What is a radial cut. Sawing lumber

lumber - materials from wood (beams, boards and bars) obtained by sawmilling. There are sawn timber of radial, tangential and mixed sawing. Lumber with sawn edges is called edged, with unsawn - unedged.

Large high-quality logs (these are logs from the bottom, butt of the tree) provide the most valuable lumber. When sawing such logs, it is necessary to determine the thickness of the resulting boards in order to maximize the volume and cost of the resulting material. Since lumber prices depend on its thickness, and in addition, when sawing into thick timber less sawdust is produced, this decision seriously affects income. However, if the quality of the thick material is lower, even if the best edge is almost clean, then sell it for good price it won't be easy. The sawmiller should try to reduce the size of the sawn material when he sees that the quality of the wood is starting to decline.

If the log is good, it is unwise to produce large lumber and railroad ties from the center of the log. Because the price of a bar is always less than the price of a board.

For logs of high grades sawing in a circle is recommended. In fact, sawing with respect to the taper of the log, with the log angled so that the cut is parallel to the bark, is recommended for all "good" edges. The result will be pure wood throughout the length, more valuable pieces of lumber, and this will avoid the need to saw the clean wood later into short pieces. When you get to the low grade part of the log, go to the shape of the cant and minimize the operation of cutting the cant on the sides.

Strong, but low-quality logs should be sawn as quickly as possible. These logs are of little use - the profit is very small, or none at all, which means that these logs need to be removed from the machine the sooner the better. Any method of sawing is suitable here. Most often they are sawn on a beam, or simply sawed through. In this case, it is generally better to reduce log flips to absolute zero.

Weak logs provide such insignificant profits and such a huge risk of breaking the product that it is better not to deal with them at all.

Medium quality logs can produce a significant amount of good lumber, and here a lot depends on the sawyer, on how he will turn the log. Here the decision to rotate the log is critical to profit.

First you need to choose the worst part of the log and cut it without taking into account the run. But you can not cut too much on this side. For small logs, in general, you need to cut one layer, that is, saw through the entire length of the log once, or a layer and a short board, and then turn the log over to the opposite side.

Another way is to choose the best side of the log and start sawing taking into account the taper of the log. Then it is this part that is sawn for a long time before the log is turned over.

Lumber is sawn from one side until the sawmill expects the next board on that side of the log to be at least as good as the boards that can be obtained from the other side. There is an exception: if you start sawing from the worst side of the log, then you have to cut until you get a completely smooth cut surface in order to turn the log onto it. In other words, good side logs need to be sawn deeply, and on the bad side, a layer or layer and one board are simply removed.

If we take a log with a diameter of 60 cm, although this is true for all logs of any size, when sawing with a 180 ° turn, we get 8 boards that need to be further cut on the sides, and using less effective method, always turning to the adjacent face, we get 13 such boards. This circumstance alone can already be a significant argument in favor of turning a log 180 °, especially for small enterprises. In addition, this way of sawing produces more wide boards, and they are usually more valuable. When flipping to the adjacent edge, 8 boards of tangential sawing are obtained, which are subject to strong warpage during drying. Further, if it is a walnut or red oak with a narrow sapwood, then with a 180-degree turn of the log we will get 10 boards with sapwood, with another method of turning - 13 boards. Sapwood causes problems with drying. And with a 180-degree turn of the log, the internal stress of the wood is removed, which as a result avoids cracks and cracks.

Turning over to the adjacent edge may be easier, but from an economic point of view and from the point of view of sawing safety, it is more beneficial to rotate the log by 180 °.

After sawing two opposite sides of the log, you need to move on to the third and fourth. As usual, the worst of these edges is sawn first, regardless of the taper of the log. However, the line good quality should always be sawn parallel to the bark to increase the yield of good lumber from the log.

The width of the first layer when sawing from all four sides of the log is critical.

If the edge is of good quality, that is, the first sawn board can be attributed to good grade, then the minimum width of the sawn lumber should be 15-1 cm. Of course, this depends on the size of the log itself. To allow for further processing of the board, planing or even trimming on the sides, it is recommended that 15-1 cm, not 15 cm.

