Yield rates for lumber from roundwood

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SAWN WORK OUTPUT BASED ON FIR ROUNDWOOD VOLUME TABLES

Koptev Artem Sergeevich 1 , Weiss Andrey Andreevich 2
1 Siberian State Technological University, Bachelor in Forestry
2 Siberian State Technological University, Doctor of Agricultural Sciences, Associate Professor of the Department of Forest Inventory, Forest Inventory and Geodesy

OUT OF LUMBER BASED ON THE TABLES OF VOLUMES OF ROUNDWOOD FIR

Koptev Artem Sergeevich 1 , Weis Andrey Andreevich 2
1 Siberian state technological university, bachelor in "Forestry business"
2 Siberian state technological university, doctor of agricultural sciences, assistant professor of forest inventory, forest management and geodesy

As far back as the second half of the twentieth century, in forest inventory, it was considered expedient to determine volumes for practical purposes using special tables. Of all the tables compiled, the tables of A.A. Kründer, common to all breeds, have found the greatest use in our country, without taking into account the location of the harvested assortments on the trunks. These tables were subsequently recalculated by G.M. Tursky into the metric system, supplemented by N.P. Anuchins and approved as GOST 2708-44.

Other tables were also used in practice earlier. For example, Provatorov's table, which was compiled without any basic taxation material, purely mathematically calculated the volumes of logs, assuming one constant run for logs of all species and categories.

For Klimashevsky's tables, as well as Provatorov's tables, it was characteristic that the volumes of logs are calculated purely mathematically, assuming their division into five classes, respectively, in 1/8, 1/4, 3/8, 1/3 and 5 / 8 tops for a sazhen.

Tables of Tour, Arnold, Tursky, Rudzsky - were characterized by the compilation of the volume of logs based on numerous observations on the run and volume of logs of different species, and it was recognized that it was possible to give one general table for logs of all classes and species.

However, these tables had certain disadvantages. For example, the tables of Tur, Arnold, Tursky, Rudzkiy were not adapted to the normal taxation of logs separately and determined the volume acceptablely only with joint taxation of a larger number of logs, when smoothing out the extremes in the average result should be expected.

Also, it was not provided in the tables that the accuracy of the evaluation of logs is affected by the degree of fractionation of the thickness steps for the diameters of the logs and the total length of the logs. When taking a very large step for log diameters of 4 cm, tables for single logs or for a small number of them should give large errors due to the rounding of the diameters.

In modern forestry practice, the relationship between the characteristics of the entire forest stand and the parameters of individual trees in this forest stand is known. For example, according to studies, the density of the grown forest stand affects the quality of the timber. To improve the quality of the timber, a large stand density is needed in the early phase of rotation to reduce the growth of branches in the lower part of the trunk, their accelerated death and self-cleaning of the trunks. In the late phase of felling rotation, a relatively sparse stand is desirable for clearing branches and accelerated overgrowth of nodes. As you know, the greater the density, the less runoff, and vice versa, the lower the density, the greater the runoff, which, in turn, as it is already clear from the material presented, greatly affects the accuracy of determining the volume of assortments.

It is also necessary to take into account the impact of cuttings on the characteristics of the renewed subsequent forest stand. It is known that thinning contributed to a significant increase in the diameter of the trunk at chest level, growth in height, ratio of crown and trunk sizes, crown width, but led to a decrease in the height of the trunk to the diameter at chest height. The stem run also increased significantly, and therefore the determination of the timber stock turned out to be overestimated by 2-15%, especially for trees in thinned stands.

The international timber trade is developing very dynamically. According to the FAO, the volume of world exports of roundwood over the past decade has increased in quantitative terms by 8 million m 3 . This was facilitated by the constant growth in the global consumption of sawn timber in various sectors of the economy and the growing importance of wood as a natural, environmentally friendly universal material. The international trade in raw wood today is developing in the face of growing volumes of its consumption. The leading exporters of round timber in the world are Russia, New Zealand, the USA, and the main importers of raw timber are China, Austria, Germany. The main factor behind the growth in international trade is currently the growing consumption of wood in the world, and this trend in the world market will continue in the next few years.

