Sand Casting

What is sand casting? Sand casting is a process that uses sand as a casting material, bonds the sand to form a sand mold, and combines it with a sand core to form a casting mold; then pours, cools, and processes to obtain a casting. Sand casting is one of the most common casting processes because the molding materials used in sand casting are cheaper and easily available; the mold is simple to make and can be used for mass production of most raw materials or single-piece production of castings. We can use sand casting to complete steel, iron, aluminum, and most non-ferrous alloy castings.

Common raw materials for sand castings:
Steel: carbon steel, stainless steel, alloy steel, cast steel.
Iron: gray iron, ductile iron, cast iron.
Aluminum: cast aluminum, aluminum alloy.
Copper: brass, copper alloy.

Types of sand casting:
Sand casting is divided into three types according to the type of sand, the binder used in the sand, and how its strength is built: clay wet sand casting, clay dry sand casting, and chemical hardening sand casting.
According to the different chemical sand molds, it is divided into water glass sand casting, resin sand casting, and coated sand casting.
Sand casting application: We can use sand casting to produce some castings with low precision requirements. In terms of the size, weight and complexity of the castings, large, small, heavy, light, complex and simple can all be manufactured using the sand casting process.

Advantages and disadvantages of sand casting:
Advantages:
1. The molding material is cheap and easy to obtain.
2. The mold is easy to make.
3. It can adapt to the single-piece production, batch production and mass production of castings.
4. Low cost, simple production process and short production cycle.
5. The weight of the casting can range from a few kilograms to tens of kilograms, while the weight of the casting produced by clay dry casting can reach tens of tons.

Disadvantages:
1. The precision is not very high.
2. Porosity: The gas does not escape in time before the metal liquid crusts, resulting in pore defects in the casting.
3. Sand sticking: There is a layer of sand on the surface of the casting that is difficult to remove, which is called sand sticking.
4. Sand inclusion: When casting thick and large flat castings with wet molds, it is easy to have grooves and scar defects on the surface of the casting.
5. Sand hole: It is a hole-like defect filled with molding sand inside or on the surface of the casting.
6. Expansion sand: It is a defect formed by the movement of the mold wall under the pressure of the molten metal during pouring, and the local expansion of the casting.