If the edge is of poor quality, then it makes sense to cut boards with a width of at least 10-1 cm. The length of such boards should be at least 1.2 m. In general, you need to produce boards of no less length on your sawmill.

When it comes to logs of frankly poor quality, it makes sense to saw them from the “belly” or from the “ears”, and not look for a good edge. "Ears" are usually removed in 1 or 2 passes of the saw, exposing smooth surface inside the log. Sawing from the “belly” requires more manipulation, and as a result you get several short but clean boards.

The beam has a number of advantages in comparison with thin boards. The lumber often has a beautiful wood pattern that customers love. When drying, it dries out half as much as boards (3% versus 6% for boards). Less cracking during drying. When humidity changes environment beam is more stable. When they cover the floor, it hardly wears out.

Also, when sawing a beam, the exit useful product from a log 20% lower. Its production rate is much lower. It requires 15% more drying time. The beam dries out in thickness 2 times more than narrow boards. Sharp branches that remain in the timber, unlike round branches in boards, greatly reduce the strength of the material.

Radial called a cut, in which the cut plane passes through the core of the trunk. The wood of such boards is quite uniform in color and texture, the inter-ring dimensions are minimal. Radial sawn boards are resistant to external influences, practically do not undergo deformation and have high wear resistance. The radial sawn board has a shrinkage ratio = 0.19% and a swelling ratio = 0.2%. These figures for radial sawn lumber are twice as good as for tangential sawn boards. For a radial sawn board, the process of shrinkage and swelling goes along the width of the fibers - the thickness of the board, and for a tangential cut along the width of the board, because. the fibers at the "tangent" are arranged in width. Accordingly, at the floor board, parquet board, imitation of a beam, block house, lining of a radial cut, there are practically no gaps in comparison with similar products of a tangential cut. Since the output of radial sawn boards is 10 - 15% of the total volume, their cost is quite high.

Radial sawing of wood is a method of sawing a log in which all the fibers in the board go along the direction of the annual rings. When sawing radially, lumber has the best physical and mechanical properties. The strength and hardness of wood with a radial cut is higher than with a tangential cut.

The output of a radial sawn board is usually small (does not exceed 30%). On the UP-700 rip saws, the output of the radial sawn board reaches 60%. Such a high rate is achieved thanks to the cutting optimization system. Choosing among the optimization criteria the maximum exit of the board of the radial cut, the conditions of radiality and semi-radiality of the cut, the technologist determines the percentage of the exit of the radial board.

Radial sawing can be done on other equipment. But the percentage yield of a radial cut board on other equipment depends on how the operator cut the log. Usually this figure is much less than 50%. Due to the microprocessor control system and the optimization system on the UP-700, you can get the maximum possible number of radial sawn boards.



saw cut texture: 1 - tangential cut; 2- radial cut; 3 - semi-radial cut.

tangential a cut is called, in which the cut plane passes at a distance from the core, tangentially to the annual layer of the trunk. Such boards have a pronounced texture and a rich wavy pattern of annual rings. Tangential sawn boards have higher shrinkage and swelling ratios, but are more affordable.

Sawing hardwood

The sawing operation includes decisions about board thickness, log flipping, and log taper compensation. It depends on many factors: the type of wood, the quality of the log, its dimensions, the design of the machine and the grade of lumber to be obtained. There are 3 standard cutting patterns:

Simple sawing

The log is sawn until its core is exposed, and then turned over 180° and finished sawn to the end. This is the fastest and easy method sawing, yet with this method, each piece of lumber must be cut on the sides. The lumber sawn in this way is somewhat wider and heavier, of lower quality and has a lot of waste. It is extremely susceptible to warping during drying. Therefore, simple sawing or sawing through is justified only in the case of logs of very poor quality, when all the above disadvantages are no longer particularly important.

circular sawing

When sawing in a circle, a cut is first made, and the log is turned over to a new edge, sawn, and turned over again, until at least 5 turns have occurred. From a financial point of view, this the best way for logs of medium and high quality, although at the same time, at some sawmills, it is difficult to carry out such a turn of the log, and the daily productivity will be low. Of course, a machine with hydraulics solves this problem.