Experimental studies. The studies were carried out in the Biryusinsky district forestry of the educational and experimental forestry of the SibGTU. In the lower warehouse, measurements of Siberian fir roundwood were made. In the future, the volumes of round timber were determined in various ways. We determined the output of cubic meters of lumber from a log, you can use the following table 1.

Table 1 - Determining the output of lumber

Note: With an increase in the grade of roundwood to the 1st standard for the output of sawn timber increases by 3%. When the grade of roundwood is reduced to the 3rd grade, the lumber output standard is reduced by 2%, to the 4th grade - by 7%. With a mixed supply of large and medium logs, the lumber yield standard is taken as the arithmetic average between medium and large logs.

As can be seen from the table, lumber comes out approximately 50% of the volume of the entire log. It is worth noting that coniferous lumber yield is higher than that of hardwood.

Below is a table showing how many cubic meters of lumber, wood waste and sawdust come out when using the results of the calculation using the truncated cone formula and tabular data (table 2), as well as the median section formula (table 3). The volumes are found for one log and for a hundred logs. The difference between the two lumber yields is also shown as a percentage. For 100%, the yield of lumber is taken, obtained by calculating the truncated cone formula for the first table and the middle section formula for the second.

Additionally, the cost of sawn timber obtained from 100 logs was calculated, the volume of which was determined from tabular data and the truncated cone formula (Table 3), as well as from tabular data and the middle section formula (Table 4). In addition, the difference between the cost of lumber was established.

Conclusions. Comparative analysis showed that the standard values ​​in most cases underestimate the volume of logs in terms of thickness in comparison with the truncated cone formula (-33.2-+6.4%). In the thick part of the logs, this difference stabilizes and amounts to about 10%. At the same time, in relation to the formula of the middle section, the tabular values ​​of fir logs in most cases overestimate the actual volume of round timber. In terms of value for 100 logs, the difference can be (step 36 cm) up to 60,000 rubles.

Thus, the use of the truncated cone formula makes it possible to significantly reduce the error in determining the volume of fir logs in relation to the local East Sayan mountain taiga region.

Table 2 - Yield of lumber

Continuation of table 2

Table 3 - Yield of lumber

Table 4 - The cost of lumber

1. "European Agreement concerning the International Carriage of Dangerous Goods by Road" (ADR/ADR) (Concluded in Geneva on 09/30/1957) .
2. Orlov M.M. Taxation of various assortments of commercial wood // Forest taxation. 1932. ch.14. With. 74-75.
3. Sawn timber properties of Scots pine affected by initial stand density, Thinning and pruning: A simulation based approach: Report. / IkonenVeli-Pekka, Kellomoki Seppo, Peltola Heli // Silva fenn. 2009. 43. No. 3. p. 411-431.
4. Long-term effects of precommercial thinning on the stem dimensions, form and branch characteristics of red spruce and balsam fir crop trees in Maine, USA: Report_ / Weiskittel Aaron R., Kenefic Laura S,. Seymour Robert S., Phillips Leah M. // Silva fenn. 2009. 43. No. 3. p. 397-409.
5. Varivodina I.N. , Kuznetsova E.V. , Perelygina O.G. Features of determining the volume of round timber in Russia and abroad // EUROPEAN STUDENT SCIENTIFIC JOURNAL. 2014. No. 1.

When sawing wood, it is important to immediately calculate what the consumption will be, as this will affect the cost of lumber. The output of finished products may be different. It all depends on the quality of the wood used, whether measures are taken to optimize cutting. There are special measures to increase the efficiency of work, make the output better, and the quality of sawing is higher. Before cutting, you must first calculate everything. It is not as difficult as it may seem, but the consumption of roundwood will be optimal, beneficial for obtaining an excellent result.

