Serebrennikov Yuri Plywood is a laminated material consisting of glued together sheets of veneer sheets of various types of wood, is also possible to combine layers of veneer with other materials (such as: rubber, metal, etc.). Rotary cut veneer wood to receive special (shelling) machine tools that cut him in a spiral about the longitudinal axis of rotation of roundwood (Churakov - logs). Basically peeled veneer manufacture sheets in length and width of 1300 mm to 3000 mm. The thickness of the veneer can vary depending on the type of plywood in the range from 0.35 mm to 4 mm. Plywood is classified by a number of grounds: Operational Grade plywood veneer appointment of Mark plywood format sheet thickness of plywood emission class design sheet Surface Maintenance Breed assignment of wood veneer, depending on the operational use plywood is subdivided into groups: Plywood General Purpose Construction plywood furniture veneer plywood decorative plywood Bakelized Aviation Plywood Boards Plywood Laminated Veneer plywood for general purposes. This wood laminate consisting of glued together three or more sheets of veneer sheets with mutually perpendicular arrangement of wood fibers in the adjacent layers. Plywood adhesives can be applied veneer of hardwood and softwood, and it is assumed that the sheet of plywood is made of the wood making up its outer layers. For general purpose plywood does not have special requirements. Properties of the plywood with GOST 3916.1-96 "Plywood utility with outer layers of hardwood veneer and GOST 3916.2-96" Plywood general-purpose outer layers of veneer from softwood veneer. Depending on the used glue plywood is divided into two brands: "PSF" - plywood increased water resistance, glued phenol formaldehyde glues and "FC" - plywood, waterproof (water-resistant plywood), glued urea formaldehyde glues. Regardless of the wood used for the manufacture of plywood, it is divided into grades according to the varieties of exterior (front and back) of the layers of veneer. With the designation grade plywood indicate first grade face layer, and then working. Possible grade plywood from hardwood: E / E, I / I, II / II, III / III, IV / IV, E / I, I / II, II / III, III / IV, E / II, I / III, II / IV, E / III, I / IV. To indicate the kind of plywood veneer softwood to the designation of varieties of veneer is added to the letter s, for example, EX / IX. According to the degree of mechanical surface treatments are divided into plywood sanded (NS), polished on one side (SH1), and both sides (R2). Humidity plywood should be 5-10%. The format of plywood is subdivided into the following types: 1525H1525 mm (60 inches) - the so-called Russian plywood, because this veneer is traditionally made in the USSR and manufactured in Russia until now. In accordance with GOST one of the dimensions of such a veneer can be reduced to the size of 1270 mm (50 inches). One of the leading manufacturers of plywood in Europe is Finland, which manufactures plywood format 2440H1220 mm. Therefore, it is often called a veneer of Finnish, although the manufacture of such plywood was launched at the Perm plywood mill with 70 years of 20 century. Piece of plywood in this format is called "large-format". In addition, Russia has made plywood with the following formats: 1830H1525 mm and 3050 mm X 1525 mm, plywood with such formats also applies to big-size plywood. In the group of big-size plywood sometimes isolated groups: longitudinal plywood - it's a veneer, in which the grain of wood exterior veneers coincides with the long side of a sheet of plywood, plywood shear - when the fiber direction coincides with the short side of a sheet of plywood (this division is important, t . since it affects some physical and mechanical properties of a sheet of plywood, especially in thin plywood). A characteristic feature of the construction of plywood - a large thickness. The furniture is of high quality plywood surface. In the manufacture of decorative veneer applied synthetic resin. Bakelite plywood is made from sheets of birch veneer. Construction plywood. This term is used when involve the use of plywood for construction work as a structural material (floors, walls, ceilings, walls, etc.), as well as shuttering in-house. In this regard, to such high demands on plywood surface quality (grade), and even more to sand the surface of the plywood does not show. The main varieties of construction plywood - it's Grade III and IV. A plywood glue adhesives based on phenol-formaldehyde glues. In addition, construction plywood - plywood is large thickness, for example, for the shuttering plywood is recommended thickness of 18 and 21 mm. Most often used for the construction of softwood plywood or a combination, made of veneer thickness of more than two millimeters, which leads to a reduction in the cost of plywood, but the physical and mechanical properties of such plywood is not actually changed. Also to include construction plywood laminated plywood that is used only for the reusable formwork in concrete construction. Furniture plywood. In contrast, construction plywood, furniture plywood to the very high requirements: the quality of the surface of plywood, dimensional stability and quality of the bonding sheet. The quality of the surface of plywood include indicators such as defects and quality of grinding. Furniture plywood can be used as decorative. If necessary, highlight the texture or imitations of other species of wood, are used dyeing and then polish. Decorative plywood. It is a material glued together from sheets of veneer and coated with film coatings based on synthetic resins, in combination with decorative paper or not, during hot pressing. Decorative plywood is subdivided into: - Total veneered sides - by the unilateral and bilateral - in appearance - a glossy and semi-matt - by type of coatings and resins used for the manufacture of the following brands: DB-1, DF-2 DF -3, DF-4. Decorative plywood is mainly used in