Edged board is one of the most common lumber in construction. It is used for outdoor work, during construction wooden houses, interior decoration, manufacturing wooden fences. The board is sawn from logs and additionally sawed along the edges. This gives the lumber not only a marketable appearance, but also protects it from various pests. Typically the width edged boards twice its thickness.
The greatest demand in construction is for boards made from coniferous species wood - spruce and pine, Siberian larch. For the production of furniture, more expensive and durable types of wood are used - oak, alder, ash.
The quality and cost of lumber depends on many characteristics: the type of wood, its moisture content, processing and sawing technology. Therefore, it is important to correctly calculate the output edged lumber in production.
depends on many factors: the specification, the grade of the board, the diameter of the saw log.
For example, from round timber In coniferous species, the yield of edged lumber on band sawmills is usually 55 - 60%. On disk sawmills this percentage increases to 70-75%.
Output of edged boards from round timber hardwood(aspen, birch, linden) is always very low for all types of sawmills. Approximately 35-40%. This is due to the curvature of hardwood logs. You can increase the percentage output only by setting optional equipment- multi-rip, edge-edging and slab machines. The yield, in this case, will increase by about 20%.
Generally? prices for lumber fluctuate greatly, and many lumber companies provide edged boards at a price significantly lower than the market price. However, before you buy lumber from such sellers, you need to think about what pitfalls may be hidden here. Often the cost of boards is reduced due to the low quality of lumber. Thus, it is most appropriate to purchase edged boards from those companies for which selling wood is not a new thing.

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Sawn timber yield rates from roundwood

In the report of the UN European Commission/FAO Timber Committee ECE/TIM/DP/49 on timber conversion factors different types forest products, in particular, the yield coefficients of sawn timber from round timber are given. These data, based on the experience of 16 countries, may well serve as guidelines for woodworking enterprises as world standards.

Lumber covers a significant portion of solid wood lumber products. They include a wide range of products from unedged, fresh sawn to edged, dry, sized and planed lumber. The type of products produced has an impact significant influence on the yield of final sawn products from round timber. So from one cubic meter round wood you can get 0.8 m3 unedged lumber and only 0.4 m3 of dry edged, sorted and planed lumber. That's why various countries was asked to provide their yield ratios for various categories of lumber products to understand why national lumber yield ratios differ so widely from each other.

For example, in Germany, 1.67 m3 of roundwood is required to produce 1 m3 of softwood lumber, while in the USA it is 2.04 m3. At first glance, it may seem that sawmilling in the United States is less efficient compared to Germany (the given coefficient indicates that the production of the same volume of lumber in the United States requires 22% more roundwood). But when taking a closer look at the production of the same types of lumber, such as rough lumber and dry lumber, it turns out that lumber yield rates in these countries are similar. This means that the differences in lumber yield ratios lie in the output various types finished products. Obviously, Germany produces more rough-cut lumber, while the USA produces more dry and planed lumber.

Some countries note that lumber production in their countries is recorded in the fresh sawn form to avoid double measurement of volumes for dry and planed lumber. This is in contrast to other countries, especially the Scandinavian region and North America, where the volume of lumber is most often given taking into account its final processing. This, for example, could result in a rough green lumber yield ratio of 1.57 (64%) or 1.75 (57%) for dry lumber or 2.27 (44%) for planed and finished lumber, as shown in the diagram below.

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To obtain a high percentage of lumber from round logs, several different technologies, including certain cycles of actions. The time required for sawing round timber and the labor intensity of the process varies, depending on the chosen processing method, the location of the work, and the season. Thus, some enterprises build workshops for the primary processing of raw materials near the timber harvesting site and save on this.

Not only trunks, but also large branches are processed. Roundwood logs are sorted by size and presence of bark. The trunks that have not been sorted are used later for rough work (manufacturing scaffolding and etc.). When accepting raw materials from the supplier, not only the cubic capacity is checked, but also the presence of damage, rot, knots - such materials do not comply technical specifications. Defects in wood reduce the percentage of finished products at the output, and knots can damage equipment.