How to increase cutting efficiency

In order for the lumber yield to be significant, it is necessary to use special measures to increase the efficiency of the process:

1. The calculation should be carried out only when using special programs, manually it will have low efficiency, the rejection rate will turn out to be large.
2. The round timber must first be sorted so that the processing is carried out correctly.
3. For cutting, high quality equipment must be used. Otherwise, the amount of waste will be large, and the quality of the resulting lumber will become low.
4. It is best to cut wide lumber first, it takes longer to process narrow lumber.
5. Logs are not recommended to take long.
6. Before work, you must configure the equipment.

The output of finished lumber may be different. It must be remembered that at the first stage boards are obtained, then they are sorted. As a result, the percentage decreases even more, for example, for hardwoods it can be only 10-20%.

How to optimize cutting

In order to increase the output of lumber, the sawing process must be optimized. This applies primarily to those blanks that have a significant curvature. To cut a curved roundwood, you need to perform a series of actions:

1. First, only suitable wood is selected for work. If the remaining logs have rot, sprouts, cracks at the ends, then it is necessary to trim some sections.
2. If a rotten core is found during operation, then you can carefully remove it, and then cut the rest. This will avoid large losses, get boards with a length of 1 m with the required quality.
3. It is recommended to use logs with a larger diameter so that the yield percentage is higher. The coefficient can be 1.48-2.1, but it all depends on the diameter, quality of round timber, sorting, and equipment. For frame workshops, this coefficient will be 1.48-1.6, and for lines with milling equipment - 1.6 for large timber. With a round timber diameter of 12 cm or more, the coefficient may exceed 2.1.

Waste volume after sawing

In order for the finished board to come out with a large percentage, it is necessary to prepare everything correctly, work should be carried out only in accordance with the technology. The round wood of coniferous and deciduous breeds gives various output. In the latter case, the volume is smaller, even if special additional equipment is used. Needles for sawing are considered more convenient, since the trunk is straight, and the log has a larger diameter. Coniferous forest is not so prone to decay, so there is less marriage. For hardwoods, 2 cutting technologies are usually used:

• using a band sawmill at Z75, Z63;
• into collapse, when a half-beam is cut out in the core of the material, passed through a multi-blade machine.

The volume of a band sawmill is 40-50%. When using the technology in the collapse, the yield is different, it can be increased up to 70%, but the costs of such work are higher. If roundwood is sawn, the length of which is 3 m, then you can see that the percentage of rejects is quite large, and the remaining material requires processing. This applies to the bulk with boards 22x105 (110, 115) x3000 mm. There are many options for such a marriage. For example, it may be a wormhole, which is no longer suitable for most jobs.

After sorting, the volume of hardwood material that is grade 0-2 will be only 20-30% of the amount that is obtained after sawing. This means that from the total mass of harvested roundwood, the output of a normal board will be only 10-20%. The rest of the materials are mainly used for firewood. Coniferous round timber will have a different yield, but attention should be paid to what average values ​​of the obtained volume are observed.

lumber output

In order for the lumber yield to be optimal, numerous conditions must be taken into account. For a correct calculation, you can consider the example of the output of roundwood. The data was obtained on the real experience of specialists and on the performance of sawmills. This makes it possible to compare percentages and calculate optimal averages.

In conifers, the following output is possible:

1. For unedged boards and other unedged materials during sawing, the yield will be 70%. This is the amount of material obtained during processing, the amount of waste will be 30%.
2. For edged material, when using sawmills at 63, 65, 75, there will be a lower yield of lumber, in the region of 45%. In band sawmills, the output is usually up to 55-60% of the finished material. If you apply the means to improve efficiency, then you can reach 70%, although this requires a lot of experience.
3. 70-75% sawn timber can be obtained from a sawmill, although with efficiency improvement methods it may well be 80-75%. But experience is required.

According to GOST 8486-86, for grade 0-3, the percentage of yield, excluding sorting, is approximately 70%.

