After the wood drying room starts, the wood is preheated first. Before preheating, the equipment inside the drum and the shell should be heated to about 30 ° C to prevent moisture condensation. The aim of pre-heat treatment is to make the temperature and humidity rise to the required medium state at the same time and keep a certain time to make the wood heat permeate. During the preheating process, the moisture on the wood surface generally does not evaporate and a small amount of moisture absorption is allowed.
In the process of wood drying, according to the size of wood drying stress in time to be dried wood intermediate treatment. The aim of intermediate treatment is to eliminate drying stress and surface hardening of wood section, and to prevent internal cracking and deformation of wood during drying.
The moisture content of equilibrium treated self-drying wood begins when it reaches the low value of the allowable final moisture content and ends when the moisture content of wet wood reaches the high value of the allowable moisture content. The aim of equilibrium treatment is to improve the uniformity of drying and moisture distribution along the thickness of the whole stack.
When the wood is dried to moisture content, final treatment is carried out. The aim of final treatment is to eliminate the uneven distribution of moisture content in wood cross section and to eliminate residual stress. Required drying quality of grade 1,2 and 3 wood, must be carried out end-of-life treatment.