Sawing timber

Cant Sawing Maximizes Productivity sawing machine(number of boards per day) and, as a rule, is used in industry when working with logs of medium and big size. In this case, the log is first sawn as in a circular saw, but the central part of the log, which may have dimensions of 18x23 or 25x25 and so on, is either transferred to another machine for processing according to production line, or sold as a large and heavy timber. Basically, medium and low quality logs are sawn in this way, when it is impossible to get valuable lumber from the central part of the log. Thus, time and effort are saved in the production of a product of not very high quality and therefore not very high price.

Deciding on which side of the log to start sawing, which cut surface to open first, is the most important part of sawing. We divide the log into 4 faces, each of which extends along the entire length of the log and occupies a certain part of its circumference. The choice of the first face is determined by the position of all others.

When sawing in a circle and sawing a bar, two basic rules apply:

The worst side of the log is sawn first, regardless of the taper of the log. Accounting for log run means raising or tilting the log so that the saw cuts parallel to the bark. Since this is the worst part of the log, it means that it will make short boards and a lot of slabs. Since we do not take into account the taper of the log, this gives us the opportunity with the opposite, better side logs to cut parallel to the bark, without lifting or tilting the log. This means that more boards of high quality will come out of this best part of the log, moreover, the same length as the length of the log.

sawing first best face wood, taking into account the taper of the log. This means that the log must be raised or tilted so that the first cut is made parallel to the bark.

The end result of both methods will be about the same, but the second method has one advantage. In this case, it is easier for the sawmiller to rotate the log, because the open edge is the cleanest, there are no defects on it. In the case of the first rule, the best part of the tree is the part opposite the open face. It is not visible, and it is impossible to accurately rotate the log. Usually, if the wood is of good quality, then both rules work almost the same. But if you encounter a worse log, it is better to use the second rule.

Sawing soft wood

Many methods used in sawing hardwood, suitable for soft varieties. But there are also some differences. Of course, safety considerations must take precedence over the desire to produce as much product as possible.

Position the log so that when sawing, minor defects in the material are inside the lumber, of course, if these defects are not so serious as to affect strength final product. If possible, cut so that all branches and defects are located on one side of the lumber, while the other side remains clean. True, in the case of building materials, a clean surface does not affect the final price of the product. But large branches or defects can affect the strength of the structure.

Pick the worst side of the log and start sawing from there, producing short lumber. The first lumber will be the worst lumber and therefore must be short in order to sell.

After the log has been sawn from the bad edge along the entire length of the log, it is necessary to move to the opposite edge, and cut parallel to the bark. With a good edge, the width of the sawn board should be at least 15 cm. On smaller logs less than 30 cm in diameter, the first board should be 10 cm wide. Huge logs will have fewer internal defects and therefore do not need to be converted to large building structures.

You should always turn the log from one side to another if the lumber from the new side is of better quality than the one that was just sawn.

Logs from waste. It is necessary to cut the "ears" in one pass of the saw, then turn the log over to the "belly", perhaps at least a few short boards can be made from it.

The main products of the sawmill industry are sawn timber. Minor - sawdust and wood chips, which are used for the manufacture of particle boards, fuel pallets, etc.

Types of materials produced at the sawmill

If you follow the “letter” of GOST 18288-77, the materials that are produced at the sawmill include:

1) Lumber

lumber- wood blanks with two plane-parallel layers and certain dimensions fixed in the regulations.

bars- lumber, the width and thickness of which is more than 10 cm, is widely used in the construction of houses, as load-bearing structures, for internal and exterior finish, manufacture of stairs, windows, etc.
bars- sawn timber, in which the width does not exceed twice the thickness. According to the geometric parameters, square and rectangular bars are distinguished. Depending on the length, these lumber is used as floor joists, bases for wall cladding, in the construction of gazebos, bathhouses and other small architectural forms, in furniture production.
Boards- lumber in which the width exceeds the double thickness dimension. Depending on the presence of bark on the side edges, they are divided into edged and unedged. Edged boards more in demand for the manufacture of furniture, windows, doors, for various finishing works- in a word, where not only the strength qualities of wood are important, but also aesthetic parameters. Unedged material costs an order of magnitude cheaper, so it is bought either for self-processing in edged board to reduce the cost of production, or is used in construction as an auxiliary material (for roof lathing, for the manufacture of flooring, etc.).
Sleepers- bars fixed size and molds that are made to support railroad tracks;

