Blockboard is made of natural peeling veneer and solid wood panel glued, hot pressed plate. From the structural point of view, it is formed by gluing veneers on both sides of the core, and the core is a solid wood plate (or grid frame) formed by splicing core strips (ie, wood strips). The core strips can be glued together. Can also be no plastic pendulum, according to which can be classified as rubber blockboard and non-glue blockboard. The two sides of the core board can be respectively laminated with one or two layers of veneers. According to this, they can be classified into three layers of blockboard and five layers of blockboard. For example, the structure of five layers of blockboard is panel, core board, board core, core Board and backplane.
Different processes, different quality
The production of a large core board requires more than 30 processes. After the logs are processed into boards, they must first be dried, and then restored under natural conditions. The final moisture content is controlled at about 7%; the reduced boards are sliced, spliced, and glued. , pressure and other processes produced.
The core board processing technology of the big core board is divided into two kinds: machine fight and hand fight. Hand-made spelling is to put wood strips by hand, and the wood strips are subject to less lateral extrusion force, larger gaps between the wood strips, uneven splice gaps, and poor nail holding power. The mechanically-punched core planks are subjected to a large squeezing force, the gap is extremely small, the splicing is smooth, and the bearing weight is uniform. Therefore, the compact structure of the machine splicing sheet is not easy to deform due to its long-term use.
Different materials, different quality
Daxin board can be divided into "excellent product", "first class product" and "qualified product" according to the quality of the material and the texture of the surface material. Some companies also classify plate grades as Grade A, Grade A, and Grade A. However, this is only a corporate behavior. There is no “Level 3A†in the national standard. This kind of labeling is currently not allowed on the market.
There are many kinds of material in the core of the core board, such as poplar, birch, pine, paulownia, etc. Among them, poplar and birch are the best, and the texture is dense, the wood is not soft and hard, and the nail holding power is strong and not easily deformed. The paulownia texture is relatively soft, absorbing large moisture, not easy to dry, made of plate in the use of the process, when the water evaporates, the plate is easy to dry deformation. The hard wood is hard, difficult to suppress, the splicing structure is not good, the nail holding force is poor, and the deformation coefficient is large.
The surface material can be laminated on one side or two layers of veneer on both sides of the core. According to this, it can be classified into three layers of blockboards and five layers of blockboards. The surface materials are divided into willow, eucalyptus and teak by tree species. Wait. The surface of the good quality Daxinban surface material is smooth and flat, and it is not easy to warp and deform. According to the sanding condition of the surface material, the panel can be divided into one surface light and two surface light types.
Quality intuitive judgment
The national standard stipulates a number of quality standards for large core boards, including thickness dimension, web size, warpage, physical and mechanical properties, material defects, processing defects, moisture content, bonding strength, board surface defects, and formaldehyde emission limits. Most of these rigorous inspections of quality indicators need to be performed in the laboratory, but consumers can judge their quality with simple and intuitive methods.
Appearance: Appearance should be flat and flawless, logo must be complete. The quality blockboard panel should be smooth and free of defects, such as no dead knots, digging, leaking, etc., the thickness of the middle plate is uniform, there is no overlap, from the seam phenomenon, the core board is closely spliced, especially the blockboard can not be at both ends There is chapped phenomenon. When erected, the corners should be straight and the diagonal error should not exceed 6 mm. The whole package of blockboards should fit completely between each board.
Touch: Touch the surface of the Blockboard by hand. The high-quality blockboard should be dry and smooth.
Since the internal quality of the Daxin board cannot be understood from the appearance, consumers can also judge it by a simple method. The big core board observes the bright light, such as the whiteness, indicating that the wood strips are not spliced ​​together tightly; when they are picked up, they hear the sound, and there is a buzzing sound indicating that the glue strength is not good; lift up one end of the blockboard, and squeak, the high-quality joiner The board should have a sense of integrity and heavyness. Of course, such a heavy feeling should be a good thing if the hand feels dry. Otherwise, it is not dry enough. Then, tap the surface of the plate with a sharp-nosed device to hear if there is a big difference in the sound. If there is a change in the sound, there is a hollow inside the plate. These phenomena will reduce the overall bearing capacity of the plate. Uneven stress will cause the plate structure to be distorted and deformed, affecting the appearance and the effect of use.
Can not ignore environmental performance
Because large core boards are generally used in the splicing of the core board and the splicing of the panels, urea-aldehyde glue is generally used, and what we now call formaldehyde is actually emitted from the glue. Therefore, the main difference between environmentally friendly large core boards and poor quality large core boards lies in the quality of the glue. If the core board is made of eco-friendly glue, only the dry wood smell will be produced at the production site, and the pungent smell of formaldehyde will not be heard. If the blockboard emits a pungent odor, it means that the formaldehyde emission is high and it is best not to purchase it.
Several consumer misunderstandings
"The trimming and smooth sheet must be good." This argument is wrong, in fact, the more the board consumers, the more careful. Edge trimming is produced when the machine is sawing. A good sheet usually does not require “reprocessingâ€, and often there are many hairy children. However, due to the fact that the interior of the sheet with quality problems is hollow and ruddy, the processor will “consciously dress up†it, put a “good-looking†wood on the edge, and polish it to make it confusing to consumers. It must not be used as a standard to measure who is better or who is bad.
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