Different types of metal casting processes used in manufacturing industries are mentioned below.
Types of casting process;
- Sand casting
- Shell mold casting
- Plaster mold casting
- Ceramic mold casting
- Investment casting
- Vacuum casting
- Permanent mold casting
- Slush casting
- Pressure casting
- Die casting
- Centrifugal casting
- Continuous casting
- Squeeze casting
Let me tell you a few important things about all these types of casting processes.
Types of Casting Process
As mentioned above, there are mainly 13 different types of casting process.
Here I have given the description of each of these metal casting processes one by one.
So let’s dive right into it.
#1) Sand casting
- Sand casting (which is also known as sand molded casting) is a type of casting process in which the molding sand is used as a mold material.
- Molding sand is cheap and it has high refractoriness which can withstand the high temperature of molten metal.
- Almost 70% of all the castings are manufactured by using a sand casting process.
For more information on sand casting process, see the detailed guide on sand casting. (Where you will see the detailed sand casting process, its advantages, disadvantages as well as applications.)
#2) Shell mold casting
- In sand mold casting, the process is similar to that of the sand casting process, but the difference is that the molten metal is poured in an expendable mold.
- In shell mold casting process, the thin walled shell is made by applying a sand resin mixture around the pattern.
- Generally the pattern used in shell mold casting is made up of metal, so that it can be reused.
- By using the shell mold casting process, parts like camshaft, connecting rods, gears, cylinder heads, etc can be manufactured.
- Shell mold casting is applicable for both ferrous and non-ferrous metals. Cast iron, alloy steel, carbon steel, stainless steel, copper alloys and aluminum alloys are the commonly used metals for shell mold casting.
For more information on shell mold casting process, see the detailed guide on shell mold casting. (Where you will see the 6 steps of shell mold casting process, its advantages, disadvantages as well as applications.)
#3) Plaster mold casting
- Plaster mold casting is similar to sand casting, but the difference is of the molding material.
- In sand casting, the molding material is sand, while in plaster mold casting, the molding material is Plaster of Paris (POP).
- Plaster mold casting process is mostly used for casting of non-ferrous metals.
- Small castings of 30 gram as well as large castings of 45 kilograms can also be manufactured by using a plaster mold casting process.
For more information on plaster mold casting process, see the detailed guide on plaster mold casting. (Where you will see the step by step detailed process, its advantages, disadvantages as well as applications.)
#4) Ceramic mold casting
- Ceramic mold casting is similar to the plaster mold casting process.
- In ceramic mold casting, the refractory ceramic is used as a mold material.
- Because of this refractory ceramic material, it can cast metals at high temperature.
- Metal molds, metalworking dies, as well as machining cutters can be manufactured by using this type of casting process.
- Ceramic mold casting process is used for casting the ferrous metals and other metals having high melting point.
If you want more information on ceramic mold casting process, then see the detailed guide on ceramic mold casting. (Here you will see the detailed ceramic mold casting process, its advantages, disadvantages as well as applications.)
#5) Investment casting
- Investment casting (also known as lost wax process) is a process in which a wax pattern is coated with a refractory ceramic material.
- As the refractory material gets hardened, it’s internal geometry takes the shape of the wax pattern.
- The wax is then melted out and the molten metal is poured into the mold cavity.
- This molten metal solidifies and the outer ceramic material is broken down to take the casting out.
- By using investment casting, parts like dental fixtures, cams, turbine blades, gears, jewelry, as well as other components with complicated shapes can be manufactured.
If you want more information on investment casting process, see the detailed guide on investment casting. (Where you will see the step by step process of investment casting process, plus its advantages, disadvantages as well as applications.)
#6) Vacuum mold casting
- Vacuum mold casting (which is also known as V-process) is a casting process in which the mold cavity holds the shape of the casting due to forces exerted by the vacuum pressure.
- Thin walled profiles can be made with good accuracy using vacuum process.
- The mechanical properties of casting obtained by this process is 10 to 15% better than castings obtained by the gravity process.
- Vacuum casting process is used for manufacturing the jobs with smaller weight (i.e from 0.2 kg to 5 kg).
- The disadvantage of vacuum process is that the tooling cost is higher.
- The mold used in the vacuum casting process has short life. If steel or iron is used in vacuum casting process, then the mold life becomes extremely small. This is because steel and iron have higher melting temperatures.
For more information on vacuum mold casting process, see the detailed guide on vacuum mold casting. (Where you will see the step by step procedure along with its advantages, disadvantages and applications.)
#7) Permanent mold casting
- Permanent Mold Casting process (also known as Metal Mold Casting process) is a metal casting process which uses permanent molds (or reusable molds) that are usually made of metal.
- In simple words, the mold in which the molten metal is to be poured is made up of metal (and not sand).
- Permanent metal mold casting method is used for casting metals like aluminum, magnesium, and copper alloys.