construction, shipbuilding, and furniture industries. Bakelite plywood. This plywood is made from sheets of birch veneer, glued phenol, preferably alcohol-soluble, resin. Bakelite plywood manufactured at a relatively high pressure using a large amount of glue, so it has high strength and dimensional stability. The density of plywood bakelized 1200 kg/m3 (ie, a plywood sink in water). Bakelite plywood manufacture length 1500-7700 mm, width 1200-1550 mm. Quite often you can hear that this is called marine plywood or bakelite, which is synonymous bakelized plywood. Birch plywood aircraft. This title received a birch plywood because it was used in aircraft, where the main requirement for the materials was a high strength at low density. Aircraft plywood is composed of three or more odd layers relatively thin veneer of high quality birch veneer. The thickness of the aviation plywood should be minimal (the minimum thickness of three-layer aircraft plywood - 1 mm, the bonding layers of veneer are using a bakelite or phenolic film adhesives). This plywood is used in the manufacture of light aircraft, in the manufacture of musical instruments and other areas that require guaranteed structural properties. Plywood is manufactured in length from 1000 to 1525 mm, width from 800 to 1525 with the graduation of 25 mm and the maximum deviation ± 4 mm. Plate the plywood. Plywood boards are made of seven or more layers of veneer glued together with synthetic adhesives based on phenol-formaldehyde and urea-formaldehyde resins. Plywood boards are used in agricultural, manufacturing sporting and other special designs, which require a good bend in one direction, a sheet of plywood panels. Brands, sizes and technical requirements for plywood are given in GOST 8673 "plywood boards. Specifications ". Laminated plywood. Laminated plywood surface creates a high resistance to various environmental effects. This property makes laminated veneer indispensable in the manufacture of wear-resistant surface (mold manufacture reusable concrete formwork, etc.). The advantages of laminated plywood: exceptional durability, quick installation and easy handling, water resistance and corrosion resistance, resistance to detergents, combined with other materials, options and imprinted smooth surface and a choice of colors and transparency of the surface. Exterior plywood different varieties GRADE I. No more than three wood defects or defects in processing, such as: - lack of veneer, defects of the sheet edges of plywood when sanding and cutting no more than 2 mm - pin-healthy, accrete, light and dark knots, with a diameter of 15 mm, partially fused , loose knots, holes, worm hole diameter not exceeding 6 mm, the number of 3 pieces per 1 m2 - Crook - cracks not exceeding 200 mm in length. SECTION II. No more than six wood defects or defects in processing, such as: - Health, accrete, light and dark knots, a maximum diameter of 25 mm - partially fused, unjoint, loose knots, holes, worm hole diameter not exceeding 6 mm in quantity 6 pieces per 1 m2 - crack length not exceeding 200 mm - overlapping veneer in the outer layers of a length not exceeding 100 mm; - shortage of veneer on the edges of a length not exceeding 4 mm, - the presence of adhesive tape, glue seepage, no more than 2% , scratches, dents, vyrovy fibers, not more than 5% - inserts from the timber. SECTION III. No more than nine wood defects or defects in processing, such as: - Pin knots, sound knots, without limitation diameter, partially fused, unjoint, falling, knots, holes, worm hole diameter not exceeding 6 mm, consisting of 10 pieces of 1 m2 - Diverged cracks not exceeding 300 mm and sealed up to 600 mm - overlapping veneer in the outer layers of not more than 200 mm; - shortage of veneer, defects of the sheet edges not exceeding 200 mm - oozing adhesive is not more than 5% - Tension fiber not more than 15% - a gap in the compounds permitted width of no more than 2 mm - insert a timber without any restrictions. SECTION IV. Allowed any number of flaws and defects, without limitation, such as: - partially fused, unjoint, loose knots, holes, worm hole diameter to 40 mm. Brands plywood: FC and PSF on the degree of water resistance adhesive bonding plywood is subdivided into grades: - Plywood WBP - plywood increased water resistance, adhesive glues based on phenol-formaldehyde resin - plywood FK - water resistant plywood (also known as - water resistant plywood), glued together with glue on based on urea-formaldehyde resin. Format plywood Plywood is regular size and large-format. In the manufacture of plywood, basically mastered the following sizes of plywood sheet, mm: Common format for large-format 1525h1525 1830h1525 1525h1475 2440h1220 1525h1350 2500h1250 1525h1270 3050h1525 1525h1220 3000h1500 1475h1475 1270h1270 1220h1220 thickness of the plywood sheet thickness of plywood production plant, mostly ranging from 3 to 30 mm . Also allowed to manufacture plywood other thicknesses in accordance with the terms of a specific agreement or contract. Construction sheet of plywood for construction of a plywood sheet and plywood production can be a mutually perpendicular and parallel arrangement of wood fibers in the adjacent layers of veneer, symmetrical and asymmetrical, veneer of the same breed and different breeds. Surface treatment of plywood on the degree of mechanical surface treatments plywood is subdivided into: not polished - NS; polished on one side - R1, Sanded two sides - R2. Kind of wood plywood is made from one wood species from which made its outer layers. For plywood used veneer hardwood (birch, alder, maple, elm, beech, aspen, poplar, linden, etc.), as well as veneer softwood (pine, spruce, fir, larch and cedar, etc. n). Plywood made from wood the same or different species, divided respectively by a homogeneous and kombinirovannuyu.Tolschina veneer applied to the outer layers of plywood, must not exceed 3.5 mm and inner layers - 4.
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