For many centuries, humanity has been using wood as a building material and, despite the constant emergence of new ones, modern materials, popularity natural wood does not decrease at all.
How to choose the right lumber from a huge assortment? What causes the differences in price and quality?
Quality finished materials made from wood depends on many parameters - the type of wood and the quality of the original timber, the professionalism of the machine operators, compliance with the technology of drying lumber and the production of finished products. Another factor that has a significant impact on the quality and appearance lumber, as well as their mechanical properties, is the method of cutting wood that determines the texture of the board.
There are several types of wood cutting - tangential, radial, rustic and transverse, of which the first two are most widespread. To understand the difference between types of cuts, you need to have a good knowledge of the structure of wood and understand the technology of sawing wood.
In cross-cutting, wood is cut across the grain. The method is used in production artistic parquet. A rustic cut is any cut made at an acute angle to the direction of the grain. The method is used in the production of lumber for rustic flooring - the most heterogeneous and original in pattern and shade.
With a tangential cut, the cut plane runs tangentially to the annual layers of the tree at some distance from the core. Since wood fibers, as a rule, do not have a single direction, they create natural patterns on the surface of the board in the form of fancy “arches”, “curls”, “rings”. The texture of the resulting tangential cut board is uneven and may contain wood pores. Some of the dry boards may develop delaminations on the surface after finishing planing. After tangential cutting, the boards are characterized by higher coefficients of shrinkage and swelling, moreover, this scheme for sawing logs allows you to increase the coefficient useful output, which in turn leads to a reduction in the cost of the board.
For radial cut The cutting plane of the wood is perpendicular to the annual rings. With this method, the texture of the board is quite uniform with minimum distance between annual layers. This not only creates beautiful drawing, but also helps to increase the strength of lumber.
Radial cut boards have good resistance to external influences, have greater resistance to deformation and wear resistance than tangential cut boards.
The shrinkage and swelling coefficients of radially cut lumber are 0.18% and 0.2%, respectively, which is almost two times better than that of tangentially cut lumber. The reason for this phenomenon is that for radial cut boards, shrinkage and swelling occur along the thickness of the material, in contrast to tangential cut boards, in which dimensional changes occur along the width of the board. This explains the fact that in finished products (parquet boards, floor boards, block houses, imitation timber, lining) made from radially cut lumber, there are almost no gaps on the front surface, which is not excluded in products made from tangentially cut lumber. To obtain laminated veneer lumber by splicing wood without knots, blanks and boards of radial and semi-radial cuts are used, since the mechanical and geometric characteristics of the timber depend on the resistance of the fibers, which increases when gluing layers with multidirectional annual rings with an inclination angle of up to 45°.
The average useful yield of radial cut boards is only 10-15%. This explains their high cost. Radial cutting includes lamellas in which the angle between the annual rings and the blade is 60-90°. If the specified angle is in the range of 45-60°, such boards are classified as semi-radial cut. The best performance qualities has lumber in which the angle between the annual layers and the cutting plane is 80-90 degrees. Taking into account semi-radial cut boards, the useful yield coefficient can reach 30%.
Typically, when radial sawing, the log is initially sawn into quarters, and then from each quarter, boards are sawn off alternately from two layers. For sawing logs in a radial way, for example, UP-700 longitudinal sawing machines can be used. Important has a microprocessor control and optimization system UP-700, which is used by technologists to determine the percentage of yield of radial cut boards based on the criteria for optimizing the maximum yield finished products, as well as the conditions of radial and semi-radial cutting.
Comparing radial and tangential types of cuts, several conclusions can be drawn:
- Radial lumber has best properties shrinkage and swelling.
- Radial cut boards have the best mechanical characteristics and stability of geometric dimensions.
- The wood of radial cut boards has a uniform shade and uniform texture, which gives a special decorative value to finished wood products.
- Due to its characteristics, radial boards are more widely used, although they are more expensive.
The range of lumber offered is quite wide; woodworking products vary in quality, cost, as well as types of wood cutting. Let's take a closer look at what types of wood cutting exist, and for this we first look at general outline what exactly is the technology of cutting wood?
Forest cutting
First of all, the log is unraveled on a belt or disk sawmill, turning into a gun carriage. If all sides are sawn, then the output will be edged material, which is divided into timber, small timber and edged boards. Planed patronage is called lining, floorboard, platbands and baseboards. Glued products include, for example, furniture panels.
There are two main types of cutting wood (logs) into boards (lumber):
- radial;
- tangential,
as well as three additional types:
- mixed;
- semi-radial (rustic);
- central.
