The quality of lumber. Description of lumber grades. Their characteristics. The rules and regulations.
“Metric starts” in the lumber sorting area in Russia began in the ’90s, when the market economy once again “open a window” to the economy. For some manufacturers while global market is a kind of panacea for others – “the tyrant”, trampling the traditional approach of management. And no matter how painful at the time was no transition, now is not a theory, but the practice is driven by modern leaders woodworking enterprises. In the field of view of each participant timber industry – output, with a minimum of complaints from foreign consumers and accurate sorting is considered a turning point for the subsequent rebirth into a new timber, the perfect shape.
Wood processing involves, as a rule, with a variety of operations, but none of them has received such an extensive debate in the world community as sorting. And the thing raskhozhesti regulatory documentary base of standardization at the international level, and what is acceptable in one country may well be a stumbling block in the transaction to another.
The dominant feature in the segment of international certification in the field of forest products are some documents that act as a guide for exporters of sawn timber products.
• Nordic Timber
«NORDIC TIMBER» – Scandinavian standard sorting softwood lumber. It comprises 4 groups of lumber grades: A, B, C and D and the same premium podsortov: A1, A2, A3 and A4. The terms and requirements for lumber, as set out in these rules, make an immutable basis during the transaction for the supply of lumber to the interested party.
• European standard for softwood lumber
Standard EN 1611-1: 1999 “Sawn timber – Visual sorting of softwood lumber – Part 1: European spruce, fir, pine, Douglas fir” classifier contains five grades of lumber 0, 1, 2, 3 and 4, and specifies the processes of sorting lumber, based on of the rules on knots. G2 sorting process takes into account the guidelines only knots in the wood layers of the product. A sorting process G4 includes specifications for knots and seams and edges. Moreover, the corresponding sorting processes are stipulated in the contract of the provider country and according to CEN should be according to EN 1611-1.
• Structural Timber
British Standard BS 4978: 1996 “Softwood lumber Visual strength grading” defines a set of requirements for visual sorting by varietal basis, as well as the requirements for certification of sorting staff. Regarding the sort we are talking about general constructing sort – GS and special constructing sort – SS. Noteworthy is the fact that the re-sorting are not subject to the export plan lumber past marked by this standard, and this stage of processing of the product under the auspices of the certification bodies under the auspices of the British Committee, such as TRADA (British Association for the research and development of timber, which has an official representative office in the capital) .
• Timber Joinery
The European standard EN 942: 2007 “Timber Joinery. General classification of the quality” of regulates the classification with respect to the surface of the timber apparently (after product assembly), and hidden characters. According to the standard, there are 5 kinds of joinery lumber – J2, J10, J30, J40 and J50 (numerical prefix denotes the allowable diameter of knots on the visible surface of the material). In addition, the standard display conditions repair problem areas on the material, as well as recommendations on the formation of the specification, collection of rocks, by humidity.
In the domestic workshop, sorting is based on the standardization with respect to the target destination, and supplies high-quality in two ways – visual and measurement-visual. In this case the domestic market condition softwood according to GOST 2292-88 provides for the division into five grades: 0, I, II, III, IV, and hardwoods in three classes (I, II, III). At the same time harvesting of hardwood is 3 grades (1, 2, 3); softwood blanks, rods, bars – 4 grades (1, 2, 3, 4); sleepers, blank ski – 2 grades (1, 2); preform air – 4 groups (1, 2, 2a, 3), – two grades (1, 2).
Separation of the sawn timber export on the Black Sea and is 5 prisevernoy sorting grades (1, 2, 3, 4, 5) – GOST 26002-83. And 1, 2 and 3 grades are combined into a group “bessortnye”, and 4 and 5 are recorded in a separate column documents acceptance.
Do not lie down on the division of classifiers blank resonance, for details of horse carriage wheel; lagging; bars for weaving shuttles to the heels, spools, reels; conversion boards for railways narrow and broad gauge; wooden slats for snegozaderzhivayuschih shields; parts milled wooden building; Glued conversion bridge for broad gauge road; trays, kits; riveting coopers; Details greenhouse frames; roofing materials. The denomination only indicates the percentage of clean wood workpiece, but not its general appearance.
Structural share in the domestic market, depending on the resistance to bending in accordance with GOST 21554.2-82 presented in two varieties – K19 and K24. In the Scandinavian countries, taking into account these parameters softwood sawn timber divided into 4 major grades (A, B, C, D) and 4 premium podsorta: A1, A2, A3, A4. And exporting enterprises have to increasingly be guided by foreign standards for sorting in order to improve the competitiveness of their products.
Of course, a set of regulations and rules requires prudent manager to follow the letter of the law, and take fully into account all the nuances of standardization in your company.
At the moment there is a direct sorting of assortments distribution groups. Or rather – put the emphasis on the type of wood, its qualitative characteristics, size (thickness, width and length), the extent of the cut (edged and unedged) and destination. From sorting process depends entirely on the further intended use of the material, and here it is important to distinguish between quality defects: swirls, metik, sprout; manufacturing defects: wane, risks mossiness, weirs and other; condition defects: blue, moisture, shrinkage cracks, discolored. In such an extensive list of indicators can not but pay tribute to the significant theme in the sorting process – the classification of grades of lumber.
“Wood is a natural material and by its nature may have many characteristics and defects that need to be understood and taken into account when using it. Classification of timber during processing helps to a greater extent to determine the value and potential use of each piece of wood “, – told us in” AVA-Company “.