- Metal like zinc, tin, iron, steel and lead alloys are also casted in graphite molds.
- Various parts like gears, engine pistons, pipe fittings, wheels, gear housing, etc can be manufactured using permanent mold casting.
If you want more information on the permanent mold casting process, see the detailed guide on permanent mold casting. (Where you will see its step by step procedure along with its advantages, disadvantages and applications.)
#8) Slush casting
- Slush casting process is a type of permanent mold casting process in which hollow castings are manufactured.
- In slush process, the molten metal is poured in the metal mold as shown in the above image.
- This molten metal is allowed to cool for a very short time such that only outer surface metal gets solidified.
- The excess molten metal is then poured out of the hollow shell. (See above image).
- And finally, the hollow casting is obtained when the halves of mold are separated.
- The wall thickness of the casting may vary because of unequal solidification.
- Slush casting process is generally used for manufacturing ornamental products, lamp bases, hollow statues, etc.
- In slush casting, the metals having lower melting point are prepared.
- The main advantage of slush casting is that it uses less material as compared to that of solid casting. Thus the final casting is lighter and cheap.
- Generally, most of the hollow castings have a small hole from where the excess molten metal is poured out.
For advantages, disadvantages and applications of slush casting, visit the main article on Slush casting.
#9) Pressure casting
- Pressure casting (or low pressure permanent mold casting) uses a low pressure gas (between 20 kPa to 100 kPa) to push the molten metal into the mold cavity.
- As shown in the above image, the low pressure is applied to the top part of the molten metal, and due to this, the molten metal rises up in the refractory tube and finally reaches the mould cavity.
- The refractory tube is kept deeper in the molten metal so that clean molten metal is pushed to the mould cavity.
- There is no wastage of molten metal as there is no runner and riser used in this process. The excess molten metal falls back to the ladle which can be reused.
- Low pressure permanent mold casting is generally used for aluminum castings, magnesium castings and for some copper alloys.
- Because of the constant pressure during the filling of molten metal, there is a low turbulence and it minimizes gas porosity.
If you want more information on pressure casting process, see the detailed guide on pressure casting. (Where you will see its step by step procedure along with its advantages, disadvantages and applications.)
#10) Die casting
- Die casting is a type of permanent mold casting process in which a large amount of pressure is applied to the molten metal that forces it to flow in the mold cavity.
- Because of the large amount of force applied to the molten metal, high accuracy can be achieved on the final casting product.
- The die used in the die casting process is made up of metal.
- The mass of the die is kept far greater than the mass of the casting.
- Due to the large amount of pressure and direct contact of the molten metal, wear of die may occur.
- But if the die casting process is done in a maintained and controlled way, then it can last up to hundreds of thousands of cycles.
For more detailed information about the die casting process, visit this main article “Die casting“, where I have explained step by step procedure of die casting, its advantages, disadvantages as well as applications.
#11) Centrifugal casting
- Centrifugal casting is a metal casting process in which centripetal acceleration is used to distribute the molten metal in the mold.
- Schematic diagram for the centrifugal casting process is shown in above image.
- Centrifugal casting is generally used for manufacturing of cylindrical castings like rings, pipes, bushings, brake drums, liners of engine cylinders, etc.
- The molds are round and are generally made of iron, graphite or steel.
- The refractory material is also added to the mold surface to prevent thermal damage due to extreme heat of molten metal.
For more detailed information on centrifugal casting, visit the main article “centrifugal casting“, where I have discussed the entire process with its types, its advantages and disadvantages, as well as its applications.
#12) Continuous casting
- As the name suggests, the continuous casting process is used to cast a continuous length of metal.
- The schematic diagram for continuous casting process is mentioned in the above image.
- The molten metal is constantly supplied to the mold at correct rate so that the solidification also takes place at the same time interval.
- Precise calculations are required for the manufacturing of castings by using continuous casting process.
- This type of casting process is used to manufacture long slabs from aluminum, copper or steel.
Visit main article on continuous casting for detailed information with advantages, disadvantages and applications.
#13) Squeeze casting
- In squeeze casting process, the molten metal is poured into the preheated die.
- After this, during the solidification process of the molten metal, the pressure is applied from the top as shown in image.
- The applied pressure is less than that used in forging.
- By using a squeeze casting process, castings having good details can be manufactured.
- This type of casting is used for both ferrous metals as well as in ferrous metals.
Casting core: Image by Vinodh Reddy Chennu, CC BY-SA 2.5, via Wikimedia Commons
Permanent casting example: Image by Janke, CC BY-SA 2.5, via Wikimedia Commons
Slush process: Image source (Science direct)
Low pressure casting: Image by Wizard191, CC BY-SA 3.0, via Wikimedia Commons
Centrifugal casting: Image by Користувач:Shkod, CC BY-SA 3.0, via Wikimedia Commons