Before sawing, trunks are often debarked (bark is removed using a special machine) - this process is optional, but is considered economical:

• due to the absence of stuck pebbles and sand in the bark, the saw is protected from premature wear;
• the quality of the chip material improves;
• some enterprises do not accept slabs from unbarked logs for processing;
• the error in results when sorting wood using electronics is reduced.

Types of wood cutting

First of all, you need to decide on the type of cut - there are several of them. Tangential - the cut goes tangentially to the growth rings, the surface is obtained with patterns in the form of rings and arches. Boards obtained in this way are cheaper, but have high percentages of shrinkage and swelling.

Radial - a cut along the radius, perpendicular to the growth rings, the pattern is uniform, the yield of the board is small, but it is of higher quality and greater strength.

Rustic – carried out at any angle, defects, knots, sapwood, etc. are visible.

Cutting methods

For each specific case, a cutting method is selected.

Tumbling is the most economical, almost no waste, high percentage of finished timber. The output is unedged boards and two slabs.

With lumber - first you get a double-edged beam, unedged boards, and two slabs. Then the timber is sawn perpendicular to the cut into edged boards, along the edges two unedged boards and two slabs are obtained.

Sector - first, the log is sawn into 4–8 sectors, and then each of them into radial or tangential materials. Sometimes several are cut out in the center unedged boards.

Break-up-segment - with this type of cutting, two or more unedged boards are cut in the center of the trunk, and edged one-sided boards are sawed from segments on the sides.

Beam-segment - similar to split-segment, only in the middle of the log a two-edged beam is cut, which is then sawn into edged boards. The yield of lumber is high.

Circular - after sawing off one or more unedged boards, the log is rotated 90 0 and the following boards are sawed off. This method is used when a large log is affected by heart rot in the center. With its help, healthy wood is separated from low-quality wood.

Aggregate – using milling tools And circular saws simultaneously with high-quality lumber, technological chips are obtained at the output (instead of slabs and slats). Such complex forest processing allows for rational use of raw materials and labor costs. This results in waste-free production of finished lumber.

Necessary tool

The choice of tools depends on the quantity of planned finished products, their quality and product sizes. Most often, cutting is performed circular saw. At certain stages of production, the use of special machines is required.

The circular saw makes precise cuts in any direction, copes well with any size of log, and is suitable for professional and home use.

It is used for home use when it is necessary to prepare a small amount of lumber. It's easier to do more difficult jobs with a chainsaw than to buy expensive equipment. All you need for it is a special attachment, a barrel fastener and cutting guides.

Machines for removing bark. They are quite expensive, but with regular use in the enterprise where they are performed large volumes work, quickly pay for itself. They are not required to be used, but are desirable because they can provide a number of economic advantages and conveniences in the production process.

You will also need:

• Disc machine – for obtaining unedged output materials from the forest.
• The band sawmill produces high-quality lumber and a low percentage of waste.
• Frame sawmill does not require a foundation and can be installed directly in logging sites.
• Universal machines are capable of producing high-quality material even from low-grade wood.

In enterprises with mass production to obtain ultra-precise and quality products entire complexes are installed modern equipment, and sawing of wood is carried out of any complexity.

Sawing technological map

To calculate the optimal percentage of obtaining finished lumber from logs, a forest sawing map is drawn up. You can do these calculations yourself or use a special computer program. Such information can also be obtained in a regular reference book, which contains information on sawmilling operations.

The cutting map allows you to determine how much will be at the output finished products, what percentage of waste will be recycled. From these data, it is possible to determine final cost products. The result may largely depend on the type of forest. There are some measures to increase the percentage of lumber yield.

