Sand casting is the most popular and simplest type of casting, which has been used for centuries Sand casting is used to manufacture large parts, such as gray cast iron, nodular cast 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 casting drawings and send them to the foundry. This process can be completed in the quotation. Nowadays, more and more customers and foundry manufacturers use computer-aided design to replace.
In, the mold is made of wood or other metal materials. In this process, we ask our engineers to make the die size slightly larger than the finished product, and the difference is called shrinkage allowance. The purpose is that the molten metal acts on the mold to ensure the solidification and shrinkage of the molten metal, so as to prevent cavities in the .
As long as the core is made by placing resin sand particles in the mold to form a casting with an internal surface. Therefore, the gap between the core and the mold eventually becomes casting.
A pair of molds need to be prepared in the melting and forming process. Molding usually involves the supporting frame of the mold, pulling out the mold to separate it during the casting process, melting the previously placed core in the mold, and then closing the mold mouth.
The purpose of cleaning is to remove sand particles, grinding and excess metal in castings. Welding and desanding can improve the surface appearance of castings
The burnt sand and scale were removed to improve the surface appearance of the casting. Excess metal and other risers are removed. Take another step, such as welding and grinding. 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 inspection, etc.
Selection of pouring position
(1) The important machined surface of the casting shall face down or on the side.
(2) The wide plane of the casting shall face down.
(3) The thin-walled part with large area shall be placed at the lower part of the mold or in a vertical and inclined position.
(4) for castings prone to shrinkage cavity, the part with thick section shall be placed on the upper or side.
(5) The number of small cores shall be reduced as far as possible, and it shall be easy to place, fix and exhaust.
Selection of parting surface of mold：
1) It is convenient to lift the mold and simplify the molding process.
(1) The selection of parting surface should avoid movable block and core as far as possible, so as to simplify the process of molding, modeling and closing.
(2) In order to facilitate mold lifting, the parting surface shall be selected at the source of the largest section of the casting.
(3) The parting surface shall be as straight as possible and less in number.
(4) Try to make the casting have only one parting surface, so as to adopt two box molding with simple molding process.
2) Try to put the important machining surfaces or most of the machining surfaces and machining datum planes of the casting in the same sand box
3) Try to keep the cavity and main core in the lower box.