Casting is a widely used manufacturing process that allows for the creation of parts and components of various shapes and sizes.
It involves pouring liquid metal into a mold, allowing it to cool and solidify into the desired shape. With so many different casting processes available, it can be challenging to determine the best method for a particular application.
In this article, we will explore the 11 casting processes used in manufacturing. We will also discuss the basic steps of casting production, the different types of casting materials, and how to select the right casting process.
By understanding the different casting processes and their unique characteristics, choosing the best method for a specific application and ensuring the production of high-quality parts and components will be easier.
Different Types of Casting Process
Different casting processes can be used in manufacturing, each with unique characteristics and advantages. Each of these casting processes is used in various applications depending on the requirements of the final product.
For example, sand casting is well-suited for large, complex parts, while investment casting is better for small, intricate parts.
1. Sand Casting
Sand casting is a manufacturing process in which molten metal is poured into a mold made of sand. The mold is created by compacting a mixture of sand and a binder, such as clay, into the desired shape.
Once the mold is made, the molten metal is poured into it and allowed to cool and solidify. The solidified metal object is then removed from the mold, and the process is repeated as necessary.
Sand casting is one of the oldest and most widely used casting methods and is particularly well-suited for producing large, complex parts.
However, it is relatively inexpensive and can be used to produce small quantities of parts as well. The main disadvantage of sand casting is that the surface finish of the cast parts is usually not as smooth as that of other casting methods.
2. Gravity Die Casting
Gravity die casting, also known as Permanent Mold casting, is a manufacturing process in which molten metal is poured into a reusable metal mold under the force of gravity.
The mold, also known as a die, is typically made of steel or cast iron and is heated before the metal is poured to prevent solidification before it fills the mold. Once the metal has cooled and solidified, the die is opened, and the cast piece is removed.
One of the main advantages of gravity die casting is that it produces parts with high accuracy, repeatability, and surface finish. The process is also relatively fast and efficient, making it suitable for the mass production of small to medium-sized parts.
It’s also suitable for casting alloys such as aluminum and zinc. Additionally, the dies can be used for a very long time, making it a cost-effective process.
However, gravity die casting has some limitations. The process is unsuitable for casting very large parts, and the cost of the dies can be high, especially for complex shapes.
Additionally, the process requires specialized equipment, making it less flexible than other casting methods.
3. Pressure Die Casting
Pressure Die Casting, also known as high-pressure die casting, is a manufacturing process in which molten metal is injected at high pressure into a mold cavity to form complex shapes and sizes of parts.
It is one of the most widely used processes for producing precision components that require strength, durability, and superior surface finish. Pressure Die Casting offers several benefits over traditional casting methods.
These include higher dimensional accuracy, shorter finishing times, and reduced tooling costs due to fewer machining operations needed after castings are completed.
The process uses industrial-grade dies or molds made from hardened steel or other alloys designed with specific features to create a replica part with smooth surfaces that require no further machining before final assembly.
Parts produced by this method can be found in many industries, such as automotive aftermarket products, telecommunications equipment, and medical device applications.
4. Investment Casting
Investment casting is a manufacturing process used to create high-precision and intricate detail metal castings. It involves creating wax molds of the desired product, dipping them in liquid ceramic material, then burning it off using heat or chemicals to leave a hollowed-out cavity that can be filled with molten metal.
Investment casting has higher setup costs than other processes, such as sand molding or die-casting but provides exact dimensions allowing manufacturers the capacity for close tolerance work.
Its use allows for complex shapes that may otherwise require multiple machining operations and minimizes production time by reducing material waste during manufacture and post-processing effects like cracking due to incorrect cooling rates.
The versatility of design options makes investment casting ideal for producing parts from almost any type of alloy, including aluminum, stainless steel, and carbon steel, among others, thus making this a practical option across industries ranging from aerospace components to orthopedic implants where strict adherence accuracy is required when crafting small items out of hard materials.
5. Plaster Casting
Plaster casting is a metal casting process that involves pouring molten metal into an expendable mold made from Plaster of Paris, which hardens as it cools to create a precise shape.
Plaster molds are typically simple and relatively inexpensive, making them ideal for producing complex shapes with intricate details, such as sculptures or highly detailed machine parts like engine components.
However, plaster molds are not as durable as other types of molds, and they can only be used a limited number of times before they need to be replaced.
Additionally, the surface finish of the cast parts is not as smooth as that of other casting methods.
Once the part has solidified in the mold, it is carefully removed and treated with heat treatment if desired before further processing, like machining or plating, can take place.
Plaster casting offers many advantages compared to other methods due to its low cost and flexibility while still achieving high levels of accuracy on finished parts required by most applications today.
6. Centrifugal Casting
Centrifugal casting is a manufacturing process used to produce cylindrical components with high accuracy and uniformity. The process involves pouring liquid metal into a spinning mold, typically made of metal or ceramics.
As the mold spins, the centrifugal force pushes the metal outward against the mold walls, creating a uniform thickness and density in the finished product.
The process is typically used to create parts such as pipe, cylinder liners, and gears and is well-suited for materials such as steel, aluminum, and bronze.
The advantages of centrifugal casting include high dimensional accuracy and uniformity, excellent surface finish, and the ability to create complex shapes.
