Preparation of coated sand for selective laser sintering and optimization of baking process of sand moulds

A cold method was used to prepare coated sand for application in the selective laser sintering(SLS)process. Tensile strength, loss on ignition, gas evolution, and accuracy of the SLS samples were tested and analyzed, and the baking process was thoroughly investigated. Compared with coated sand prepared by the hot method, the cold method yields a more uniform and complete resin film on the sand's surface, resulting in enhanced tensile strength and accuracy. Additionally, the cold method requires a lower binder content to meet the same strength requirements, thereby minimizing gas evolution, reducing porosity defects, and ultimately improving casting quality. The coated sand samples prepared through the cold method exhibit superior accuracy,with a size error of within ±0.4 mm. In contrast, the coated sand samples prepared by the hot method display a lower accuracy, with an average negative error of 2.1993 mm. The highest tensile strength could be attained by controlling the baking temperature within a suitable range(180-190 °C), which can effectively reduce the generation of gas, thus contributing to improved overall performance.