Types of board cuts
Radial cut- this is a cut in which the axis of the cut passes through the core of the log and, as a result, the lines of annual rings in the section of the board form an angle of 76 - 90 degrees. with its faces (two main planes of the board). The wood of radial cut boards is quite uniform in color and texture. Such boards practically do not deform when dried and do not swell when moistened, because the change in wood dimensions occurs mainly along the line of the rings (across the grain), and for radial cut boards they are located along the thickness. Radial cut lumber has the highest performance indicators compared to lumber of other types of cut.
Tangential cut- This is a cut that is made along tangents to the lines of the annual rings of the trunk at some distance from its core. The surfaces of such boards have a pronounced texture and a bright wave-like pattern of annual rings. For tangentially cut boards, the coefficients of shrinkage and swelling from moisture are twice as high as for radially cut boards, which causes their significant deformation when the humidity state changes. For this reason, tangential cut boards are less preferable for use in wet conditions than radial cut boards.
Rustic (semi-radial) and mixed cuts- these are cuts with signs of two main types of cuts at the same time: radial and tangential and, as a result, have indicators averaged between them. In a rustic cut, the lines of annual rings have the form of straight lines located at angles of 46 - 75 degrees. to the layers, and in a mixed cut these lines change from straight at the edges (along the width) of the board to arched in the middle.
Central cut- This is a cut made directly in the center of the trunk and including its core. Considering that the core of the trunk consists of the least durable wood, center-cut lumber has the most heterogeneous structure in terms of strength of all the types considered.
Features of the main types of cutting
At tangential cutting the cut plane runs tangentially to the annual layers of the tree at some distance from the core. Since wood fibers, as a rule, do not have a single direction, they create natural patterns on the surface of the board in the form of fancy “arches”, “curls”, “rings”. The texture of the resulting tangential cut board is uneven and may contain wood pores. Some of the dry boards may develop delaminations on the surface after finishing planing. After tangential cutting, boards are characterized by higher coefficients of shrinkage and swelling; moreover, such a scheme for sawing logs allows an increase in the useful yield, which in turn leads to a reduction in the cost of the board.
For radial cutting of wood, the cutting plane is located perpendicular to the annual rings. With this method, the texture of the board is quite uniform with a minimum distance between the annual layers. This not only creates a beautiful pattern, but also increases the strength of the lumber.
Boards radial cut They are distinguished by good resistance to external influences, have greater resistance to deformation and wear resistance than tangentially cut boards.
The shrinkage and swelling coefficients of radially cut lumber are 0.18% and 0.2%, respectively, which is almost two times better than that of tangentially cut lumber. The reason for this phenomenon is that for radial cut boards, shrinkage and swelling occur along the thickness of the material, in contrast to tangential cut boards, in which dimensional changes occur along the width of the board. This explains the fact that in finished products (parquet boards, floor boards, block houses, imitation timber, lining) made from radially cut lumber, there are almost no gaps on the front surface, which is not excluded in products made from tangentially cut lumber. To obtain laminated veneer lumber by splicing wood without knots, blanks and boards of radial and semi-radial cuts are used, since the mechanical and geometric characteristics of the timber depend on the resistance of the fibers, which increases when gluing layers with multidirectional annual rings with an inclination angle of up to 45°.
The average useful yield of radial cut boards is only 10-15%. This explains their high cost. Radial cutting includes lamellas in which the angle between the annual rings and the blade is 60-90°. If the specified angle is in the range of 45-60°, such boards are classified as semi-radial cut. The best performance properties are found in lumber in which the angle between the annual layers and the cutting plane is 80-90 degrees. Taking into account semi-radial cut boards, the useful yield coefficient can reach 30%.
Typically, when radial sawing, the log is initially sawn into quarters, and then from each quarter, boards are sawn off alternately from two layers. For sawing logs in a radial way, for example, UP-700 longitudinal sawing machines can be used. Of great importance is the UP-700 microprocessor control and optimization system, which is used by technologists to determine the percentage of yield of radial cut boards based on the criteria for optimizing the maximum yield of the finished product, as well as the conditions of radial and semi-radial cutting.
Comparing radial and tangential types of cuts, several conclusions can be drawn:
- Radial lumber has better shrinkage and swelling properties.
- Radial cut boards have better mechanical characteristics and dimensional stability.
- The wood of radial cut boards has a uniform shade and uniform texture, which gives a special decorative value to finished wood products.
- Due to their characteristics, radial boards are more widely used, although they have a higher price.
