Investigation on the cryogenic cutting performance of birch

In wood cutting, reducing the temperature during cutting can improve machining accuracy and quality. However, traditional coolants are not suitable for reducing the cutting temperature of wood because they will contaminate the machined surface of the wood and affect the health of the operator. Supercritical carbon dioxide (ScCO${}_2$) cooling technology is one of the ways to solve such problems, as ScCO${}_2$ is a sustainable energy technology that can bring high efficiency, environmental protection, and cost-effectiveness. Dry turning and ScCO${}_2$ turning tests were carried out on birch, respectively, to compare the results of cutting temperature, cutting force and surface roughness characteristics during the process, and to study the cutting performance of ScCO${}_2$ turning of birch. The results show that the cutting depth has the greatest influence on the cutting temperature and cutting force during dry cutting and cryogenic cutting. ScCO${}_2$ turning compared with dry turning, the temperature of the cutting area decreases, the cutting force increases. As the cutting temperature is reduced, the brittleness of the wood fibers improves, and the degree of elastic–plastic deformation produced by the action of the cutting tool is smaller, resulting in a decrease in surface roughness and obtaining better machined surface quality. Moreover, under dry cutting conditions, the surface roughness $R_a$ decreases and then increases with the increase of cutting speed; under ScCO${}_2$ cutting conditions, both the cutting force and surface roughness $R_a$ decrease with the increase of cutting speed. Therefore, under the premise of obtaining the same cutting quality, cryogenic cutting can use higher machining speed, which helps to improve machining efficiency. This study analyzes the machining performance of turning birch under ScCO${}_2$ conditions to provide theoretical and application references for the application of ScCO${}_2$ in the field of wood cutting processing.