2) Blanks

Blanks- edged lumber with wane and edges, which are sawn off perpendicular to the layers in whole or in part. These include plates (half cuts of logs) and quarters;

3) Obapol

Lagging- material with an internal sawn and an outer non-sawn (or only partially sawn) layer. Plank obapol - with a half or more sawn convex part, used for the production of a picket fence and in the construction of formwork, scaffolding, strengthening mine workings;

4) Slab

croaker- the extreme parts of the log remaining during sawing. The croaker differs from both sexes in that certain ratios of thickness, width and minimum length requirements are not established for it. Most often used as an environmentally friendly fuel or for the production of wood chips.

lumber elements

Plast- wide longitudinal surfaces of the sawn log and any side of the lumber square section. The internal layers are those closest to the core of the log, the external ones are the surfaces that are farthest from the core.

edges- narrow surfaces, the processing method of which determines the separation of sawn timber into edged, partially edged and unedged;

Edge- the intersection of adjacent two sides at the lumber;

ends– surfaces perpendicular to the edges.

Classification of lumber by sawing method

Depending on the location of the layers to the annual layers, lumber is divided into:

1) Made by radial sawing

A radial cut is a cut in which the cut passes through the core of the log, at right angles to the rings. At the same time, the surface of the layers turns out to be uniform in texture and color, and the distances between the annual rings are minimal.

Boards made by the radial sawing method have excellent quality indicators (swelling coefficient 0.2%, shrinkage - 0.19%). Therefore, radial sawn timber is in demand for the manufacture of parquet, timber, lining, block-house - finished products have practically no gaps, in comparison with similar products of tangential sawing.

Saw-timber made by the method of radial sawing is the most durable and expensive. They are used in construction, in the production of massive shields and window beams. The output of a radial board is usually small (30% is already good indicator), and depends on the method that will be chosen for cutting the log. Optimal scheme sawing to obtain radial and semi-radial boards consider the following.

2) Made by tangential sawing

When sawing a log tangentially, the saw passes tangentially to the annual layers of the trunk, without affecting the core of the tree. Such lumber has a wave-like pattern, which clearly shows the patterns of annual rings and a beautiful woody structure.

At tangential boards the coefficient of shrinkage and swelling is at least twice that of the radial material, so their cost is more affordable, and the quality of the products is lower. For basic building elements such boards are not used - wood can be deformed and the product will “lead”. But, nevertheless, due to the high aesthetic qualities and low price, the demand for tangential wood high - it is used for decorative finishes furniture, doors, building elements.

Sawing lumber- the fundamental process in wood processing. First, we need to recall a few terms that are used in the woodworking industry and which are defined by GOST 18288-87 sawmill production terms and definitions:

Lumber. Materials that have one or more even sides. Depending on the ratio of length to width and the number of parallel sides, timber, bars, boards, obapol and sleepers are distinguished.

bars- thickness less than 100 mm, width does not exceed twice the thickness. This category also includes slats, only their linear dimensions are much smaller.
bar- thickness more than 100 mm, width does not exceed double the thickness.
Boards- the width exceeds two thicknesses, can be trimmed (all four sides are trimmed) or untrimmed ( sides are not cut off).
Sleepers- this is a bar with strictly defined dimensions, used during construction railways, is now rarely used.
Lagging- the more familiar name "croaker", the outer side of the whip, has only one flat surface. Most often used for further processing into wood chips.

sawing wood methods

This is very important factor, the overall yield of lumber and their quality largely depend on the method chosen. Depending on the direction of the cut to the annual rings, there are two ways:

Radial. Most quality lumber, have an excellent structure and high rates of physical strength. The saw moves perpendicular to the annual rings.
Tangential. It gives a much higher yield of lumber, but their quality is somewhat lower. The saw moves parallel to the annual rings or in a tangential direction.

