Our company produces a ship inspection casting with a contour size of 1650mm for a certain shipping company × 2210mm × 1962mm; Process weight 36t, steel liquid volume 58.7t, cross-sectional area 1773mm × 1650mm. The use of furan resin sand core molding can ensure the overall dimensional requirements of the casting and the certification requirements during the ship inspection process.

(1) The molding process involves multiple tests on other similar products, using Foxconn ISOMOL300 alcohol based coating to produce castings. During the operation, the surface quality of the sand core is strictly controlled, and three layers of 2.0mm coating are applied uniformly. During the painting process, the first layer dilutes the coating to ensure that most of the aggregates and carriers penetrate into the gaps of the sand mold during the first painting. By utilizing the characteristics of the coating, the strength and fire resistance of the sand mold are increased. After ignition, the surface burned coating, droplet marks, and brush marks are polished; The second layer adjusts the viscosity of the coating by increasing it to ensure the thickness of the coating, as the brushing layer can play a fire-resistant role, which is the key sequence for the occurrence of sand sticking in the casting; During the third coating, adjust the viscosity of the coating to be between the first and second layers of the ice head. The main purpose of this coating is to adjust the overall coating to ensure a smooth and even surface of the sand mold to ensure the appearance quality of the casting.

Control points for the brushing process: First, mix the paint in the paint bucket evenly in the mixer, and then dilute it with alcohol according to the specified proportion. Stir evenly again, and after the coating is still, use a Baume meter to measure the Baume degree of the coating to the appropriate value. Stir for 10 minutes every 2 hours during use. When brushing, the Baume degree should be controlled between 75-85 and the density should be between 1.81-1.85kg/L. Pour the mixed paint into a dedicated volume for easy portability. Choose different brushes based on the size or shape of the casting surface. When brushing, choose the correct brushing sequence to prevent accumulation and uneven brushing. For dead corners or areas such as navels and rib plates that are prone to accumulation, brush multiple times to ensure that the surface of the sand core is smooth and flat, the edges are clear, and the size and shape are correct. Eliminate brush marks and flow marks. The coating thickness should be ensured to be 0.5-1mm, and the areas prone to sand sticking should be coated with at least three coats of paint. After the completed sand core is assembled and combined into a box, the overall mold cavity is baked. Due to the fact that some coatings of the mold may absorb moisture during the mixing process, which may affect the performance of the coating, it is necessary to use an electric heating drying device to bake the mold cavity 24 hours before pouring the sand mold. In the first stage, dry at 150-170 ℃ for 8 hours to ensure that the moisture in the mold cavity migrates to the outside of the mold with heat, while also avoiding excessive temperature that may cause the coating layer to peel off locally from the sand mold due to rapid heating. The second stage is drying at 180-200 ℃ for 12 hours. The reason for increasing the drying temperature is to dry the deep moisture on the surface of the mold. Due to the mold cavity having a certain temperature, it avoids the phenomenon of rapid thermal peeling.