MDF, or Medium Density Fiberboard, is a manufactured wood product made from wood fibers or other plant-based fibers bonded together with adhesives like urea-formaldehyde resin. It is categorized into high-density, medium-density, and low-density boards based on its density levels. MDF is known for its smooth surface, ease of cutting, and ability to be shaped into various forms, making it a popular choice in furniture manufacturing abroad.
However, in China, the quality of MDF still lags behind international standards. While it offers good workability and durability, the national standards for high-density MDF are significantly lower than global benchmarks, which can affect its overall performance and safety. This means that not all MDF products available in the market meet the same level of quality as those found internationally.
According to the Chinese national standard GB11718-89, medium and high-density fiberboard is defined as a board made from lignocellulosic or other plant fibers, bonded with urea-formaldehyde resin or similar adhesives, with a density ranging between 0.50 g/cm³ and 0.88 g/cm³. This classification helps ensure that the material meets certain structural and functional requirements.
One drawback of high-density MDF compared to particle board is its weaker nail-holding ability. If a screw becomes loose after being tightened, it can be difficult to resecure due to the board’s relatively low internal strength. Additionally, some lower-quality MDF products on the market may contain high levels of formaldehyde, which can be harmful to human health. While airing out the boards can help reduce formaldehyde emissions over time, it's important to choose high-quality MDF to minimize risks.
When selecting MDF for furniture or construction, it's crucial to consider both the source and the manufacturing process to ensure safety, durability, and environmental friendliness. With proper handling and selection, MDF remains a versatile and cost-effective material for a wide range of applications.
The roles of the shoulder are:
(1) Prevent the ballast from scattering under the subgrade to maintain the integrity of the ballast bed;
(2) Prevent subgrade soil from squeezing to both sides under load and strengthen the stability of subgrade
(3) Provide space for setting line signs and signal signs on both sides of the line;
It is used for railway staff to walk, avoid vehicles, and store materials, machines, tools, etc. on the upper part of the line for road maintenance.
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