Metal casting methods are divided into two types: traditional and modern. A detailed explanation follows.
Traditional Metal Casting Methods
Traditional casting is a metal casting method that forms cast products using sand molds. What does traditional casting entail? It is classified into two types: wet sand mold (green sand mold) and dry sand mold.
Wet sand mold (Green sand mold)
Green sand molding sand is a type of molding sand that is created by combining several materials, including quartz sand as a base material, bentonite (clay) as a binder, and several other materials that are added to produce specific properties in the molding sand.
To activate bentonite in the sand binding process, a certain amount of water is added when mixing, and when pouring metal liquid into the mold, it still contains water; as a result, this molding sand is often referred to as wet molding sand.
The ratio of each component that makes up green sand molding sand varies greatly depending on its use and has gone through trial and error stages. Green sand molding is made up of the following ingredients:
- Quartz sand customized to your specifications
- Bentonite: 7.5%-9%
- Water: 3.7% – 4.5%
- Additional materials such as carbon dust function to increase the surface smoothness of castings.
Dry sand mold
A dry sand mold is molding sand that does not contain water when metal liquid is poured into the mold. The CO2 process, cement process, no-bake process, and resin cold box are all included in a dry sand mold.
1. CO2 Process
CO2 process molding sand is a mixture of new silica sand, glass water (Na2 SiO3. H2O + CO2), and added material in the form of molasses to increase the crushing power of printed sand when dismantling.
When blown by CO2 gas, glass water acts as a binder, hardening into crystals. As a result, it is known as the CO2 process. The reaction occurs when CO2 gas is blown through glass water (crystallization).
Na2 SiO3. H2O + CO2 ——-> SiO2 . H2O + Na2 CO3
2. Cement process
The cement process is a type of sand molding that uses a mixture of sand, cement, and water. In addition, molasses was added to speed up the hardening of the sand.
The cement process molding sand is nearly identical to the building mix that uses Portland-type cement; the difference is that the cement process molding sand uses more sand and less cement and water.
The process of hardening cement by allowing it to stand in free air for 24 to 48 hours, depending on the percentage of the composition.
3. No-Bake Process
Molding sand for the no-bake process is made up of quartz/silica sand, a liquid resin binder (furan or phenol), and a catalyst as a hardener. Because the hardening process occurs when the resin is mixed with the catalyst, the time available for sand molding is extremely limited. The setting takes about six hours until the maximum hardness is reached, and parts of the pattern can be removed after 0.5 to 1 hour.
4. Resin Coldbox
Resin cold box sand molding is made up of quartz/silica sand, phenol or polyisocyanate resin, and trimethylamine or dimethylamine catalyst. The hardening process begins after the sand is exhaled as a catalyst by gas.
Modern Metal Casting Methods
Modern casting is a metal casting technique that does not use molding sand in the casting process. So, what is included in modern casting?
- Investment Casting
- Lost Foam Casting
- Die Casting
- Centrifugal Casting
- Tilt Casting
- Squeeze Casting
- Continuous Casting
In the following article, we will go over an explanation of these modern casting methods. So, stay tuned!