According to experts, despite the fact that the sorting rules intended for use in the domestic US market, their knowledge must be buyers of sawn timber all over the world. The quality of purchased timber will determine the further costs and losses associated with the production of finished products. Since the variety of timber depends on the percentage of clear wood in each board, many of the other characteristics of the wood may not be taken into account in the calculation of the net generation. It is on this fact draws attention with illustrations of basic grades of lumber. Hardwood lumber are usually classified by size and the number of segments (pieces), resulting in processes that may be used in further production. classification rules were developed to determine the production of furniture of the percentage of clean, free of defects in wood lumber of every sort. Higher grades of lumber are long stretches of pure wood, while the Common grades intended for subsequent cutting into smaller pieces.
Varieties of high quality lumber, such as Select, are best suited for joinery large size, such as door frames and materials for decoration, as well as use in the manufacture of large pieces of furniture.
Varieties Common №1 and Common №2 most suitable for the manufacture of kitchen cabinets and other furniture, as well as wooden floors, including parquet. Note that re-sawn timber Common identical in quality timber harvesting high-grade varieties, but are smaller in size (both in length and width).
According to the canons
It should be understood that the sorting carelessness may cause not only an increase in waste, but also further extend article labor and material costs. Therefore, most companies revised the traditional methods of screening process and willing to “appeal” to the modern lumber sorting lines. For clarity, a simplified type of line with manual sorting plants have a capacity of up to 50,000 meters of processed timber per year, and uniform – to 120 000 m3 in the same period. The most typical part of the sorting line equipped with conveyor disassembly package and remove pads conveyors to transfer the timber, conveyor for sorting by defects scanner and meter geometry and the operating place for visual control, trim, pockets in the configuration with lifting and reset mechanisms paketoformirujushchee unit and roller conveyors discharge material. It is also used for the automation of centralized management processes at the sorting line. How does automation affect the profitability of the sorting process, and in the production as a whole?
“As a rule, modern approach to the sorting process is based on the introduction of specialized equipment in the form of programmable logic controllers (PLCs). Much of our equipment is “optimizers” that are a blend of lasers, cameras, and software. These optimizers are most commonly used for measuring wood (logs, lumber, flitches, boards, ET) and determine how to most effectively further processed timber. The combination of “optimizers and PLC” is nothing else than the logical system of establishing the most out of each log, entering the sorting, “- tells the general director of the Russian division of the company USNR Tsinger Allan (USA).
Note that the automatic operation of the equipment is the best means of obtaining significant gains in terms of overall production of processed lumber. In my opinion, due to the new solutions in the sorting set the balance between the output, production, grade and the desired range of products. There also are several scenarios fate of rejected boards: sort of job boards can be reduced, they can be cut on a special machine and divided into several smaller boards, or sent to the chipper. The chips used for the production of products such as OSB, particle board, or as fuel for heating the kilns and other things, but who wants to lose money? It is therefore advisable to modernize the sorting line and on-site to make simple equipment and assemblies, instead of sending them across the ocean.
How productive potential will have the organization and whether to follow international standards, decides to head directly himself. Only the current market dictates its own rules, and on the world stage the eternal struggle of interests of buyers and sellers holding back “dumb” servants of Themis.
To the point
Area measurement (SM)
The surface area of the board (abbreviated – SM) is measured in square feet. To determine the area of the board is necessary to multiply the width of the board in inches by the length in feet and divide by twelve, rounding the result of a number up or down. The percentage of clean wood corresponding grade is calculated depending on the size of the board, so that all boards regardless of their thickness are classified according to a single principle.
Board shown in the figure, has a width of 6 inches and a length of 8 feet. 6 1/4 “x 8 ‘÷ 12 = 4 1/4 t. E. The area of the board is 4 square feet.
Boards of this class must have a width of at least 4 inches (101.6 mm) and a length of at least 6 feet (1.8 m). Minimum production segments of pure wood is 83% on the best side. The minimum size of the segments in the boards of the class of 4 inches (101.6 mm) wide by 5 feet (1.52 m) long and 3 inches (76.2 mm) wide by 7 feet (2.14 m) length. The number of net segments depends on the area of the board and is defined by SM / 4 (see. Example of calculating the area). The other party must comply with the Common class number 1.
Sort the Common number 1
It is often called grade for cabinets, thanks to the possibility of its use in the manufacture of kitchen garnituorov. For this reason, this sort are widely used in the manufacture of other items of furniture. The minimum size of the board is 3 inches (76.2 mm) wide by 4 feet (1.2 m) in length, and the generation of pure wood segments – 66%. The minimum size of the segments of the boards of the class is 3 inches (76.2 mm) by 3 feet (0.95 m) or 4 inches (101.6 mm) by 2 feet (0.61 m). The number of net segments with a single board depends on the area of the board and are determined by the formula (SM + 1) / 3 (see. Example of calculating the area).
Sort the Common number 2
Better known as the economic grade because of its price and suitability for use in the manufacture of a wide range of furniture items. This grade is also used in the manufacture of floors. The minimum size of the boards is 3 inches (76.2 mm) wide by 4 feet (1.2 m) in length, and the generation of pure wood segments – 50%. The minimum size of the segments – 3 inches (76.2 mm) by 2 feet (0.61 m), and their number depends on the size of the board and is defined by SM / 2 (see Example area calculation.).