40°C.
2. Initial heating of wood
First technological operation After loading the stack, the wood itself is heated. During heating, water (steam) is supplied to the drying space through humidifying pipes with heat exchangers turned on, fans running and supply and exhaust ducts closed.
The temperature of the environment when heating lumber is maintained depending on the selected drying mode. The values of relative humidity and psychrometric difference are maintained according to the regime.
3. Drying wood
The drying of wood itself is divided into stages depending on the initial moisture content of the wood. As the wood moisture content decreases, the air temperature in the chamber increases and the air humidity decreases.
The initial moisture content of lumber is measured with a moisture meter at a positive wood temperature. Depending on this humidity, the initial stage of drying itself is determined from the regime table. It should be noted that drying is carried out on the wettest material.
If there is a moisture meter, its readings are used to judge the transition from stage to stage. In its absence, the drying process is carried out only by time. The drying itself ends when the final humidity is reached according to the data of all humidity sensors.
At this stage, as at the previous one, the following must be taken into account:
if the relative air humidity W is less and dt is greater than the regime one (the air in the chamber is drier), it is necessary to moisten the drying agent, for which the damper on the air duct should be closed, and if the air humidity does not increase to the specified value, water (steam) is supplied to the chamber ) through the humidification system;
if the relative air humidity W is greater than the specified one, and dt is less than the specified value (there is an increased moisture content in the chamber), the damper on the air duct must be opened, and humid air is removed from the chamber and at the same time fresh, drier air enters.
4. Moisture and heat treatment
Necessary for removing or reducing residual internal stresses in wood. It is carried out for lumber dried in the first and second categories of drying quality, as well as when drying hardwood and larch in any category.
There are final and intermediate moisture and heat treatment.
The final moisture-heat treatment is carried out when the average specified final moisture content of the wood has been reached according to all sensors. During moisture-heat treatment, water (steam) is supplied to the chamber through a humidification system with heat exchangers turned on, fans running and supply and exhaust ducts closed. The temperature of the environment during moisture-heat treatment is maintained depending on the selected drying mode. Relative humidity and psychrometric difference are maintained according to the regime.
Intermediate moisture-heat treatment is carried out during drying of lumber of increased thickness and hardwood. It is prescribed before moving to the last stage of wood drying itself. Environment settings are supported according to the selected mode.
5. Conditioning
It is carried out to equalize the wood moisture content across the volume of the stack and the thickness of the lumber. In the drying chamber, with the help of heat exchangers and a humidification system, an environmental condition is maintained in which under-dried assortments dry out, and over-dried assortments are moistened. The temperature of the environment during conditioning is maintained according to the mode.
For lumber of quality category I, conditioning treatment is mandatory. Its duration is approximately equal to the duration of the final moisture-heat treatment. For lumber of quality categories II and III, conditioning treatment is prescribed as needed in accordance with the results of monitoring the uniformity of final moisture content from previous dryings similar material. If you have a moisture meter, you should rely on its readings. 
Deviations in moisture content of individual assortments should not exceed the following values:
2% for quality category I;
?3% for quality category II;
?4% for quality category III;
?6%, ?4%, ?2.5%, respectively, for thicknesses up to 32 mm, 38-50, over 50 for quality category 0 (drying to transport humidity).
6. Cooling.
After leveling the final moisture content of the lumber, the stacks must be cooled to a temperature of 40°C, at closed door and open supply and exhaust ducts. In summer, fan(s) may be turned on.
What is "Infrared wood drying"?
Infrared wood drying is a radiation technology for extracting moisture from wood, which is based on the transfer of heat by radiation from the heated elements of the device. The power and efficiency of the technology is determined by the flux density of IR rays. Due to the nature of the effect, infrared drying of wood is applicable only for working with thin sheet materials (veneer, plywood) and for final finishing of wood products with paint coating outer surface. The basis of the system for infrared drying of wood is an electric film heater.
Lumber dryers
Price: 3000 rub/piece
Advantages of lumber dryers and areas of use.
The lumber dryer is used for drying wood located in a stack; it was developed by specialists from the Impulse company. The lumber dryer is a set of thermoactive cassettes, the thickness of which is 1.5 mm.
Advantages of the Flexichit infrared wood dryer:
Equipment for drying boards can be used both outdoors and indoors;
The dryer installation process does not take much time;
Saves energy as much as possible;
Makes it possible to dry small volumes of wood;
The use of cassettes for drying lumber meets all necessary quality standards, which makes it possible to achieve a moisture content in wood of no more than 8%.
The technology of drying lumber is a very responsible and labor-intensive process. The wood that has been prepared for drying must be stacked, and the cassettes must be placed in a certain sequence. To control the drying mode of boards, it is necessary to use a three-position thermostat, which sets the required temperature for the layers of the stack.
Design and principle of operation of a board dryer.
Wood dryer connection diagram
The technology used for drying boards is very simple; an infrared tubeless cassette dryer is used. Installation of the equipment is very simple, while the drying process itself meets all necessary standards. It is also possible to effectively and timely influence drying modes, consistent with the quality of the lumber.
Operating principle of a tubeless cassette dryer.
The principle of operation of a tubeless cassette board dryer is that the cassettes are stacked in a certain sequence. In order to achieve required humidity inside wood, with minimal energy consumption. It is advisable that the stack be covered with a special material with a reflective layer (foil) such as armofol. This is necessary so that the condensate that collects drains outside the stack.
The board dryer mode is controlled by a thermostat, which controls the temperature of the heaters. The drying time for wood depends on the wood used and the initial amount of moisture in it, as well as air humidity. This determines the time of the lumber drying process itself, which can range from three to seven days.
One of the most important factors for using the dryers we offer is that boards can be dried using small quantity lumber.
As mentioned earlier, installation of an infrared dryer for lumber does not take much time, but at the same time it is a complex set of equipment, the installation of which requires qualified specialists. The whole process is controlled automatically, but it also requires a certain order in preparation for work.
At the beginning of work, it is necessary to check the serviceability of the electrical circuit of the heaters, this is done using an ohmmeter, after which it is necessary to check the integrity of the outer shell of the heater. There should be no kinks, scratches or burns on the surface.
Work on connecting the heater must be carried out when the network is disconnected. Before turning on the dryer, the cassettes must be located in a certain sequence in a stack that is prepared for drying lumber. You can find video instructions for making one of the stack shell design options on our website.
Technical description of the dryer
the equipment operates from a 220V electrical network;
dimensions 1.25x0.62x0.0015 m;
power consumption 300-500W/m2;
weight no more than 10 kg/m2;
when following recommendations, the service life is at least three years;
electricity consumption per 1m3 1.5-2.5 kW;
class of protection against electric shock “1”.
wood drying technology
