When sawing wood, it is important to immediately calculate what the consumption will be, as this will affect the cost of lumber. The yield of finished products may vary. It all depends on the quality of the wood used and whether measures are taken to optimize cutting. There are special measures to increase work efficiency, make the output better, and the quality of sawing higher. Before sawing, you need to pre-calculate everything. It's not as difficult as it might seem, but it costs round timber will be optimal and beneficial for obtaining excellent results.
How to increase cutting efficiency
In order for the yield of lumber to be significant, it is necessary to use special measures to increase the efficiency of the process:
- The calculation should be carried out only when using special programs; manually it will have low results, and the percentage of defects will be high.
- The round timber must first be sorted so that processing is carried out correctly.
- For cutting you need to use equipment High Quality. Otherwise, the amount of waste will be large, and the quality of the resulting lumber will be low.
- It is best to cut wide lumber first; narrow lumber takes longer to process.
- It is not recommended to take long logs.
- Before work, you should set up the equipment.
The yield of finished lumber may vary. 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 deciduous trees it can be only 10-20%.
How to optimize cutting
To increase the yield of lumber, the cutting process must be optimized. This applies primarily to those workpieces that have significant curvature. To cut a crooked round timber, you need to perform a number of steps:
- First, only suitable wood is selected for work. If the remaining logs have rot, sprouts, or cracks at the ends, then it is necessary to trim off some areas.
- If a rotten core is discovered during work, you can carefully remove it, and then saw the remaining part. This will allow you to avoid large losses and obtain boards with a length of 1 m or more with the required quality.
- 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 the round timber, sorting, and equipment. For frame shops this coefficient will be 1.48-1.6, and for lines with milling equipment– 1.6 for large forest. With a round log diameter of 12 cm or more, the coefficient can exceed 2.1.
Volume of waste after sawing
To finished board came out with a high percentage, it is necessary to prepare everything correctly, the work must be carried out only in accordance with the technology. Roundwood of coniferous and deciduous species produces different yields. In the latter case, the volume is smaller, even if you use a special optional equipment. Needles are considered more convenient for sawing, since their trunk is straight and the log has a larger diameter. Coniferous forest is not so susceptible to rotting, so there is less waste. For hardwood, 2 cutting technologies are usually used:
- with help band sawmill on Z75, Z63;
- into collapse, when a half-beam is cut out in the core of the material and passed through a multi-saw machine.
The volume of a band sawmill is 40-50%. When using technology for collapse, the yield is different, it can be increased up to 70%, but the costs of such work are higher. If you cut round timber, the length of which is 3 m, you can see that the percentage of scrap 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 could be a wormhole, which is no longer suitable for most jobs.
After sorting, the volume of hardwood material, which belongs to grade 0-2, will be only 20-30% of the amount obtained after sawing. This means that of the total mass of harvested round timber, the yield of normal boards will be only 10-20%. The remaining materials are mainly used for firewood. For coniferous round timber, the yield will be different, but attention must be paid to what average values of the resulting volume are observed.
Lumber output
In order for the yield of lumber to be optimal, numerous conditions must be taken into account. To calculate correctly, you can consider the example of round timber yield. The data was obtained from the real experience of specialists and from the performance of sawmills. This makes it possible to compare percentages and calculate optimal average numbers.
For conifers, the following solution is possible:
- For not edged 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 equal to 30%.
- For edged material, when using sawmills of 63, 65, 75, there will be a lower yield of lumber, only around 45%. For band sawmills, the yield is usually up to 55-60% finished material. If you use means to increase efficiency, you can reach 70%, although this requires great experience work.
- From a circular sawmill you can get lumber in the amount of 70-75%, although using methods to increase efficiency it may well be 80-75%. But work experience is required.
According to GOST 8486-86, for grade 0-3, the yield percentage, not taking into account sorting, is approximately 70%.
Another 30% can be left for rejecting the finished material. The rejected material is not thrown away; it is used for the manufacture of other types of lumber, which allow for the presence of certain defects.
For deciduous roundwood, a different yield percentage is observed:
- For unedged material – 60%.
- For edged wood - up to 35-40%, since the curvature of the original deciduous wood is usually large.
The output can be increased; additional equipment is used for this. This can be a special multi-sawing machine, an edge trimming machine, or a slab machine. In this case, the yield of lumber will increase by about 20%. The given percentage is given based on data on obtaining boards of grade 0-4. When sorting grades 0-1, the percentage of lumber obtained is 10%. To get a cube of finished edged hardwood material, you need to cut 10 cubes of the original round wood.
The yield of lumber from roundwood may vary. It all depends on the original type of wood used by the sawmill. Special measures to increase efficiency allow you to get a larger percentage than is possible, but for this you must have some experience.
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 preserves it from various pests. As a rule, the width of an edged board is twice its thickness.
The greatest demand in construction is for boards made from coniferous 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 coniferous roundwood, the yield of edged lumber on band sawmills is usually 55 - 60%. On circular sawmills this percentage increases to 70-75%.
The yield of edged boards from round deciduous wood (aspen, birch, linden) is always very low for all types of sawmills. Approximately 35-40%. This is due to the curvature of hardwood logs. It is possible to increase the percentage output only by installing additional equipment - multi-rip, edge trimming 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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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. This category also includes slats, only linear dimensions there are significantly fewer of them.
- 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 certain sizes, applied 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. The highest quality lumber has 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 a 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. The result is part of the unedged boards tangential cutting, and the rest of the boards will be edged with 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 are 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 resulting unedged boards can be edged 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 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 at a band sawmill produce grade 1 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.
Before sawing round timber, it is necessary to calculate how much volume will be left for further use, and how much material will be spent on processing. This is important because it affects the final cost of the product. The amount of untrimmed wood you get will depend entirely on what type of wood is used. At the same time, there are certain measures to increase the yield of lumber after cutting.
What is the yield percentage and its dependence on the diameter of lumber
To understand this, it is necessary to unpack the concept itself. Roundwood lumber yield is everything useful tree after cutting. The rest is waste that is sent for further processing to produce materials such as MDF, fiberboard, chipboard. It is worth understanding that the volume that will be obtained as a result of cutting wood is calculated for each individual diameter and selected cutting option.
It is worth understanding the question of why the parameter under consideration depends on the diameter of the forest. Everything here is extremely simple: the fewer cuts there are on the tree, the higher the volume value will be. Of course, a lot will also depend on the cutting technology and on the sequence in which the cutting was carried out. The correct sequence will be shown in Fig. 2. It should be understood that small lumber is obtained from small species of wood, and thick boards and beams are made from large timber. It is also worth considering the average diameters with approximate rates of volumetric flow rate:
- 14 – from 45 to 50%;
- 20 – about 52%;
- 25 – on average up to 57%;
- 34 – this is the diameter of timber timber, which differs in the most high value volume fraction equal to 66%;
- if the forest has a diameter of more than 40 cm, then there is a sharp decrease in the materials obtained.
Volume of waste after sawing
To finished products had a large percentage, everything should be calculated and prepared correctly. And the work process itself must be carried out in full accordance with technology. It should be taken into account that the round forest of coniferous and deciduous trees will give different yields of lumber from unedged boards in m3.
Note! Conifers wood 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 deciduous trees 2 processing methods are used:
- Using a 375 or 363 band sawmill.
- 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. When sawing round lumber 3 m long you can see enough high level marriage. In this case, the remaining wood will not be immediately useful due to the fact that it requires additional process processing.