Tangential and radial cutting. Types of sawing lumber (wood)

Wood is valuable natural material which was created by nature itself. People have been using this wonderful raw material for many centuries to build houses, create furniture, decorative items interior, and also used for industrial purposes. For these reasons, proper processing of a felled trunk is an extremely important task. Sawing and planing wood are the most important operations with wood. In this article we will talk about what wood sawing is and what types of sawing exist.

Log sawing is the process of converting valuable natural raw materials into lumber. When sawing wood various methods lumber can be obtained in various sizes. To obtain high-quality products, you need to choose high-quality, even logs that are not damaged by pests.

Types of wood cutting

The quality of the final product depends on large number factors - type of wood and quality of raw materials, professionalism of workers, proper drying. However, there is another important aspect - this is the method of cutting timber.

There are the following cutting methods:

• tangential
• radial
• rustic
• longitudinal
• transverse.

Rustic is a cut that is performed under acute angle to the direction of the fibers. This method is used in the production of lumber for rustic flooring, which can be called the most heterogeneous and original in pattern and shade.

During tangential cutting, the cutting plane lies tangentially to the annual layers of the material at a certain distance from the core. Since wood fibers are most often located in different directions, a natural pattern in the form of fancy “arches”, “curls”, “rings” is obtained on the surface. The structure of the board with this cutting option is heterogeneous; wood pores may be present. At the end of the tangential cut, the boards are characterized by an increased coefficient of shrinkage and swelling. Also, this log sawing scheme makes it possible to increase the useful yield coefficient, which causes a reduction in the cost of the final product.

Sawing wood blanks using the radial method is carried out perpendicular to the annual rings. Thus, a homogeneous board is obtained with the smallest gaps between annual layers. This creates an attractive pattern and also increases the strength of the lumber. Radial materials are characterized by high resistance to deformation and wear resistance. Also, such boards have lower rates of shrinkage and swelling compared to tangentially cut lumber. Therefore, finished products, for example, parquet board, batten, block house, lining, practically do not crack on the front part, but tangential sawing materials are susceptible to such phenomena. Glued laminated timber is created only from boards of radial and semi-radial cuts, because mechanical and geometric parameters are directly dependent on the resistance of the fibers. This resistance increases during gluing of layers with multidirectional annual rings at an inclination angle of no more than 45°.

Only 10-15% of radial boards can be obtained from a single log. Therefore they have a high cost. The most best performance demonstrates material having an angle between the growth layers and the cutting plane from 80 to 90 degrees.

Sawing wood across the grain

The technology of sawing wood across the grain is the most common method of processing timber in carpentry. At the same time, such sawing can be called the simplest. Longitudinal sawing of wood requires much more effort and certain skills.

Tools for cross-cutting timber are selected depending on the required accuracy, the amount of work and the conditions available in each individual workshop. You can use:

• electric circular saw. She makes neat and fast cuts. For household use Great suitable model with a 1000 W motor and a disk cross-section of 180 mm. Most of circular saws have a combined blade included, which can be used to implement the most various works. The teeth of this blade are something between the teeth of the transverse and longitudinal saw. For long work It is better to take a blade that is coated with carbide. Its cost is higher, but it takes 10 times longer to dull
• miter box and tenon saw. They are used for finishing. These tools can be used to make the most precise cuts.
• circular saw
• cross saw. When purchasing, please note that the teeth of such a tool should be alternately positioned to the left and to the right of the blade itself. They must be well sharpened and beveled. The most popular is a saw with 10 teeth per 25 mm blade. With 8 teeth, the saw will cut faster, but will create rough cuts.

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 the production of 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 cutting 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. On some of the dry boards after finishing planing Delaminations may form on the surface. 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 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 mechanical and geometric characteristics beams 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 radially For example, UP-700 longitudinal sawing machines can be used. The microprocessor control and optimization system UP-700 is important, 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:

1. Radial lumber has best properties shrinkage and swelling.
2. Radial cut boards have better mechanical characteristics and dimensional stability.
3. The wood of radial cut boards has a uniform shade and uniform texture, which gives special decorative value finished products made of wood.
4. Due to their characteristics, radial boards are more widely used, although they have a higher price.