Another 30% can be left for rejection of the finished material. Rejected material is not thrown away, it is used for the manufacture of other types of lumber, which allow the presence of a certain marriage.

Hardwood roundwood has a different yield percentage:

1. For unedged material - 60%.
2. For edged wood - up to 35-40%, since the curvature of the original hardwood forest is usually large.

The output can be increased, for this additional equipment is used. It can be a special multi-saw machine, an edge trimming machine, a slab machine. In this case, it will turn out to increase the yield of lumber by about 20%. The given percentage is given on the basis of data on the production of grade 0-4 boards. When sorting grades 0-1, the percentage of lumber production is 10%. To get a cube of finished hardwood edged material, it is necessary to cut 10 cubes of the original roundwood for sawing.

The output of lumber from roundwood can be different. It all depends on the original wood species used by the sawmill. Special measures to increase efficiency allow you to get a higher percentage than possible, but for this you need to have some work experience.

In order for the finished board to come out with a large percentage, it is necessary to prepare everything correctly, work should be carried out only in accordance with the technology. The round wood of coniferous and deciduous breeds gives various output. In the latter case, the volume is smaller, even if special additional equipment is used. Needles for sawing are considered more convenient, since the trunk is straight, and the log has a larger diameter. Coniferous forest is not so prone to decay, so there is less marriage. For hardwoods, 2 cutting technologies are usually used:

Yield of lumber from roundwood - by grade and depending on the diameter of the logs

It's very simple, the fewer cuts to get wood, the higher the percentage. Of course, it also depends on the useful use, but once again I will say it is very important how many saws you cost to get a board. As a rule, small small boards are sawn from a small forest, and timber, a thick board are sawn from large wood.

• Use of shorter commercial timber;
• Use of specialized programs, read about it here. In short, we can say that you need to use the program to find the optimal cost of the boards obtained from the log. On the one hand, a high useful yield means a large cubic capacity, and on the other hand, a high figure means obtaining a larger volume of low-quality wood.
• The use of a thinner saw blade due to double-spindle circular saws, the use of stelite soldering.
• Use of round wood sorting by diameters, species, defects.

Actual rates of output of sawn timber during sawing

1. Boards and beams of non-standard lengths are ideally suited for the manufacture of finishing materials and furniture panels. In fact, the GOST restriction gave rise to a new direction of engineering and design thought, which was picked up all over the world due to availability. Since the middle of the 20th century, it has become widespread with an accelerated mutual exchange of technologies, due to which this type of waste has become very conditional, a number of manufacturers, even when forming price lists, allocate them in a separate column as a full-fledged material.
2. Sawdust. Chipboard material is known all over the world, from which 90% of the furniture on the planet is made. Chipboard is made from sawdust mixed with a number of resins and adhesives. With some investment, these losses became reversible, although they seemed to be the most terrible. They did the same with chips, only the processing method is completely different, because of which the material acquired other properties (it is used much less often).

Return losses include - slab, shavings, boards of the wrong length and width, sawdust, lumpy waste. To the irrevocable - the bark, which cannot be recycled and almost impossible to sell, i.e. the only use is a stove or, in some cases, pharmaceuticals (many medicines are made on the basis of the bark of many trees, and how the bark is obtained does not matter).

Edged lumber output per 1m³

The ends of lumber and draft blanks must be sawn off at a right angle to the longitudinal axis. Wane bars (with a partial absence of a cut in the edge) with a section of 120 × 120 mm or more must have a cut width at the thin end of at least one third of the side of the bar. They are made in various sizes, grades and qualities.

Sawing logs in a transverse way, lumber is obtained sharply different from each other in quality and appearance. Those taken from the middle of the trunk are called core. The wood of these boards is the most durable and stable. "Side" are called boards obtained from the extreme parts of the trunk. They are beautiful in texture and are used for finishing work. They cannot be used in load-bearing structures, because. Boards are easily deformed.

