Precision casting is currently a high-quality processing method for steel bodies, but if errors occur in the processing process, it will affect the finished castings. The more common one is the phenomenon of sand formation on the surface of the castings. Let's discuss the reasons for the formation of sands below. .

The ferrous silicate condensed during the manufacturing process of precision casting has strong adhesion to precision castings, coatings and sand. It can firmly adhere the sand on the surface of the casting and form a series of low melting point compounds (in the thick wall of the casting). And corners, etc., low melting point, many sticky sand layers)

Sand formation on the surface of carbon steel precision castings is caused by the oxidation of molten steel. Traditional casting coatings only play a role of barrier and isolation between the casting and the mold to achieve the purpose of preventing sand sticking, but sometimes sand sticking to the casting part or large area. This is due to metal oxides produced by the oxidation of high-temperature liquid metals. The main product is ferrous oxide with a melting point of 1370°C. The silicon oxide reacts chemically with the SiO2 of the molding sand to produce ferrous silicate. The melting point of ferrous silicate is extremely low, only 1220°C, so it has good fluidity. Even if there is a solidified shell on the surface of the casting, the newly produced ferrous silicate is still liquid and easily penetrates the coating into the sand hole.

The above is an analysis of the causes of sand formation on the surface of precision casting castings.