The choice of a particular sawing method depends on the end use of the lumber and the condition of the whip. On the Internet you can find "strange articles" about sawing in a circle and so on. In fact, the vast majority of the whips during sawing is in one position, as a result, part of the lumber has a tangential cut (about 2/3 of the total), and the rest of the lumber has a radial cut. The top and bottom of the log are cut tangentially, only the middle is sawn radially.

At the request of the customer or taking into account own production the whip can be sawn from the sides, then turned over 90 °, sawing is performed again. As a result, a part of the unedged boards with a tangential cut is obtained, and the rest of the boards will be edged with a radial cut. Once again, we repeat that the cutting methods are selected in each case separately, taking into account the above factors. Currently, there are three types of sawmills, each with its own advantages and disadvantages. Let's talk about them in more detail.

Frame sawmills

These are the first mechanisms that began to be used for mechanical sawing of wood. Today, in our opinion, undeservedly "out of fashion." Consider objectively their advantages and disadvantages.

To make it clearer, you need to learn about the principles of work. At the frame sawmill vertical position several saws are fixed (from ten or more, it all depends on the size of the frame), the distance between the saws is set once, sawing is carried out by the vertical movement of all saws with the simultaneous feeding of the whip.

pros.

You can fully mechanize the whole process
The sawmill is easy to set up and maintain
Performance is at an acceptable level
Saws the entire whip in one pass
All received unedged boards can be cut at the same time and also in one pass
Edged board is of high quality
Time saving

Minuses

It is believed that these sawmills are converted into sawdust a large number of wood. But this is true only for older models. Previously, saws were made from not very high quality steels, the thickness of each saw was up to 3 mm, plus a set of teeth, the cut increased to 5 mm. Today, by reducing the thickness of the saw and the angle of the teeth, the thickness of the cut is significantly reduced. We will compare the thickness of the cut with a band sawmill below, you will find out what their manufacturers are silent about.

Band sawmills

They are considered the most advanced equipment, the most productive, the amount of sawdust is minimal. We will discuss this later, but first we will briefly describe their structure and principle of operation. The cut is made by closed high-speed saws, the thickness of the saws is small, the width of the cut is reduced. Sawing occurs due to the forward / return movement of one saw along the whip. To be honest, we do not notice any special advantages (for the buyer), but there are disadvantages. In order not to be unfounded, we will talk about the intricacies of the cutting process.

Sawmills require a very attentive attitude. Incorrect sharpening of teeth, incorrect tension or choice of cutting speed (all of these parameters are chosen taking into account the type of wood) cause the lumber to get a wavy surface. The height of the waves can reach several centimeters. And such a waviness of even one board negates all the “advantages of a thin cut”. The wave on lumber is a visible defect in processing and reduces the grade of lumber. The classification of wood defects is described in detail in the article of the same name.

These sawmills have a rather low productivity, requiring a lot of physical labor. For example, if your whip has a diameter of 100 cm, then calculate how many back and forth passes you need to make to cut it into boards 2 cm thick, and frame sawmill cut it in one pass. In addition, each sawn board must be manually removed from the sawmill and stored in a separate place. In this case, after each cut, you have to set the level of the saw again. Highly high degree hazards during operation. The risks of injury while working on such a sawmill increase with geometric progression- this is a break in the saw at high speeds, and the presence of metal objects in the body of the tree (and this does not happen so rarely). Problems with cleaning sawdust. They are scattered along the entire length of the sawmill, it is long and difficult to remove them.

Of course, manufacturers of band sawmills are “shamefully” silent about such “subtleties”. We advise when choosing a sawmill to take into account maximum amount factors: the required volume of lumber, the availability of qualified personnel, the features of lumber and the requirements for their quality. After all, professional workers band sawmill produce lumber of the 1st grade in accordance with GOST.

pros.