Determination of the yield percentage of lumber when sawing wood, in particular, round timber

Note! Coniferous woods are considered the best option due to the fact that they have a straight trunk and a relatively larger diameter. In addition, such a forest is not so prone to the process of decay, which leads to fewer rejects.

• 14 - from 45 to 50%;
• 20 - about 52%;
• 25 - on average up to 57%;
• 34 - such a diameter has lumber wood, which has the highest value of the volume fraction, equal to 66%;
• if the forest has a diameter of more than 40 cm, then there is a sharp decrease in the obtained materials.

Stages of sawing round wood

To obtain a high percentage of lumber from round logs at the output, several different technologies are used, including certain cycles of actions. In terms of time, sawing round wood and the labor intensity of the process varies, depending on the chosen processing method, the place of work, and the season. So, some enterprises build shops for the primary processing of raw materials near the place of logging and save on this.

Circular - after sawing off one or more unedged boards, the log turns 90 0 and the next boards are sawn 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 to optimize lumber yield from roundwood

1. The calculation should be carried out only when using special programs, manually it will have low efficiency, the rejection rate will turn out to be large.
2. The round timber must first be sorted so that the processing is carried out correctly.
3. For cutting, high quality equipment must be used. Otherwise, the amount of waste will be large, and the quality of the resulting lumber will become low.
4. It is best to cut wide lumber first, it takes longer to process narrow lumber.
5. Logs are not recommended to take long.
6. Before work, you must configure the equipment.

1. For unedged boards and other unedged materials during sawing, the yield will be 70%. This is the amount of material obtained during processing, the amount of waste will be 30%.
2. For edged material, when using sawmills at 63, 65, 75, there will be a lower yield of lumber, in the region of 45%. In band sawmills, the output is usually up to 55-60% of the finished material. If you apply the means to improve efficiency, then you can reach 70%, although this requires a lot of experience.
3. 70-75% sawn timber can be obtained from a sawmill, although with efficiency improvement methods it may well be 80-75%. But experience is required.

Sawing round wood: cutting map, necessary tool

1. Razval. Sawing wood in this way is carried out for deciduous trees with a small trunk thickness, it is considered the simplest processing. Exit: unedged elements and slabs.
2. If there is another woodworking machine, then it is possible to cut up to 65% of the material to produce edged boards of the same width. First, a two-edged timber and boards are sawn from the sides, and then a certain amount of edged lumber is obtained from the timber.
3. More specific methods are sector and segment sawing. The number of elements in the first method varies from 4 to 8, and depends on the thickness of the trunk. After separation, elements are sawn from each sector along a tangential or radial line. The second method begins with the exit of the beam from the central part, and boards are sawn from the side segments in a tangential direction.
4. For individual sawing of wood, the circular method is suitable. It is based on turning the log along the longitudinal line by 90° after each sawn board. This allows you to monitor the quality of wood and timely remove the affected areas of the trunk.

Work on the garden plot requires pruning fruit trees, and it also becomes possible to additionally produce material for outbuildings without resorting to the services of specialists, so any prudent owner would prefer to buy a chainsaw. Most often, conifers are harvested for the home, and this tool does an excellent job of sawing them. Thanks to even trunks, it is easier to outline the cut lines, which increases the speed of work. By the way, professionals most often use a chainsaw, since it is more powerful than an electric one and you can use it anywhere, regardless of whether there is a cutting or sawing of power supplies at the site.

It must also be borne in mind that saw logs are harvested in bark, which is not included in the cubature and goes to waste during sawing. Then you should take into account the length allowance, which is about 1% of the volume of the logs. The allowance allowed in the logs, as we have already said, is also not included in the cubature of the resulting lumber.

