Green sand molding is a sand mold that is commonly used in metal casting processes. Because the sand used in this mold still contains water when the molten metal is poured into it, it is also known as a wet sand mold. Green sand molding is used in ferrous castings weighing up to 200 kg for FC and 150 kg for FCD. The following is an in-depth explanation of the material, properties, and advantages of this molding.
Green sand molds are made from this material
Sand
When selecting sand for green sand molding, the size of the sand grains, grain distribution, grain shape, heat resistance, and silica content must all be considered. The most commonly used sand is silica sand, which has a high heat resistance and is inexpensive.
Bentonite clay
Bentonite is a soft rock formed from volcanic material that has been buried for millions of years and has undergone an acid or alkaline process. Bentonite is a type of clay primarily composed of Montmorillonite.
The element carbon
The use of carbon in green sand molds is intended to:
• Prevent molten metal penetration.
• Casting surface that is smooth.
• Reduced sand expansion damage.
• Reducing mold deformation to minimize potential shrinkage damage.
• Make the disassembly of the mold easier.
• Strengthening and stabilizing green sand.
Flour
Flours are used to improve the properties of molding sand, making it more elastic, resistant to erosion/abrasion, and compensating for silica sand grain expansion.
Water
Water is an essential component in the creation of green sand molds because it acts as a force activator in green sand. Water contains elements that have an impact on bentonite. Water with a high salt content, for example, can reduce bentonite’s electrostatic bonding.
Green Sand Mold Properties
Flowable
During compaction, green sand must be able to fill all parts of the mold and pattern surface.
Elasticity
Green sand must be able to deform slightly without cracking so that the pattern can be easily removed.
Green power
Green sand must be strong enough to be lifted from the pattern, withstand the weight of the sand without changing, and withstand the pressure of the liquid metal when poured.
Gas flow capable
Since the pouring process begins, gas and steam can easily escape from the mold.
Dry strength
To avoid molten metal erosion during the pouring process because the water content will drop on the mold’s surface.
Resistance to heat
High liquid metal temperatures can be tolerated without burning the sand and causing casting defects.
The Advantages of Green Sand Mold
The prices are affordable
This mold is made of materials that are inexpensive and easily obtained. These materials can be found in abundance in nature, such as river sand and water.
Eco-friendly
Green sand molding is not only inexpensive, but it is also environmentally friendly because it can be recycled. Green sand molds that have been recycled can be used to create new molds.
High productivity
Green sand mold processing is simple but time-consuming. As a result, the output can be quite large. Production can be increased, especially if it is done with a molding machine.
Flexible in molding processes
Molding can be done manually, semi-automatically, or automatically. The molding process is carried out by hand. Part of the molding process is done by hand, and part of the process is done by machine. While the entire molding process is done automatically by machine.