The United States is located in central North America, including 48 states and Washington, DC (Alaska, Hawaii, etc. outside the home). Most of the areas belong to the temperate continental climate, the southern part has a subtropical climate, and the eastern coastal areas are characterized by temperate maritime and Mediterranean climates. The annual average wood moisture content is 12.7%, the highest monthly average is 14.2%, and the lowest monthly average is 11.3%.
The annual average moisture content of wood in China is about 13.4%, which is far above this level in many wet areas in the south. If the moisture content is not controlled during the production of furniture, the moisture content of the furniture will reach 10% to 15%. After the product is sold to dry areas, there are serious safety hazards, so it is necessary to control the moisture content of the furniture.
Generally, there are three stages of requirements for wood moisture content: (1) moisture content of the dried sawn timber, that is, the final moisture content of the sawn timber after drying, determined by use and regional considerations. Mainly used, supplemented by regions. It is generally required that the final moisture content of the sawn timber should be 2% to 3% lower than the equilibrium moisture content of the wood in the use environment (determined as 6.5% in the text).
(2) The moisture content of the wood during processing shall be determined according to the use, area and process requirements to maintain the stability of the wood moisture content, and the moisture content of the parts required for splicing and assembly shall be 2%.
(3) The wood moisture content of the finished furniture shall not exceed +1% of the annual average wood moisture content of the area of use (determined as 6%-8% in the text). The moisture content control of the dried sawn timber is the basis, the moisture content control of the processing is the key, and the moisture content control of the finished furniture is the target.
The production process of American furniture mainly includes: drying, batching, processing, assembly, painting and packaging of sawn timber. Therefore, the control of water content is mainly the control of the moisture content of the sawn timber. The thermostatic chamber is set before the batching, before the machine processing, before the assembly, before the coating, and before the packaging to control the water content.