Casting is most commonly used to create complex shapes that would otherwise be difficult or uneconomical to make using other methods. Metal casting processes have been known for thousands of years, and have been widely used for creating sculptures, jewelry, transportation, weapons, and tools.
What is casting?
Casting is a manufacturing process in which a liquid material is usually poured into a mold that contains a cavity of the desired shape and then allowed to solidify. The solidified part is also known as the casting, which is ejected or broken from the mold to complete the process. It has a wide range of applications including industrial manufacturing, automotive, and aerospace industries.
The basic metal casting process involves creating a pattern and a mold, then pouring molten metal into the mold. You will then extract the solid metal casting and finish your piece. This process is customizable for different types of metal casting, along with shapes, sizes, and more.
Types of casting
1. Sand casting
Sand casting, also known as sand casting and sand casting, usually relies on silicon-based materials, such as synthetic sand and natural sand. Foundry sand usually consists of finely ground spherical particles that can be tightly packed together to form a smooth surface. Castings reduce the likelihood of tearing, cracking or other defects through flexibility and shrinkage during the cooling stage of the process. Sand can also be strengthened by adding clay to help the particles bind more tightly.
Low mold cost
Wide range of uses
Ideal for making complex shapes, especially those with internal cavities
The finished product has low precision
Rough surface of casting
High cost of cleaning and processing
Application: It is often used to make crankshafts, cylinder heads and castings of automobile engine blocks.
2. Lost wax casting
Lost wax casting, also known as investment and lost wax method, uses a wax mold coated with a ceramic material to harden the wax mold into the shape of the casting. Once the ceramic solidifies, the wax melts and the molten metal is poured into the cavity, and as the metal solidifies, the casting will crack and break out of the metal part.
High dimensional accuracy
Good surface finish
Parting lines are barely visible
Ability to create intricate shapes
Reduce processing costs
High production cost
Each mold can only be used for one casting
Castings are limited in size
Application: Commonly used to produce small parts with complex shapes, such as turbine engine blades.
3. Vacuum die casting
Vacuum die casting is mainly used to cast high-strength, corrosion-resistant aluminum bronze. By controlling the vacuum, the pressure differential between the mold cavity and the molten metal can be varied, allowing for different fill rates required by part design and pouring requirements. Tight control of the fill rate can enhance casting stability. With proper part, mold design, and vacuum processing, voids, shrinkage, and air pockets in critical areas can also be greatly reduced and eliminated. Because the sprue is submerged under the surface of the molten metal, only pure alloy free of oxides and slag can enter the cavity, which helps produce clean, sound castings.
Good surface finish
High dimensional accuracy parts
Reduce voids and air bubbles in die castings
Higher cost compared to die casting
Appropriate controls are required to produce the desired results
Application: This casting method is commonly used in the automotive industry, especially for chassis forming.
4. Die casting
Die casting is a method of forming materials under high pressure, solidifying semi-solid or commercial metals under high pressure, metals usually involving non-ferrous metals and alloys such as zinc, tin, copper and aluminum.
Tight dimensions and high form tolerances
Reduce post-processing such as machining
High dimensional consistency of manufactured parts
High quality castings
High mold cost
Long delivery time
Die castings have low plasticity
Not all metal alloys can be die cast
Application: This casting technology is usually used in the automotive, machine tool, and electronics industries.
5. Lost foam casting
Lost Foam Casting, also known as Foam, Solid Mold Casting, is primarily the use of polystyrene or copolymers that are expanded in an aluminum tool and glued together to form a finished model or parts assembled into a foam model, and finally the parts are glued form a finished product. Although it is not as widely used as other processes, lost foam casting offers advantages for making intricate patterns to create machined foam patterns in a completely model-free casting that is not feasible with other processes.
Very complex products can be cast
Very smooth surface
More environmentally friendly
Short processing cycle
High cost of making patterns
Easily damaged or deformed
Application: Commonly used to make fire hydrants, valves, cylinder blocks, motor starters, etc.
6. Continuous casting
Continuous casting, also commonly known as "continuous casting", is an improvement on the casting process for continuous mass production of metal profiles with constant cross-sections. The principle is to rapidly cool the metal to the freezing point, and the rapid cooling in the mold can ensure that the solidified metal has a fine, uniform grain structure, which has more physical properties than sand castings. After solidification, the cast bar is cut to the desired length.
Capable of producing high quality metal
Promote the production of standardized steel castings
Mechanized operation can reduce labor costs
Casting size and structure are easy to control
Only simple castings can be produced
Continuous cooling is required throughout the process
High investment cost
Requires a larger footprint
Application: The common continuous casting shapes in production are tubular and solid, of course, other shapes can also be produced, such as square, rectangular, hexagonal and other irregular shapes.