Main dimensions of lumber
There are standard dimensions of lumber. For example, the cross-section of a beam can be 10x10, 10x15 or 15x15 cm, and the length is 6 m. Deviation from these standards will require a special order and will also be associated with additional financial costs. The most expensive is profiled timber, manufactured to the highest cleanliness class.
The edged board can be 2.5 cm, 4 cm or 5 cm thick, 10 cm, 15 cm wide, and a standard length of 6 m. The length of small timber, in addition to the standard value of 6 m, can also be 3 m Its cross-section will be 4x4 cm or 5x5 cm. A by-product of the production of these lumber is a slab, on one side of which there is a face, and on the opposite side there is untreated wood.
Criteria for choosing lumber
Before you choose good lumber, the first step is to find out the type of wood being offered. It can vary from 4 to 0 depending on the number of knots and their quality. It is imperative to check the length of the lumber and the cross-sectional dimensions. If bends or rotational deformations are visible, then it is better to refrain from purchasing such products. You can check the evenness of the lumber by applying a stretched cord.
Wood defects- These are natural deficiencies of individual sections of wood, reducing its quality and limiting its use.
Defects are the defects of wood of mechanical origin that arise in it during the process of harvesting, transportation, sorting, stacking and mechanical processing.
One of the wood defects is fiber inclination- used to be called cross-layer. As is already clear from the name, this defect consists in the deviation of the fibers from the longitudinal axis of the trunk. The inclination of the fibers can be either tangential or radial.
Traction wood characterized by a change in structure in the extended zone of trunks and branches, manifested in a sharp increase in the width of the annual layers. Under the influence of light, such areas of wood are colored Brown color. As a rule, traction wood is typical for hardwood trees.
Curlyness- tortuous or random arrangement of wood fibers. Occurs in everyone tree species, more often in deciduous trees.
Curl- local curvature of annual layers near knots or shoots. It can be one-sided or through, reducing the strength of wood. The same " side effects"They also give ocelli - traces of dormant buds that have not developed into shoots. Their diameter does not exceed 5 mm. The ocelli are scattered and grouped, light and dark.
Pocket- density within or between annual layers, filled with resin or gums.
Core- a narrow central part of the trunk, consisting of loose tissue of brown or lighter color than the surrounding wood. At the ends of the assortment there are spots of about 5mm various shapes, on the radial surface - in the form of a narrow strip.
Displaced core- eccentric location of the core, accompanied by curliness.
Double core- the presence in the assortment of 2 or more cores with independent systems annual layers surrounded on the periphery by one common system.
Dry-sidedness- a section of the trunk surface that has become dead during the growth of the tree as a result of damage.
Sprouting- a healing or overgrown wound.
Cancer- a depression or swelling on the surface of a growing tree as a result of the activity of fungi or bacteria.
False core- a dark, unevenly colored zone, the border of which does not coincide with the annual layers, separated from the sapwood by a dark border.
Wood spotting- coloring of sapwood of deciduous trees in the form of spots and stripes, close in color to the color of the core.
Internal sapwood- adjacent annual layers located in the core zone, their color and properties are close to the color and properties of sapwood.
Water layer are called areas of core or mature wood with a high water content.
The hardness of wood primarily depends on the type of wood, and also to a large extent on the growth conditions of the tree, humidity, etc. Within one type, the spread of values can be quite significant. Averages are usually indicated relative indicators Brinell hardness as a percentage relative to oak, the relative hardness of oak is taken as 100%.
Strength is the ability of wood to resist destruction under mechanical loads. It depends on the direction of the acting load, the type of wood, density, humidity, the presence of defects and is characterized by its tensile strength - the stress at which the sample is destroyed.
There are main types of forces: tension, compression, bending, shearing.
Thus, when choosing materials and wood products, you should take into account the above characteristics and not purchase products with defects and defects in wood. As a rule, low-quality wood is not used for the production of products, but only your vigilance will help you avoid purchasing low-quality products that do not meet norms and standards.
Building materials made from hardwood and softwood have a wide range of applications; they are used for the construction and cladding of houses, paving paths, interior design building. The lumber on the market is divided according to the cutting method; it can be tangential, radial, longitudinal, disk or mixed. Depending on the presence of edges, boards are classified into edged, semi-edged and unedged.
Mechanical processing of logs can be carried out using special machines or electrical appliances by cutting or splitting. There are the following methods of cutting wood: planing, turning, drilling, grinding, all of which involve removing chips. There are three types of cutting - longitudinal, transverse and straight. The first involves cutting along the fibers, the second and third – perpendicularly. Sawing is the main stage in the manufacture of all lumber; the operational and aesthetic characteristics of the finished product depend on the quality of the procedure.