The production of lumber is inevitably associated with waste and loss of wood. The yield of lumber products depends on the degree of rationality of sawing, the sawing method, the size of the logs, their quality, the size of the lumber produced, and many other reasons. According to prof. A.H. Pesotsky, when sawing logs with a thickness of 20–22 cm into cleanly edged trimmed boards, the yield of sawn products is only 61% of the total volume of logs, waste - 33% and irretrievable losses - 6%. For certain types of products and waste, the volume of logs, taken as 100%, is distributed as follows,%:

How much waste is produced when sawing wood

The use of forest resources in our country is far from perfect. Up to 18% are logging waste. A significant part of the exported wood is firewood (up to 20%). When processing sawlogs, up to 40% of waste is generated in the form of sawdust, machine chips, and so on. After processing, only 28% of the wood becomes lumber and other products, the rest is waste.

Wood waste is called cuttings or residues from the processing of timber. For example, during logging, logging waste is formed: branches, tops, tree greens, stumps. In the sawmill industry - sawmill waste: slabs, slats, trimming boards, sawdust. Waste is obtained during the processing of lumber in plywood, pulp and paper and wood chemical industries. In general, the formation of wood waste can be displayed in the form of scheme 2.1.

Lumber is obtained by cutting logs (blanks). In essence, this is sawn timber of a certain size with two plane-parallel sides (layers). Sawing can be either radial or tangential.

On fig. 1 presents various types of lumber - from a plate to an edged board.

Figure 1. Types of lumber: a - plate; b - double beam; in - not edged board; g- quarter; d - four-edged timber with a wane; e - semi-edged board with wane; g - clean-edged timber; h - croaker; and - edged board; k - planed tongue-and-groove boards; 1- face; 2 - edge; 3 - rib; 4 - butt; 5 - wane

In lumber, the following elements are distinguished: layer, edges, ribs, ends. Plast - the longitudinal wide side of the lumber, as well as any side of the square section lumber. The best layer of lumber has the least number of defects, the best quality of processing. The layer of lumber facing the core is called the inner, and the one facing the sapwood is called the outer. Edge - the longitudinal narrow side of the lumber. Rib - the line of intersection of two adjacent sides of lumber. Butt - the end transverse side of the lumber. Wane is not an obligatory element of lumber, it is, so to speak, an element of defective edged boards due to the non-conformity of the source material (logs or blanks).

Lumber is manufactured according to GOST 8486-86E:

1) from coniferous wood - pine, spruce, larch, cedar and fir;

2) from hardwood - beech, birch, alder, linden, aspen and poplar.

The following are used: boards with a thickness of 100 mm or less with a ratio of width to thickness of 2 or less; bars with a thickness of more than 100 mm (four-edged and two-edged).

The length of lumber: softwood - no more than 6.5 m, hardwood - no more than 5 m. Lumber up to 9 m long, made by special order, can be used for special structures. The thickness and width of lumber are determined by the assortment (Tables 1, 2, 3).

Table 1. Output standard for edged lumber per 1 m 3 logs

Note:

1) With an increase in the grade of roundwood to the 1st standard for the output of sawn timber increases by 3%.

2) When the grade of roundwood is reduced to the 3rd grade, the lumber output standard is reduced by 2%, to the 4th grade - by 7%.

3) In case of a mixed supply of large and medium logs, the lumber yield rate is taken as the arithmetic average between medium and large logs.

Table 2. Thickness and width of sawn softwood in mm

Table 3. Thickness and width of sawn hardwood in mm

The ends of lumber and draft blanks must be sawn off at a right angle to the longitudinal axis. Wane bars (with a partial absence of a cut in the edge) with a section of 120 x 120 mm or more must have a cut width at the thin end of at least one third of the side of the bar.

The highest permissible moisture content of lumber for load-bearing structures is 25%, for glued structures - 15%.

The use of sawn hardwood is permitted for rafters, interior stairs, interior wall and partition cladding, ceiling sheathing, rollovers, gables, interior architectural detailing, joinery, and finished floors.

It is not allowed to use birch, linden and poplar wood for rafters; linden, alder, aspen and poplar for treads of wooden stairs; linden and poplar for clean floors.