Wood Drying

- Aug 28, 2020-

What is wood drying?

Wood contains a certain amount of water. The amount of moisture in wood varies with tree species, tree age, and cutting season. In order to ensure the quality of wood and wood products and extend the service life, appropriate measures must be taken to reduce the moisture (moisture content) in the wood to a certain level. To reduce the moisture content of the wood, the temperature of the wood must be increased, so that the moisture in the wood evaporates and moves outwards. In the air with a certain flow speed, the moisture quickly leaves the wood to achieve the purpose of drying. In order to ensure the quality of the wood to be dried, the humidity of the drying medium (such as the currently commonly used humid air) must also be controlled to obtain the effect of drying the wood quickly and with high quality. This process is called wood drying. Because the above method uses convection heat transfer to heat the wood from the outside, it is also called convective drying.

In a nutshell, wood drying is a process in which moisture is discharged from the wood by evaporation or vaporization.

  

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What is the meaning of wood drying?

Wood has a smaller density and greater strength (higher quality coefficient), acid and alkali corrosion resistance, good insulation properties, easy to cut, beautiful texture and color and other excellent properties. In all parts of the national economy such as construction, machinery, vehicles, ships, textiles, farm tools, furniture, musical instruments, and aviation, a large amount of wood is required. However, the quality of products made of undried wood cannot be guaranteed, so the wood must be dried.

After the wood is dried, the stability of wood and wood products can be improved. Long-term exposure of wood to the air will cause swelling and shrinking. The uneven swelling and shrinking of wood will often cause cracking and deformation of the wood, affecting its use and causing waste. If you use wet wood or undried wood to make products (such as doors, windows, floors, furniture, etc.), they seem to be good when they are just finished, but after a period of time, the door frame will be skewed and the floor will be skewed as the wood dries. Phenomena such as warping, loose joints or cracks on the board surface can cause great losses. If the production unit dries the wood to the required moisture content before use, it can ensure the stability of the wood product structure, make the appearance beautiful and durable. The dried wood can ensure the quality of wood products, improve the usability of wood, extend the service life, and save wood. Practice over the years has proved that wood drying is an indispensable process in production and has become a specialized subject in science.


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Improve the strength of wood and wooden parts. When the moisture content of the wood is lower than the fiber and saturation point, the strength of the wood will increase as the moisture content of the wood decreases. The dried wood can improve the cutting processing conditions, improve the strength of wood structural parts, the bonding strength and the surface decoration quality of wood products. The thermal conductivity and electrical conductivity of wood change with its moisture content. To improve the thermal insulation and insulation of wood, it is also necessary to reduce the thermal conductivity and electrical conductivity by reducing the moisture content.

Prevent degrading and decay of wood. If wet wood is stacked in the open air for a long time, if proper measures are not taken, it will often rot or be infested by insects. When the moisture content of the wood is reduced to less than 20%, the infestation and destruction of fungi and pests can be greatly reduced. Therefore, generally in the production unit, the wood is dried to a moisture content of about 8-15%. This not only guarantees the inherent properties and strength of the wood, but also improves the corrosion resistance of the wood.