Ⅰ. Introduction to sand casting
Sand casting is the most popular and simplest type of process for producing castings and has been in use for centuries. Sand casting is used to manufacture large castings, such as steel castings, gray cast iron, ductile iron, stainless steel and other types of steel.
The main steps of sand casting include painting, mold, core making, modeling, melting and pouring, cleaning, etc. The basic raw materials for making sand molds are foundry sand and sand binder. The outer sand molds used in sand casting are divided into three types: clay green sand, clay dry sand and chemical hardened sand according to the binder used in the sand and the way it builds its strength.
The most commonly used foundry sand for sand casting is siliceous sand. When the high-temperature performance of silica sand cannot meet the requirements of use, special sand such as zircon sand, chromite sand, and corundum sand are used. The most widely used molding sand binder is clay, and various drying oils or semi-drying oils, water-soluble silicates or phosphates and various synthetic resins can also be used as molding sand binders. This process is usually used in the heavy casting.
Ⅱ. Advantages of sand casting
1. Silica sand is rich in resources and cheap in price. Most of the used silica sand can be recycled and reused through the sand reclamation system;
2. The cycle of manufacturing the mold is short and the work efficiency is high;
3. The mixed molding sand can be used for a long time;
4. Sand casting has wide adaptability, small parts, large parts, simple parts, complex parts, single parts and large batches can be used.