Sawlog: What Is It? From Coniferous Species And From Larch, The Percentage Of Yield And Sorting Of Wood, GOST And Technologies For Cutting Sawn Timber

2024 Author: Beatrice Philips | [email protected]. Last modified: 2023-12-16 05:33

For large logging companies, an important element is sawlog … And the method of cutting it affects the quality indicators of the resulting sawn timber.

What it is?

Sawmill production is familiar with the concept of "sawlogs" and is, one might say, one of the basic ones. Sawlog is called nothing more than logs - round timber, obtained as a result of cutting down trees of various species: coniferous or deciduous.

Timber should not only be cut down - roots, tops, branches are separated from it. Sawing materials are divided into logs and logs. Each type has its own purpose and scope.

Types and sizes

Two GOSTs apply to sawn timber . What happened as a result of cutting down conifers (pine, larch, cedar, etc.) is subject to GOST 9463-88, and what happened as a result of cutting down hardwoods (these are oak, beech, maple, birch, aspen lumber, etc.) - 9462-88. The main purpose of the sawlogs is to cut them into raw materials, which in the future will serve for various fields of applied and artistic creativity, construction and other industries. In accordance with the standards, no matter what species - deciduous or coniferous - the sawlog belongs, according to such a parameter as thickness, it is divided into 2 types: medium and large.

The thickness is not measured anywhere, but only at the tip end. Average thickness - diameter 14-24 cm, large - more than 26 cm. The length of the sawlog is also divided, more precisely, its length should not be less than a certain value, depending on the breed. For example, coniferous sawlog should have a length in the range of 4–6.5 m, soft deciduous species (this includes both birch and aspen material) - at least 3 m. In both situations, gradation is also taken into account - it should be 0.5 m For solid hardwoods, the length requirement is from 1 m, the gradation is 10 cm.

Sorting of material matters. Northern sorting of conifers should fall within the length interval of 3, 9–7, 5 m, Black Sea sorting - 4–8 m. This calculation does not include the so-called length allowances, they range from 3 to 6 cm. as a result of sawing the sawlog, measured in meters, and the thickness - in millimeters.

Another parameter for evaluating a sawlog is its grade. There are three of them

• The first grade includes logs with a regular round cut and shape that do not have curvatures in length. Such logs have few knots.
• Logs of the second grade have both curvatures and knots, but they do not have wood defects.
• There are wood defects in the logs of the third grade, they may be slightly rotten.

The highest quality is traditionally obtained from timber from a forest in the north of Russia. This is due to the conditions and the rate of its growth - slow due to cold weather. Such trees have a large number of layers in the trunk. They make the most durable and dense logs.

The logs can be sorted by purpose: the log can be resonant, aviation, ski, etc . Both sawlog and the lumber that is obtained from it must meet the size and quality of the GOST, which falls under the influence of. In order to build a house, you will need a sawlog with four different diameters: from 300 to 320 mm, from 260 to 280 mm, from 220 to 240 mm and from 180 to 200 mm.

The sawlog of the first grade (that is, the best) is good for the construction of various kinds of capital structures made of wood … It will make a solid and beautiful house, a bathhouse, a summer cottage complex. Wood is an environmentally friendly, durable and reliable material, especially if it is properly dried and treated with antiseptic compounds against decay and fungus. Also, wood, especially conifers, contains a special substance that kills bacteria that are sources of diseases and purifies the air in the room.

It is from the sawn timber that it is best to erect practical and beautiful wooden buildings.

Where is it applied?

The main purpose of sawlogs is the production of all types of sawn timber that are used in almost every area of the national economy . If we talk about ridges, then the lumber obtained as a result of their processing is divided into a bar, bars and a board. Most often, the material is cedar, fir, spruce, pine, aspen, linden, birch, oak of appropriate sizes.

Cutting technology

In each lumber, three areas can be distinguished: edge, edge, face . The degree of material processing also divides lumber into two large groups: edged and unedged. For the former, each face and each edge are cut, for the latter, only both faces are cut. Edged lumber has the same width of the inner and outer layers, this can be seen with the naked eye. As for the width of unedged lumber, it must be calculated: it is equal to half the sum of the two widths (inner and outer layers). Measure the width in the middle of the workpiece.

When considering edged lumber, it is necessary to designate such a thing as "wane ". This is the name of the defect that occurs during processing. The sag can be sharp or dull. The first is in the edge area. The presence of a sharp wane means that the use of such lumber is unacceptable. As for the blunt wane, it reduces the quality of the edged lumber, but it can be used. The difference between boards and bars and beams is in width.

The width of the board is always twice as large as its thickness. The bar has a width of no more than double thickness, and the bars have a width and thickness of more than 100 mm.

The sawlog yield percentage is calculated in several ways

• If the entire log has the same diameter of the trunks, then the percentage of output is calculated as follows: first you need to calculate how much volume one trunk has, after which the cubic capacity of the cut material is multiplied by this obtained volume. The error of this method is small.
• If the volume of cut timber is large, then it can be considered by the number of vehicles, roughly speaking, "cars". The error of the method is large, but the method significantly saves the calculation time.
• In the case where high accuracy and low calculation error are required, a measuring frame method will be required. Then it is possible to measure both the curvature and the thickening of the trunks, but with manual calculations this cannot be done. By using the measuring frames, the lumber can be sorted immediately.

Possible defects

Parameters of timber products such as diameter, width, length are not the only determinants of the volume and quality of the final product. The presence or absence of defects is equally important. The main indicator of the quality of the lumber to be processed is the yield . Any kind of lumber has a grade. Division into grades implies the presence either on the surface or inside the material of this or that defect or defects that have a negative impact on strength, wear resistance, reliability, and appearance. Any defect automatically lowers the quality of lumber, which means that it narrows the range of possibilities for its use.

The output determines which cutting technology will be chosen, which structural and technological cutting scheme is applicable in one case or another, and how its quality groups will be formed . The cutting plan is also drawn up taking into account the approximate output of lumber. If the number of defects is minimal, then the output is affected only by the parameters of the processed sawn timber and the inevitable process waste generated in the process. Then the calculation can be made according to the standards for timber products of the 1st grade. If the number of defects is such that the losses will be greater than the final product, it is difficult to calculate the yield. Wood blemish is any feature of the surface or structure of a material that deviates from the norm. This can be both the presence of growths on the surface, and infection with fungus or mold.

All types of wood defects are divided into two types: primary, that is, those that were formed during the growth and development of the plant, and secondary - these are already associated with poor-quality wood processing (sawing, improper storage, etc.).

In accordance with GOST 2140-81, 9 groups of defective wood. These include:

• the presence of knots;
• cracks;
• modified shape of the trunk;
• the presence of structural defects inside;
• defeat by a fungal infection;
• the presence of chemical staining;
• biological damage;
• the presence of processing defects, mechanical damage, foreign objects;
• the existence of warpedness.

Depending on what defects and in what quantity are present in the wood, it is divided into grades: first, second or third.