In the national standards, there are many quality standards for large core panels, including thickness, width, warping, physical and mechanical properties, material defects, processing defects, moisture content, bonding strength, panel defects, formaldehyde emission and so on.
The strict inspection of these quality indicators mostly needs to be carried out in the laboratory, but consumers can judge their quality through some simple and intuitive methods.
Appearance: the appearance should be smooth and defect-free, and the logo should be complete. High-quality blockboard should be smooth and free from defects, such as knots, repairs, glue leakage, etc. , and the middle plate should be uniform in thickness, without overlapping and splitting, and the core plate should be closely spliced, especially the joinery board should not have cracks at both ends. Placed vertically, the corners should be straight, and the diagonal error should not exceed 6 mm The whole package of joinery boards should fit each other completely.
Touch: Touch the surface of the joinery board by hand. High-quality joinery board should feel dry, smooth and smooth.
Internal quality: with good appearance quality, we should pay more attention to internal quality. Otherwise, the big core board that looks flat and clean outside will not be like this after sawing-black dead wood, rotten wood or many big gaps.
Internal quality should first check whether the filler is dense, whether there are obvious cracks and rotten wood strips, and there may be eggs in the rotten wood strips, which are easy to be eaten by insects in the future; Look at the phenomenon that there is no glue and putty around. This phenomenon is generally to make up for internal cracks or holes. Because the internal quality of the core board cannot be known from the appearance, consumers can also judge it by a simple method-observing the core board under the light, if it is transparent, it means that the wood strips are not tightly spliced; Pick it up and listen to the sound, there is a "creaking" sound, indicating that the bonding strength is not good; Lift one end of the joinery board and weigh it. High-quality blockboard should have a sense of integrity and weight. Of course, this kind of heavy feeling should be good when it is dry, otherwise it is not dry enough. Then tap the surface of the flat plate with a pointed tool,
Listen to whether there is a big difference in sound. If the sound changes, it means there is a hole in the board. These phenomena will weaken the overall bearing capacity of the plate, and the long-term uneven stress will distort the plate structure and affect the appearance and use effect. 2. Wire comparison:
1) Look. See if there is a quality system certificate; See if the certificate is standardized; See if there is a factory name, address, inspection stamp and production date; See if there are any trademarks, specifications, voltages, etc. Printed on the wire.
It also depends on the cross section of the copper core of the wire. Superior copper is bright and soft, otherwise it is inferior. 2) try. It is recommended to bend the end of the wire repeatedly by hand. All products with soft hand feel, good fatigue strength, elasticity in plastic or rubber, and no crack on conductor insulator are excellent products.
3) Weighing. High quality welding wire is usually within the specified weight range. For example, the common plastic insulated single-stranded copper conductor with a cross-sectional area of 1.5mm2, per 100 m weight1.8 ~1.9kg; 2.5 mm2 plastic insulated single-stranded copper core wire, with a weight of 3 ~ 3 100 m1kg; The weight of 4.0 mm2 plastic insulated single copper core wire is 4.4 ~ 4.6kg per kloc-0/00mm, and the wires with poor quality are not enough in weight, length or copper core impurities.
4) Look at copper. Qualified copper core wire copper core should be purple, shiny and soft to the touch. The cop core of that false copper core wire is purple black, yellow or white,
Many impurities, poor mechanical strength, poor toughness, a little hard will break, often broken wires. When checking, just peel off one end of the wire by 2 cm, and then gently rub it on the copper core with a piece of white paper. If there is a black substance on the white paper, it means that there are many impurities in the copper core. In addition, the insulation of fake and inferior wires seems to be very thick. In fact, most of them are made of recycled plastics. Over time, the insulation layer will age and leak electricity. 5) Look at the price. Because of the low production cost of fake and shoddy wires, vendors often sell them at low prices under the guise of good quality and low price, which makes people fall for it.
3, sand contrast:
High-quality cement particles are fine; Inferior products have rough feel, low strength and poor viscosity when used. If there is no sand in cement mortar, the solidification strength is almost zero, and the quality of sand directly affects the performance of cement mortar. The industry usually divides sand into four types according to specifications: ultra-fine sand, fine sand, medium sand and coarse sand.
Generally speaking, the coarser the sand, the higher the strength of the prepared cement mortar, but too high strength will also lead to some bad results, such as cracks in the ground leveled with it, so it is recommended to use medium sand in home decoration. In the market, the finer the sand is, the cheaper it is. Be wary of unscrupulous merchants replacing coarse sand with fine sand. Consumers can judge the quality of sand by hand feeling and soil content. In addition, experts also specially remind consumers to be wary of unscrupulous merchants replacing medium sand with fine sand and replacing natural sand or river sand with sea sand. The state prohibits the use of sea sand in building decoration, because although the sea sand is clean, it has high salt content and alkalinity, which has a great impact on the quality of the project. To tell whether it is sea sand, we can see if the sand contains tiny shells of marine life. In addition, both natural sand and river sand must be screened before they can be used. Of course, there are screened sand on the market, but the price is about 1/3 higher. Consumers should choose according to their own economic affordability. 4, waterproof contrast:
Waterproof paint can look at whether the color is pure, whether there is sediment, etc. Then put the sample in a cup and soak it in clear water, and observe it for a few days to see if the water becomes turbid, whether it expands and whether there is emulsion precipitation, and then take out the sample to see if it becomes worse and softer during stretching. It is very unfavorable for this kind of material to be immersed in the environment for a long time, and the waterproof quality cannot be guaranteed.
Touch, fold, bake, tear, pull, etc. Judge the grade of materials by hand, such as SBS modified asphalt coiled material: (1) soft to the touch and elastic to rubber; (2) The asphalt coating on the section can draw longer filaments; (3) There is no crack at the crease after repeated bending; (4) There is no shrinkage and deformation during construction, and no bubbles appear; (5) During hot melt baking, the grease is uniform; This is a high-quality product. EPDM coiled material: (1) Rub the surface with white paper without precipitation; (2) A good product cannot be torn by hand, or it is curved rather than straight when torn. After curing, water drops are dripped on the surface of the rigid plugging and impervious material. If the water drops are not absorbed and spherical, they are good materials. If water droplets are absorbed, they are not good impervious materials.
Both natural sand and river sand must be screened before they can be used. Of course, there are screened sand on the market, but the price is about 1/3 higher. Consumers should choose according to their own economic affordability. 4, waterproof contrast:
Waterproof coating can see whether the color is pure or not, whether there is sediment, etc. Then put the sample in a cup and soak it in clear water, and observe it for a few days to see if the water becomes turbid, whether it expands and whether there is emulsion precipitation, and then take out the sample to see if it becomes worse and softer during stretching. It is very unfavorable for this kind of material to be immersed in the environment for a long time, and the waterproof quality cannot be guaranteed.
Touch, fold, bake, tear, pull, etc. Judge the grade of materials by hand, such as SBS modified asphalt coiled material: (1) soft to the touch and elastic to rubber; (2) The asphalt coating on the section can draw longer filaments; (3) There is no crack at the crease after repeated bending; (4) There is no shrinkage and deformation during construction, and no bubbles appear; (5) During hot melt baking, the grease is uniform; This is a high-quality product. EPDM coiled material: (1) Rub the surface with white paper without precipitation; (2) A good product cannot be torn by hand, or it is curved rather than straight when torn. After curing, water drops are dripped on the surface of the rigid plugging and impervious material. If the water drops are not absorbed and spherical, they are good materials. If water droplets are absorbed, they are not good impervious materials.