This paper proposed molding of wood powder with natural binder, which is composed of sucrose and citric acid, for effectively fabricating wood product without synthetic resins. In the proposed method, optimization of particle size is important for improving the thermal fluidity during the molding and reducing the milling cost. Thermal flow testing of wood powder with natural binder was carried out in order to investigate the effect of particle size on thermal flow of wood powder with natural binder. When binder content was 30~40 wt%, the thermal flow pressure changed depending on the particle size, and the optimum one was the particles, which passed 2.8 mm mesh sieve and be on 2.0 mm mesh sieve, for decreasing the flow pressure. In a case that the particle size was smaller than the optimum size, the flow pressure increased because the slipping plane propagation was prevented. In the case that the particle size was larger than the optimum size, the flow pressure also increased due to an increase in the force for crashing the particles. Based on the results of thermal flow testing, molding testing was carried out. When the particle size was optimum, products were fabricated successfully in a wide range of binder content, which was 30~50 wt%, because the flow pressure was low.