Sawing lumber- a 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 terms and definitions:

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

• Bruschi- thickness less than 100 mm, width does not exceed double thickness. Slats also fall into this category, only their linear dimensions are much smaller.
• timber- thickness more than 100 mm, width does not exceed double thickness.
• Boards- the width exceeds two thicknesses, they can be trimmed (all four sides are trimmed) or unedged (the sides are not trimmed).
• Sleepers- this is a timber with strictly defined dimensions, used during construction railways, is rarely used nowadays.
• Lagging- the more common name is “croaker”, outer side the whip has only one flat surface. Most often used for further processing into wood chips.

Wood sawing methods

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

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

The choice of a specific cutting method depends on the end use of the lumber and the condition of the log. On the Internet you can find “strange articles” about circular sawing and so on. In fact, the vast majority of the logs are in one position during sawing; as a result, some of the lumber has a tangential cut (about 2/3 of the total), and the rest of the lumber has radial cut. The top and bottom of the log are sawn tangentially, only its middle is sawn radially.

According to customer's request or taking into account own production the whip can be sawed from the sides, then turned 90°, and sawing is done again. As a result, some of the boards are unedged, tangentially cut, and the rest of the boards will be edged with a radial cut. Let us repeat once again that cutting methods are selected in each specific case separately, taking into account the above factors. Currently, there are three types of sawmills, each of them has its own advantages and disadvantages. Let's talk about them in more detail.

Frame sawmills

These were the first mechanisms that began to be used for mechanical sawing of wood. Today, in our opinion, they have undeservedly gone out of fashion. Let's take an objective look at their advantages and disadvantages.

To make it clearer, you need to learn about the principles of operation. On a frame sawmill, several saws are fixed in a vertical position (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 blade.

pros.

• The entire process can be completely mechanized
• The sawmill is easy to set up and maintain
• Performance is at a very acceptable level
• Cuts the entire length of wood in one pass
• All received unedged boards can be trimmed simultaneously and also in one pass
• The edged board is of high quality
• Save time

Minuses

• It is believed that these sawmills are converted into sawdust a large number of wood But this is only true for older models. Previously, saws were made from low-quality steel, the thickness of each saw was up to 3 mm, plus the spread of the 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 the 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 cutting is done with closed high-speed saws, the thickness of the saws is small, the width of the cut is reduced. The cutting occurs due to the forward/reverse movement of one saw along the blade. To be honest, we don’t notice any particular 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 careful attitude. Incorrect sharpening of the teeth, incorrect tension or selection of cutting speed (all of these parameters are selected taking into account the type of wood) lead to the fact that the lumber gets a wavy surface. The height of the waves can reach several centimeters. And such waviness of even one board negates all the “advantages of thin cutting.” A wave on lumber is a visible processing defect 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 rather low productivity and require a lot physical labor. For example, if your log has a diameter of 100 cm, then calculate how many passes back and forth you need to make to cut it into boards 2 cm thick, and the frame sawmill will 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 saw level again. Very high degree of danger during operation. The risk of injury while working at such a sawmill increases in geometric progression- this is both the saw breaking at high speeds and the presence metal objects in the body of the tree (and this happens not so rarely). Problems with sawdust removal. They scatter along the entire length of the sawmill, removing them is long and difficult.

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

pros.

• Relatively inexpensive
• Sawing in both horizontal and vertical directions
• Large whip thickness, up to 400 mm
• Low waste percentage
• Clean saw

Minuses

• Poor performance
• Increased danger
• Complex setup
• Highly qualified personnel
• Mandatory "rest time" from 8 to 10 hours
• Cleaning

Disc sawmills

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

Summarize: When choosing edged lumber, you need to take into account not only the method of sawing the lumber, but also the qualifications of the personnel servicing this equipment. Buy lumber good quality You can contact a trusted supplier by looking at the products using the photos offered on the manufacturer’s website or by visiting the finished product warehouse. The Elka-Palka company is ready to offer its services in accordance with the price lists listed on our website. We sell only high-quality products of our own production or purchased from trusted suppliers. Mandatory quality control.

TYPES OF CUTTING LOG

• radial;
• tangential,

as well as three additional types:

• mixed;
• semi-radial (rustic);
• central.

Scheme of types of log cutting

DESCRIPTION OF TYPES OF LOG CUT

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.