Evaluation the effect of kiln schedule on warp and surface checking in beech (fagus orientalis Lipsky) at 5 cm thickness

In this research, beech (fagus orientalis Lipsky) lumbers at 5 cm thickness were ran domically selected and commercially cut down from sari region(Neka choob company), with three schedule namely T5-C3, T5-C4, T6-C4 were adapted for drying the lumbers down to the final moisture content of 8% to evaluation the effect of kiln schedule on warp and surface checking. primary dry bulb temperature each three schedules was adjusted at 49 °C and the final dry bulb temperatures was adjusted at 71, 71 and 82°C respectively. Basic Specific gravity and dry specific gravity were measured 0.52 and 0.61 respectively. Longitudinal, radial, tangential and volumetric shrinkage were measured 0.46 %, 5.8%, 10.2%, 16.46% respectively. Quantity of defect s including crook, bow, twist and three longest surface checks of the lumber were measured before and after the drying process in each stage. In order to analysis the lumber defects for estimating the best schedule, quality control graph were used. In the end, results of investigation indicated that drying of beech lumber by using of the three schedules was desired. However the third schedule (T6-C4) had better drying characteristics than the other schedules.