Infrared thermography for monitoring surface checking of wood during drying

Abstract

Infrared thermography was used to explore more convenient ways to investigate the occurrence of checking during drying, which is indispensable for the development of the drying schedule and kiln operation. A small, constant-temperature chamber was combined with an infrared thermographic system. The occurrence of checking on cross-section was observed and the coefficient of variation of the surface temperature was measured by the system during drying. This research aimed to monitor surface checking in a wood drying process using infrared thermography, and this method is expected to a develop drying schedule. Thermographic measurement has the advantages of being non-destructive and prompt, and allowing detection over a wide area. Japanese cedar (sugi) boxed heart specimens were prepared and dried under a constant temperature of 105°C. During drying, infrared thermographic images were taken. The results indicate that the coefficient of variation of the surface temperature increased in the checked area of cross-section, whereas it decreased in the unchecked area. The change in surface temperature during drying showed some potential for detecting surface checking. Infrared thermography may be useful in the development of a kiln control system based on the surface temperature during drying.