Surface sand sticking defect refers to the adhesion of a layer of sand particles on the surface of steel castings that are difficult to remove. Wet mold clay sand cast steel workpieces are mostly mechanical sand sticking defects, and occasionally mechanical chemical sand sticking defects. Mechanical sand sticking defect is that the metal liquid penetrates into the sand gap and adheres the sand to the surface of steel castings after solidification. High content of alkaline oxides in raw sand may induce chemical sand sticking defects. The pouring temperature of steel castings is high. When the quartz content of raw sand is too low, the molding sand becomes thinner after repeated use, and the mud content is too high, the surface sand sticking defect is easy to occur when the fire resistance of molding sand is insufficient.
The surface quality requirements of steel castings are higher and higher, and the sand sticking defect is bound to cause heavy cleaning workload. Efforts must be made to overcome the sand sticking defect on the surface, which can be improved from the following aspects: on the premise of ensuring the air permeability of molding sand, do not use too coarse raw sand, the molding sand coating shall be evenly coated, and the key parts can be coated with anti sand coating; Ensure the fire resistance of molding sand and control the mud content; Ensure the content of starch organic matter in molding sand and form a reducible peelable bonded sand layer.