The percentage of lumber at the output is ready-to-use, useful wood. Waste is the raw material for producing MDF, chipboard, and fiberboard. These volumes will depend on the diameter of the tree, the types of solid wood products being manufactured, and the sawing option.

Percentage of round timber

Accurate calculation of each cubic meter of wood - an expensive natural raw material - is important in every woodworking enterprise. Cubic meters of roundwood are calculated in several ways.

By volume of transport. Each type of transport has its own forest cubic capacity calculated and determined. For example, a carriage holds 70.5 cubic meters of round wood. Then there will be 22.5 cubic meters of it in three cars. This method of calculation speeds up the acceptance of raw materials, this is especially important when large quantities received cargo. But there is a large error in the calculation results in this way.

Calculation based on the volume of one trunk. If the entire logging consists of timber of the same size, then by counting the volume of one, you can count them all and multiply by the cubic capacity of one. This method is more accurate, but requires a lot of time and the involvement of more workers to accept the cargo.

Automated systems with measuring frames. These measurements provide higher percentages of accuracy than those taken by humans. When logs pass through the measuring frame, all thickening and curvature of the trunk and even knots are taken into account. In this case, you can immediately sort the trunks.

A method of calculation by multiplying the volume by a coefficient. The height, width, and length of the stack are measured and multiplied by a coefficient. This calculation is fast, but with a low percentage of accuracy. It is used when it is necessary to urgently determine the number of cubic meters.

Dependence of the final yield percentage on sawing technology

To increase the yield of finished lumber, it is necessary to optimize the sawing process itself. This is especially true when working with workpieces that have curvature, damage or other flaws:

• First, you need to select and put into production only high-quality wood.
• Then select trunks with damage at the ends (rot, cracks) and trim these places.
• If there is a section of trunk with a rotten core, it must be removed and the remaining wood cut into lumber. They will be shorter, but of better quality.
• The circular cutting method is also suitable for obtaining high-quality boards.
• The yield percentage is higher when sawing timber with a larger diameter.

The yield also depends on the quality of the log, the type of wood, and the equipment used. New high-quality, well-tuned equipment allows you to process trunks with almost no losses.

The efficiency of forest cutting can be increased if taken in advance special measures. To do this, you need to make accurate calculations using digital programs. If you do this manually, the percentage of output defects will be higher. It should be taken into account in advance that coniferous forest species produce a higher percentage of lumber output. Because their trunks are smooth, large, less susceptible to rotting and therefore almost free of defects. A large volume of deciduous trees is often discarded.

For rational use For wood, it is better to take short logs. But in domestic production Typically, trunks with a length of 4 m or more are taken for sawing. Due to their curvature, the output results in a large percentage of rejects.

Unedged boards……………………………………………. 13 Business slab………………………………………………….. 16 Sawdust and cuttings………………………………………………………………. 13 Shrinkage………………………………………………………………. 8 When carrying out practical calculations, these figures should be clarified based on a study of local conditions. Wood debarking waste. The amount of bark found on wood depends mainly on the species, as well as on the age of the trees, their growing conditions, trunk diameter, etc. The total amount of bark obtained by debarking wood at enterprises, taking into account the loss of bark during the logging process, varies ranging from 10 to 14.5% of the volume of marketable wood. When transporting wood by raft, part of the bark falls off and the actual yield of bark is on average 8...

Current norms for lumber yield when sawing

For example, with rot in the core, then the log is sorted and sawed into lumber, instead of being turned into timber.

Or vice versa, if the sapwood is rotten, but a beam emerges from the central part, and the log is a timber log, we sort it for sawing into timber.

You need to think similarly in terms of blueness and curvature.
Approximate yield by variety The situation by variety is quite interesting.

Attention

It turns out the percentage of output premium grades depends on the following factors:

• The coefficient of production of lumber from round timber.

Grade depends not directly, but indirectly.

