Circular Tube Forming by Using Extrusion of Wood Powder Combined with Sucrose and Citric Acid

Wood materials are attracting attention as an alternative material to plastics for solving environmental problems, such as sea microplastic. An effective wood processing method should be developed for producing products with various shapes, which leads to an effective use of the wood. This paper proposed extrusion of the wood powder mixed with a natural binder composed of sucrose and citric acid, which effectively forms products with same cross-sectional shape in the extruding direction. Circular tube was extruded in this experiment. It was important to solidify the wood powder inside an extrusion die for molding the tube without cracks and fracture. Therefore, influence of the extrusion die length, the punch speed and the heating temperature, which concern solidification with cooling, were investigated for improving the dimensional accuracy and the mechanical property of the tube. At first, the fracture of the molded product was prevented by setting an appropriate die length. High punch speed caused the tube expansion due to insufficient cooling before extruding, while low punch speed caused the fracture due to long time heating. Density and strength of the molded product increased with the decrease in the temperature, although the cracks easily occurred on the tube surface under the low temperature of 140°C. The tube surface state became smooth by setting the molding temperature to 160 or 180°C. From the above results, the circular tube, which has good dimensional accuracy and mechanical property, was molded by controlling the extruding condition.