Tangential sawing
This method of processing logs is considered one of the most popular. With a tangential cut, the plane of the cutter passes at a certain distance from the core of the trunk, tangentially to the growth rings. The result is practical and durable boards that are resistant to shrinkage and swelling. Such lumber has an attractive texture - the graceful wave-like pattern of annual rings is clearly visible on them. Boards obtained by tangential cutting can be used for exterior decoration of buildings and creating a cozy interior.
High-quality parquet is also produced in this way. When cut perpendicularly, a natural pattern is visible on the boards - rings, arches, waves, curls. If the parquet is made of Siberian larch, it can be used for laying floors in rooms with high humidity, since products made from this rock, when in contact with water and steam, not only do not collapse, but also become stronger. Wooden flooring, created as a result of tangential sawing, will last for many years without needing repairs or renovations.
It is customary to call a radial cut of a log, carried out perpendicular to the annual layers. Lumber produced by this method has a uniform texture, they are characterized by increased strength and wear resistance, and are practically not subject to deformation. Radial cut boards have minimal shrinkage and swelling coefficients, so they do not collapse due to negative influence environment and are great for external cladding buildings. With this processing method, lumber has virtually no flaws. Defects may be caused by a violation of sawing technology (displaced core, incorrect size).
Radial sawing is used for the production of edged boards, a sought-after lumber used for finishing houses, summer houses and cottages. If the cladding is made of Siberian larch, it is perfectly would be better suited for decoration of baths, saunas and bathrooms. Products made from this coniferous species do not need additional processing, have an attractive texture and have a long service life. Edged board Widely used by interior designers, it can be used to create a cozy atmosphere in a room. Lumber from Siberian larch contains resin, when released, it spreads a pleasant aroma.
Mixed wood cutting
Semi-radial sawing is a common method of producing lumber. It involves cutting logs at an angle of 45°. This technology allows you to save raw material and reduce the cost of the finished product. The only drawback of this cutting method is that the resulting board may be subject to deformation due to improper drying. Therefore, special attention must be paid to preparing wood for processing.
Semi-radial sawn timber can be made from both hardwood and softwood. Products made from Siberian larch are especially popular today; their demand is due to their strength, resistance to mechanical damage and aesthetics. Coniferous cladding reliably protects the building from the effects of atmospheric phenomena, helps retain heat and create a comfortable microclimate indoors.
Equipment for cutting wood
For the production of lumber, modern high-tech equipment should be used, only in this case ready product will have a minimum of defects. The amount of waste generated when cutting wood also depends on the characteristics of the special equipment. Today, angle sawing machines are used for the production of boards, beams, and parquet; due to their special design, they make it possible to produce high-quality products and reduce the amount of waste. Using equipment for radial cutting, you can obtain not only radial, but also edged lumber. The basis for creating molded products is a log - a tree trunk freed from branches. Wood cutting can be done in various ways:
- at the sawmill;
- manually (using special sawing tools);
- on woodworking machines.
To use existing logs rationally, the craftsman needs to carefully study the sawing pattern (tangential, radial, longitudinal, mixed). Knowing how to distribute raw materials can reduce waste and significantly increase profits. For the production of wooden building materials at home suitable conditions manual method, which involves the use of chainsaws and hacksaws. However homemade boards and beams, as a rule, have defects and look unaesthetic. It is advisable to buy attractive lumber from specialized companies. Large enterprises carefully control the quality of their products.
You probably noticed that parquet boards have different patterns on the cut: even stripes or arbitrary, with a large number of lines and circles.
Radial cutting of wood - elite boards for select parquet
To get that same “striped” pattern, the log is sawn strictly along the radius. But radial cutting produces a lot of waste, so ready-made boards rise in price. In addition, the wood is less porous and therefore more wear-resistant, which also affects the cost. That's why radial cutting is considered elite.
Tangential cutting of wood - ordinary parquet boards
In production regular board the cutting plane runs at a distance from the center tangentially to the growth rings. This way you get more boards from one log, but the pattern will be unpredictable, with a lot of curls, lines, spots and rings. Wood looks more natural. Unlike radial cut boards, in this case the wood is more porous and less resistant to wear. Therefore, tangential cut parquet belongs to the economy class.
Thanks to modern technologies production, as well as special compounds for impregnation of parquet, the durability of tangentially cut wood increases.