Guidelines for determining the volume of secondary wood resources

Table 1 - yield of boards when sawing round timber Diameter, cm Yield of the highest grades, % 12 - 16 yield of the first grade 40% 18 - 22 on average 50% 24 - 26 about 50% 28 - 40 timber timber, in the production of timber you can get indicators about 70% 42 - 60 about 60 - 70% How does the percentage of lumber production depend on sawing technology? In addition to diameter, grade, defects (curvature) and length, the percentage of board output depends on the technology of sawing wood and the type of equipment.

Stages of sawing round timber

Info

He only cuts graded wood;

• Circular saw equipment cuts according to individual cuttings - this is a big plus for the resulting materials, both in quality and quantity.
Video on the topic And now I’ll answer why high yield is not always good, but everything is simple at very high rates, the amount of boards with wane increases.

Important

The result is low-grade lumber and its total cost from a log at a certain point becomes lower than the cost of high-quality materials.

Yes, and the implementation is not quality material may be more difficult.

Amount of wood waste

During the sawmilling process, various pieces of waste are obtained, which in some cases are used for energy purposes.

Lump sawmill waste is formed from the peripheral part of the logs and, in the absence of preliminary debarking of the logs, contains such an amount of bark that they can be used for pulping and production. wood boards impossible.

Volumes of formation of various types wood waste as a percentage of the volume of sawn raw materials are given in table. 14. Name of logging waste Including 13. Amount of waste generated during logging production Amount of waste per 1000 m1 of annual warehouse turnover, m3 Amount of waste from exported wood, % At the cutting site A.
Solid or lumpy from Hody: Branches, twigs, tops 14.00 140 65 75 Roots 11.00 110 .
110 - Stumps 3.00 30 30 - Points 1.75 17 - 17 Canopies 0.75 7 - 7 B.

Sawing round wood: cutting map, necessary tools

In what sequence should the round timber be cut? Please note! Coniferous wood species are considered the best option, due to the fact that they have a straight trunk and a relatively larger diameter.

In addition, such wood is not as susceptible to decay, which leads to less waste. When working with hardwood, 2 processing methods are used:

1. Using band sawmill at 375 or 363.
2. In ruins.

   This technology involves cutting out a half-beam, which is subsequently passed through a multi-saw device.

In this case, the first method allows you to get approximately 40-50% of the output.

But the collapse technique differs in a slightly larger volume - up to 70%.
The disadvantage of this technology is that its costs are relatively high.

Methods of cutting wood Sector - first the log is sawn into 4–8 sectors, and then each of them into radial or tangential materials.

Sometimes several unedged boards are cut in the center. Break-up-segment - with this type of cutting, two or more unedged boards are cut in the center of the trunk, and edged one-sided boards are sawed from segments on the sides. Beam-segment - similar to split-segment, only in the middle of the log a two-edged beam is cut, which is then sawn into edged boards. The yield of lumber is high. Circular - after sawing off one or more unedged boards, the log is rotated 900 and the next boards are sawed off. This method is used when a large log is affected by heart rot in the center. With its help, healthy wood is separated from low-quality wood.

How much waste is generated when sawing wood?

It's easier to do more difficult jobs with a chainsaw than to buy expensive equipment.

All you need for it is a special attachment, a barrel fastener and cutting guides.

Machines for removing bark. They are quite expensive, but with regular use in an enterprise where large volumes of work are performed, they quickly pay for themselves.

They are not required to be used, but are desirable because they can provide a number of economic advantages and conveniences in the production process.

The fact is that after some golden mean, the more planks we get per cubic meter, the higher the amount of low-grade wood with wane;

• The larger the diameter, the higher the likelihood of getting more high-quality boards;
• The presence of wood defects, such as curvature, rot, blueness and others; the fewer there are, the higher the percentage of obtaining a high-quality board;
• The shorter the finished product, the higher the percentage of high-quality boards.

Now let’s estimate, approximately based on the diameter, the percentage of first-class lumber obtained from the total volume of boards produced.

