Advantages of resin sand casting and defect analysis of resin sand castings

Advantages of resin sand casting and defect analysis of resin sand castings

Advantages of resin sand coating

Casting coatings are improvements and adjustments based on traditional casting coatings, which can prevent oxidation of high-temperature liquid metals and prevent chemical reactions during the contact between the mold and high-temperature liquid metals. And can absorb and digest gases such as nitrogen, sulfur, and carbon.

Thus solving problems such as sand sticking, sand holes, roughness, porosity, inclusions (slag), deterioration of ductile iron, sulfurization cracks in cast steel, and carburization defects.

The main products include: gray cast iron parts, ductile iron parts, heat-resistant castings, alloy castings, etc.

Principle analysis of defects such as sand sticking, porosity, and sand holes in castings

The reason why castings stick to sand is because the coating cannot act as a barrier or isolation, or the coating will react chemically with high-temperature metal liquids.

1. Poor adhesion of paint: During sand filling vibration, the paint peels off, causing sand sticking to the casting.

2. High coefficient of expansion of coating: When the coating comes into contact with high-temperature molten metal, the volume of the coating expands and leaves the mold, causing sand sticking to the casting.

3. High temperature liquid metal is oxidized and reacts chemically with the coating and mold to form metal oxides, which have adhesion to both the coating and sand. They can firmly attach the sand to the surface of the casting, forming a series of low melting point compounds (there are many low melting point substances in the thick walls and corners of the casting, after the sand layer), leading to sand sticking in the casting.

Casting trachoma:

1. Sand falls into the mold.

2. The coating has low strength, poor fire resistance, and cannot withstand the erosion of high-temperature metal liquid. There is molding sand in the casting.

Casting porosity: There are many reasons, and a common one is that the mold contains a large amount of gas, which produces gas. The permeability of paint or sand is poor, and the gas is not discharged in a timely manner.

Precision machining