Relatively inexpensive
Sawing in both horizontal and vertical direction
Large whip thickness, up to 400 mm
Low waste
Purity saw

Minuses

Poor performance
Increased degree of danger
Complex setup
Highly qualified staff
Mandatory "rest time" from 8 to 10 hours
Cleaning

Circular sawmills

Circular saws differ from band and frame (multi-saw) sawmills in the quality of the edges and the parallelism of the face. lumber produced in circular sawmill is rightfully considered the best, but only from the point of view of the consumer. The main factor that makes lumber produced at the sawmill unavailable for consumption is the high price. High price does not allow to compete in the market building materials, despite the excellent quality of boards and beams produced by this method. This circumstance is connected with three facts affecting the increase in the cost of lumber from a sawmill:

Summarize: when choosing edged lumber, it is necessary to take into account not only the method of sawing lumber, but also the qualifications of the personnel servicing this equipment. You can buy good quality lumber from a trusted supplier, having familiarized yourself with the products according to the proposed photos on the manufacturer's website or by arriving at the warehouse finished products. The Elka-Palka company is ready to offer its services in accordance with the price lists indicated on our website. We sell only high-quality products of our own production or purchased from trusted suppliers. Mandatory quality control.

The range of lumber offered is quite wide, woodworking products differ in quality, cost, as well as in the types of wood sawing. Let's take a closer look at what types of wood cutting exist, and for this, first we will consider in in general terms what is the technology of sawing wood directly.

Sawing wood

First of all, the log is unraveled on a band or disc sawmill, turning into a gun carriage. If all sides are propylene, then the output will be edged material, which is divided into timber, small timber and edged board. Planed patronage is called lining, floorboard, platbands and plinths. Glued products include, for example, furniture boards.

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 cutting board

Radial cut- this is a saw 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 layers (two main planes of the board). The wood of radial sawn boards is quite uniform in color and texture. Such boards practically do not deform during shrinkage and do not swell from moisture, because. the change in the size of the wood occurs mainly along the line of the rings (across the fibers), and for the boards of the radial cut, they are located in thickness. Radial sawn lumber has the highest performance compared to sawn timber of other types of cut.

Tangential sawing- this is a cut that is made tangentially to the lines of the annual rings of the trunk at some distance from its core. The faces of such boards have a pronounced texture and a bright wavy pattern of annual rings. For tangential sawn boards, the coefficients of shrinkage and swelling from moisture are twice as high as for radial sawn boards, which causes their significant deformations when the moisture state changes. For this reason, tangential sawn boards are less preferred for wet conditions than radial sawn boards.

Rustic (semi-radial) and mixed cuts- these are cuts with signs of two main types of cut 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 lines at the edges (in width) of the board to arcuate ones in the middle.

Central cut- this is a cut made right in the center of the trunk and including its core. Given that the core of the trunk consists of the least durable wood, central sawn lumber has the most heterogeneous structure in terms of strength of all the types considered.

Features of the main types of sawing

At tangential sawing the cut plane passes 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 bizarre "arches", "curls", "rings". The texture of the resulting tangential sawn board is not uniform, wood pores may be present. On some of the dry boards, delamination may form on the surface after fine planing. After tangential sawing, the boards are characterized by higher shrinkage and swelling coefficients, moreover, such a log sawing scheme allows to increase the useful yield coefficient, which in turn leads to a reduction in the cost of the board.
For radial cutting of wood, the cutting plane is perpendicular to the annual rings. With this method, the texture of the board is quite uniform with a minimum distance between the annual layers. It not only creates beautiful drawing, but also contributes to increasing the strength of lumber.

Boards radial cut They are distinguished by good resistance to external influences, they have greater resistance to deformation and wear resistance than tangential sawn boards.

The shrinkage and swelling coefficients of radial sawn lumber are 0.18% and 0.2%, respectively, which is almost twice as good as that of tangential sawn lumber. The reason for this phenomenon is that for radial sawn boards, shrinkage and swelling occur along the thickness of the material, in contrast to tangential sawn boards, in which dimensional changes occur along the width of the board. This explains the fact that finished products (parquet board, floor board, block house, imitation of timber, lining) from radial sawn lumber on the front surface almost do not have cracks, which is not excluded from products from tangential sawn lumber. To obtain glued beams by splicing wood without knots, blanks and boards of precisely radial and semi-radial cut are used, since the mechanical and geometric characteristics of the beam depend on the resistance of the fibers, which increases when gluing layers with multidirectional annual rings with an angle of inclination up to 45 °.

