Inspection of particleboard quality
The types of wood moisture content, wood dry and wet mainly depend on its moisture content, usually expressed in terms of moisture content. The percentage of the weight of water in wood and the weight of wood itself is called the moisture content of wood. Wood moisture content is divided into absolute moisture content and relative moisture content. The absolute moisture content is calculated based on the weight of dry wood, and the relative moisture content is calculated based on the weight of wet wood. The quality of particleboard can be determined by water content, swelling rate of water absorption thickness and density.
Particleboard moisture detector
1. Measuring the moisture content of each specimen of Particleboard
(1) The weighing specimen should be weighed immediately before drying, and the accuracy is 0.01g. If it is not possible, preventive measures should be taken to avoid the change of moisture content from sawing to weighing.
(2) The specimen is dried in a drying chamber and dried to a constant mass at 103 soil temperature of 2 C. Constant mass means that the difference of moisture content between two volumes at intervals of 6 hours is less than 0.1%.
(3) After drying to a constant mass, the weighing specimen is cooled to room temperature in the dryer and weighed quickly to prevent the moisture content from exceeding 0.1%. The weighing accuracy is 0.01go(4). The absolute moisture content of the specimen is calculated by calculating the moisture content of the specimen with an accuracy of 0.1%.
(5) Calculate the moisture content of the board. The moisture content of one or several particleboard is calculated separately, which is equal to the arithmetic average value of the moisture content of all specimens. The value is accurate to 0.1%.
2. Measurement of Particleboard Density Determine the Density of each Particle of MDF and Particleboard, respectively
(1) The weight of each specimen is weighed to 0.01g by lowering the mass of the specimen to a constant value in standard climate.
(2) The length and width of the specimen are measured by vernier calipers. The measuring points of the MDF specimen are shown in Fig. 1-28, and the length and width are the arithmetic average values measured in two places, which are accurate to 0.1 mm. Particleboard specimens were measured in the middle of the specimens with an accuracy of 0.1 mm. The thickness of the specimen is measured by micrometer, and the thickness of four circles is measured by four-point thickness measurement method (Fig. 1-28). The accuracy is up to 0.01 mm. The arithmetic average of the four-point thickness is the thickness of the specimen, which is accurate to 0.01 mm. When using micrometer, the measuring surface of micrometer should be placed on the specimen slowly, and the applied pressure is 0.02 MPa.
(3) Calculate the volume of the specimen according to the measured size of the length, width and thickness of the specimen, and calculate the volume of each specimen, accurate to 0. lcm3.
(4) Calculate the density of each specimen according to the weight of the specimen and the volume of the calculated specimen. Use the density formula to calculate the density of each specimen, accurate to 0.01g/cm3.
(5) Calculate the density of the board to calculate the density of the MDF and particleboard specimens, respectively. The density of the two plates is equal to the arithmetic average of the density of all the relevant specimens in the same plate, which is accurate to 0.01g/cm3.
(6) According to the density deviation formulas of MDF and particleboard, the density deviation of each board can be calculated accurately to 0.1%.
3. Measurement of swelling rate of water absorption thickness: determination of swelling rate of water absorption thickness for each specimen of Particleboard
(1) In the initial thickness measurement, the specimen is lowered to a constant mass in standard climate, and the thickness is measured by micrometer at the center of the specimen to O.Olmm (MDF to 0.05 mm).
(2) The specimen is immersed on the shelf and immersed in water of 20 (+2 (+25 (+2 (%) medium density, so that the water surface is 20 mm higher than the specimen. All the specimens should be in the same water layer, neither floating on the water surface nor sinking under the water. There should be a certain gap between the specimens, allowing them to expand freely.
(3) Measuring the final thickness of particleboard samples by soaking for 2 hours or 24 hours (soaking for 2 hours in the drying state for general board, furniture and interior decoration board, soaking for 24 hours in the drying or wet state for structural board and reinforced structure board), soaking for 24 hours for medium density fiberboard samples, taking out the samples, wiping off the surface water, and immediately in the original measurement. The thickness is measured with the same accuracy as the initial thickness. The measurement must be completed within 30 minutes.如无特殊说明，文章均为本站原创，转载请注明出处。If there are no special instructions, the articles are original, if you want to use or reproduce, please indicate the original source www.plywoodinspection.com,If you find that our articles infringe on your copyrights and interests, please email us at firstname.lastname@example.org in time and we will delete it at the first time.