To do this, I made everything in the form of a small table.
Hello dear readers and subscribers of the blog, Andrey Noak is in touch with you! Today I will tell you about the yield of lumber when sawing round wood.

• 1. Introduction
• 2 Percent from round timber
• 3 Why does the useful percentage depend on the diameter of the wood being cut?
• 4 Ways to increase your ratio
• 5 Approximate yield by variety
• 6 How does the percentage of lumber production depend on sawing technology?
• 7 Videos on the topic

Introduction This parameter is one of the most important indicators in sawmilling.

The efficiency of sawing wood depends on this indicator.

Many beginners mistakenly believe that the higher this ratio, the better.

In fact, this is not always the case; most specialists know about this, but remain silent. I repeat once again - a high percentage of lumber yield per cubic meter of forest is not always good.

Repair and construction work often involves the use of lumber. But shops and timber trading centers often sell them not in pieces, but in cubes.

The number of edged boards in 1 cubic meter.

Everything is very simple and fast.

Method for calculating edged lumber

• a caliper, tape measure or folding m; if the length parameters of wood products are known, you can limit yourself to a regular ruler;
• calculator - suitable mobile phone, smartphone, if problems may arise with mental arithmetic;
• a piece of paper and a pencil - to record the results of calculations, how many boards are in a cube.

1. Volume = Length × Height (product thickness) × Width.

To prevent confusion when converting cubic centimeters to cubic meters, it is more convenient to immediately record the measurement results in meters.

Calculation of the weight of a cubic meter of wood.

For example, 0.132 cu. m = 6 m × 0.022 m (2.2 cm) × 0.10 m (10 cm).

Now, to determine the number of planks in a cube, you need 1 cubic meter. m divided by 0.132. The result obtained (7, 5757) when purchasing timber must be rounded to 8 pieces.

This method of calculating cubic capacity is also suitable for timber. This way you can determine how many cubic meters of timber you need to purchase if you know the required number of products, or, conversely, determine required quantity cubes

To determine the required volume of timber, the easiest way is to carry out calculations similar to the above method. Only the final result needs to be multiplied by 1.2 - a correction factor. From unedged boards you can get no more than 70-80% of edged ones.

The width and thickness of each product are measured taking into account its further processing. The technique will help determine the number of cubes wooden products, necessary for work, if the final result is planned for their further processing - pruning.

When purchasing, the widest and thinnest boards are measured to obtain an average width. If the width of the lumber at the butt is wider than at the top, the arithmetic mean of their dimensions is used without taking into account the bast layer or bark, rounded to 10 mm. In this case, fractions from 5 mm are rounded to the full 10 mm, and fractions up to 5 mm are not taken into account. The length and thickness of the lumber are measured in the usual way. The volume of timber is determined according to the usual scheme:

Scheme for calculating the cubic capacity of a log.

• the volume of one product is calculated;
• the total cubic capacity of purchased timber is determined; according to GOST it is used correction factors: 0.96 – for lumber from softwood, 0.95 – for lumber from deciduous wood.

In addition to the piecemeal method for determining the volume of unedged lumber, the geometric method can be used.

Requirements for a package of unedged timber:

• lumber is laid tightly, without overlaps, in horizontal rows;
• on one side the ends of the boards are aligned;
• all sides of the package are strictly vertical: according to GOST, the displacement of individual products outward and inward should not exceed 0.10 m;
• The package of lumber must be the same width along its entire length.

Then the volume of the package is calculated, the resulting result is multiplied by the coefficient:

• 0.67 – the number of ends in the unaligned side of the package is more than 50% of total number boards;
• 0.50 – if there are only 50% ends;
• 0.33 – the number of ends is less than 50% of the total amount of timber.

Piece or geometric methods for determining cubic capacity will help you navigate when purchasing unedged timber. If you have problems with payments, you can seek help from a sales consultant, manager, or warehouse employee.

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