The combined use of atmospheric drying and other drying methods can give full play to the advantages of low cost and simple operation of atmospheric drying, combined with the advantages of fast speed of other drying methods, and can achieve very satisfactory economic results. The two-stage drying that is often used in production is an example of combined drying. The so-called two-stage drying means that the sawn timber is dried to a moisture content of 20% in the first stage in the lumber mill; Process drying to the desired final moisture content.