Sand casting is the most popular and simplest type of casting that has been used for centuries. Sand casting is used to make large parts such as gray cast iron, ductile iron, stainless steel and other types of steel. The main steps include painting, mold, core making, modeling, melting and pouring, cleaning, etc.
The traditional method is to obtain the casting drawings and then send the drawings to the foundry. This process can be completed in the quotation. Nowadays, more and more customers and foundries use computer-aided design instead.
In sand casting, the mold is made of wood or other metal materials. In this process, we ask our engineers to make the mold size slightly larger than the finished product, and the difference is called the shrinkage allowance. The purpose is that the molten metal acts on the mold to ensure that the molten metal solidifies and shrinks, thereby preventing voids during the casting process.
The core is made only by placing resin sand particles in a mold to form a casting on the inner surface. Therefore, the gap between the core and the mold eventually becomes cast.
A pair of molds needs to be prepared during the smelting and molding process. Molding usually involves the support frame of the mold, pulling out the mold to separate it during the casting process, melting the previously placed core in the mold and closing the mold opening.
The purpose of cleaning is to remove sand, sand, and excess metal in castings. Welding and sand removal can improve the surface appearance of castings
The burnt sand and scale are all demolished to improve the surface appearance of the casting.Excess metal and other risers are removed. One step closer to welding, polishing and other steps. Finally, check its defects and comprehensive quality.
Reprocess before shipment. According to the requirements of different customers, we can do heat treatment, surface treatment, additional inspections and so on.
Selection Of Pouring Position
- The important processing surface of the casting should be facing down or on the side.
- The broad plane of the casting should face downwards.
- The thin-walled part with a larger area should be placed in the lower part of the mold or in a vertical, inclined position.
- For castings that are prone to shrinkage, the thicker section should be placed on the upper or side.
- The number of cores should be reduced as much as possible, and it is easy to place, fix and vent.
Selection Of Mold Parting Surface
1)It is easy to draw the mold and simplify the modeling process.
- The selection of parting surface should avoid loose blocks and cores as much as possible to simplify the process of mold making, modeling and molding.
- In order to facilitate the extraction of the mold, the parting surface should be selected at the source of the largest section of the casting.
- The parting surface should be as straight as possible and the number should be small.
- Try to make the casting have only one parting surface, so as to adopt two-box modeling with simple modeling process.