Sand casting process is a thermoforming process by utilizing expendable and reusable sand to produce castings with complex geometry and structure. Since the economy of the mold material, sand casting process is the most popular casting process, and more than 70% casting components are produced via sand casting globally. Sand casting process is suitable for both ferrous metal and almost all nonferrous metal as aluminium alloy.
Preparation for Sand Casting Process
Making Patterns and Core Box
Fabricate patterns and core boxes according to the designing of sand casting. The material of patterns and core boxes is made of wood, plastic or metal. Patterns are used to make sand mold as drag and cope, while core boxes are used to make sand cores.
Mold Sand Prefabrication
Mold material for sand casting mainly consists of sand and binder. There are two kinds of mold sand: green sand and resin sand. Green sand consists of sand, clay and moisture, which is the most popular process in sand casting. Resin sand consists of sand and synthetic binder cured physically and chemically.
Sand Core Preparation
Sand core is fabricated by utilizing manual labor or machine to fill the resin sand into the sand box. After sand core is solidified, open the core box and get the sand core. Sand core is used to insert the sand mold to form the inside structure of a castings.
Metal smelting is carried out by utilizing smelting furnace to smelt metal alloy. The aim of smelting process is to get pure molten metal alloy with qualified chemical property and right pouring temperature.
A Typical Sand Casting Process
Sand Casting Process Step 1
Place casting flask over the drag pattern, and fill the prefabricated sand in the flask. Squeeze the sand with pestle, and strickle off the extra sand to get the drag.
Sand Casting Process Step 2
Turn over the drag, and assemble the cope pattern on the drag pattern with location pins. Place and locate casting flask over the cope pattern to make cope.
Sand Casting Process Step 3
Fill the prefabricated sand in the flask with the pouring pins and riser pins are fixed. Squeeze the sand with pestle, and strickle off the extra sand to get the cope.
Sand Casting Process Step 4
Disassemble cope and drag. Remove patterns, pouring pins and riser pins. Make pouring system, which includes pouring basin, sprue hole, choke, runner and gate.
Sand Casting Process Step 5
Clean up the parting plane. Insert and locate the prefabricated sand core in the drag. Assemble cope on the drag to get ready for pouring.
Sand Casting Process Step 6
Pour molten metal into the sand mold via pouring system until molten metal overflow from riser. The castings is cooled and solidified in the air condition.
Sand Casting Process Step 7
Break away the sand mold and sand core after the casting is cooled and solidified. Cut off the riser and runner on the castings. After finishing processes as heat treatment, surface treatment, CNC machining and inspection, the castings is processed to the designed component finally.
The Advantages of sand Casting Process
Mold material of sand casting process is cheap and reusable.
Sand casting process is suitable for both single-piece production and small-volume production.
Production cycle of mold for sand casting process is relatively shorter than other casting process.
Sand casting process is suitable for castings with big size and complex geometry.
Sand casting process is almost suitable for all kinds of metal, and widely applied in various industries.
The Disadvantages of sand Casting Process
Labor intensive, poor working environment, low-level automation.
Castings produced by sand casting process is normally with low dimension accuracy, poor surface roughness and high scrap rate.