Evaluating Kiln Drying Schedules for Poplar Pood with 7.5 cm THickness from North Khorasan Area

In this research, 15 m3 of poplar (Populus nigra) lumber with 7.5 cm thickness cut down from cultivated grounds of Shirvan Town in North Khorasan province was dried with kiln-drying schedules T5-D2 (Forest Product Laboratory), T5- D3 and T7-D3 in semi-automatic kiln with final moisture content of 8±2%. Then the effect of kiln-drying schedules on warp and surface checks of the lumber was evaluated in order to reach the least time for drying for having the desired wood quality. Primary dry bulb temperature of each three schedules were adjusted at 49,49,and 54°C and the final dry bulb temperatures was adjusted at 71°C. The defect of warp, bow and surface checks in the lumbers were measured before and after the drying process in each stage. In order to analyse the lumber defects for estimating the best schedule the quality control graph was used. Results of study showed that the desired schedule was drying of poplar lumbers by using T5-D2 and T5-D3 schedules. However, the first schedule (T5-D2) showed better drying characteristics (humidity gradient, quality and quantity of lumbers than the other schedules).