The average efficiency of radial sawn boards is only 10-15%. This explains their high cost. Radial sawing includes lamellas, in which the angle between the annual rings and the face is 60-90°. If the specified angle is in the range of 45-60°, such boards are referred to as semi-radial sawing. the best operational qualities has lumber, in which the angle between the annual layers and the cutting plane is 80-90 degrees. Taking into account boards of a semi-radial cut, the coefficient of useful output can reach 30%.

Usually, during radial sawing, the log is initially sawn into quarters, and then from each quarter boards are sawn alternately from two layers. For sawing logs in a radial way, for example, rip saws UP-700 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 a radial sawn board based on the optimization criteria for the maximum yield of finished products, as well as the conditions of radial and semi-radial cut.

Comparing the radial and tangential types of cuts, we can draw several conclusions:

Radial lumber has the best properties shrinkage and swelling.
Radial cut boards have better mechanical characteristics and dimensional stability.
The wood of the radially sawn boards has a uniform shade and uniform texture, which gives a special decorative value. finished goods from wood.
Due to its characteristics, radial boards find more wide application, although they are more expensive.

The main dimensions of lumber

There are standard dimensions for 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 according to the highest purity class.

The edged board can be 2.5 cm, 4 cm or 5 cm thick, 10 cm wide, 15 cm wide, and be standard 6 m long. The length of a small beam, in addition to the typical value of 6 m, can also be equal to 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 layer, and on the opposite side - untreated wood.

Lumber Selection Criteria

Before choosing good lumber, the first step is to find out the type of wood offered. It can vary from 4 to 0 depending on the number of knots and their quality. Be sure to check the length of the lumber and the dimensions of the section. If bends or rotational deformations are visible, then it is better to refrain from buying such products. You can check the evenness of the lumber by attaching a stretched cord.

Interested in the rules of industrial sawing of wood, as well as the differences and characteristics of wood different way sawing. So if you're interested, read on. Knowledge will be useful when buying building materials and building a country house.

There is a radial cut, in which the cut plane passes through the core of the trunk. The wood of such boards is quite uniform in color and texture, the inter-ring dimensions are minimal. Boards of radial cut-2 are resistant to external influences, practically do not undergo deformation and have high wear resistance. The radial sawn board has a shrinkage ratio = 0.19% and a swelling ratio = 0.2%. These figures for radial sawn lumber are twice as good as for tangential sawn boards. For a radial sawn board, the process of shrinkage and swelling goes along the width of the fibers - the thickness of the board, and for a tangential cut, along the width of the board, because. the fibers at the "tangent" are arranged in width. Accordingly, a floorboard, a parquet board, an imitation of a beam, a block house, a wall paneling - a radial cut - has practically no gaps compared to similar products of a tangential cut. design features:

Since the output of radial sawn boards is 10 - 15% of the total volume, their cost is quite high. Scheme of sawing for the maximum obtaining of a board of radial-2 and semi-radial cut-3.

A cut is called tangential-1, in which the cut plane passes at a distance from the core, tangentially to the annual layer of the trunk. Such boards have a pronounced texture and a rich wavy pattern of annual rings. Boards of tangential cut - 1 have higher coefficients of shrinkage and swelling, but are more affordable.

Radial cut-2 wood - a method of sawing a log, in which all the fibers in the board go along the direction of the annual rings. When sawing radially, lumber has the best physical and mechanical properties. The strength and hardness of wood with a radial cut is higher than with a tangential cut.

The output of the board of the radial cut-2 is usually small (does not exceed 30%). On the UP-700 rip saws, the output of the radial sawn board reaches 60%. Such a high rate is achieved thanks to the cutting optimization system. Choosing among the optimization criteria the maximum exit of the board of the radial cut, the conditions of radiality and semi-radiality-3 of the cut, the technologist determines the percentage of the exit of the radial board.