However, the process can be limited by the size and shape of the component and can be more expensive than other casting methods.
7. Lost-Foam Casting
Lost-foam casting (LFC) is an evaporative-pattern casting process that uses a foam pattern embedded in a bed of unbonded sand. The foam pattern is made by expanding a polystyrene foam pattern using a gas, such as pentane or carbon dioxide.
The foam pattern is then coated with a refractory material, such as ceramic or resin, to form a shell. The shell and foam pattern are then placed in a flask filled with unbonded sand, and molten metal is poured into the flask.
The foam pattern evaporates, leaving a cavity in the sand filled with the molten metal to form the desired casting.
The process is well-suited for producing complex geometries, thin walls, and internal cavities. LFC also allows for excellent surface finish and dimensional accuracy, as well as reducing the need for core boxes and other tooling.
It’s also eco-friendly as it reduces or eliminates the use of binders, coatings, and release agents.
However, LFC is limited by the type of metal that can be used (low melting point metals such as aluminum, zinc, and copper) and the size of the casting that it can produce.
It also requires a high level of skill and experience to achieve good results, and the cost of making foam patterns can be high.
8. Vacuum Casting
Vacuum casting, also known as vacuum-assisted casting, is a manufacturing process that uses a vacuum to create high-quality castings with fine details and a smooth surface finish. The process involves pouring liquid resin into a master mold and then placing the mold inside a vacuum chamber.
The vacuum removes any trapped air bubbles and pulls the liquid resin into all the fine details of the mold, resulting in a high-quality casting with excellent surface finish and dimensional accuracy.
Vacuum casting is well-suited for small-scale production runs of complex and detailed parts, such as prototypes, medical devices, and jewelry.
The process can also be used to produce low-volume plastic parts, and it’s also a good option for creating small-scale models or prototypes of products.
The process is relatively fast, and the materials used are relatively inexpensive.
However, it has some limitations: the size of the parts that can be produced is limited, and the materials that can be used are limited to thermoplastic resins. And the process is not suitable for large-scale production runs.
9. Squeezing Casting
Squeeze casting is a manufacturing process that combines the benefits of both casting and forging. It involves injecting molten metal into a mold under high pressure, resulting in a final product with improved mechanical properties such as higher strength and better surface finish than traditional casting methods.
The process also reduces porosity and improves the dimensional accuracy of the final product. Squeeze casting is commonly used for producing high-strength aluminum and magnesium alloy parts, such as engine blocks, gears, and wheels.
The process is also suitable for producing other metal components such as titanium and steel. The high-pressure injection of metal into the mold allows for a rapid solidification rate, resulting in the final product’s finer microstructure.
This process is also known as high-pressure die casting or liquid metal forging.
10. Continuous Casting
Continuous casting, also known as strand casting, is a manufacturing process used to produce long, continuous metal shapes such as bars, rods, and tubes. It is a highly efficient method for producing large quantities of a single product and is commonly used in the production of steel and other metals.
The process begins with melting the metal in a furnace, and then the molten metal is poured into a casting mold. The mold is designed to shape the metal into the desired final product, and as the metal cools and solidifies, it is continuously withdrawn from the mold in a steady stream.
The resulting product is a long, continuous piece of metal that can be cut to the desired length for further processing or use. Continuous casting is a cost-effective and efficient method for producing large quantities of metal products and is widely used in the steel and other metal industries.
11. Shell Molding
Shell molding is a type of casting process that is used to produce complex and precise parts for a variety of industries. The process involves creating a thin shell of sand and binder around a pattern, which is then heated and cured to form a hardened mold.
The mold is then filled with molten metal, which is allowed to cool and solidify before being removed from the mold.
One of the main advantages of shell molding is its ability to produce parts with very fine details and tight tolerances. The process also allows for the creation of complex and irregular shapes that may be difficult to achieve with other casting methods.
Additionally, shell molding is a relatively low-cost process compared to other methods, making it a popular choice for manufacturers. It is commonly used in the automotive, aerospace, and medical device manufacturing industries.
Basic Steps of Different Casting Production
Casting is a manufacturing process that involves pouring liquid metal into a mold and allowing it to cool and solidify, creating a casted part.
There are many different types of casting processes, each with its unique characteristics and steps. However, some basic steps are common to most casting processes.
- Design and Pattern Creation: The first step in any casting process is to create a design and pattern for the desired part. This pattern is typically made of wood, metal, or plastic and is used to create the mold for the casting.
- Mold Creation: The next step is to create the mold for the casting. The mold is typically made of sand, metal, or other materials and is shaped to match the pattern of the desired part.
- Pouring the Metal: Once the mold is ready, the liquid metal is poured into the mold. The metal is heated to its melting point and poured into the mold under gravity or using a vacuum.
- Cooling and Solidifying: After the metal is poured into the mold, it is allowed to cool and solidify. The cooling time will vary depending on the type of metal and the size of the casting.
- Removing the Mold: Once the metal has cooled and solidified, the mold is removed to reveal the finished casting. The casting may then be cleaned, finished, and inspected for defects.
- Heat Treatment: Some castings must be heat-treated to improve their mechanical properties before final machining.
- Final Machining: The final step is to machine the casting to its final dimensions and shape.
It is important to note that the above steps are a general guide, and the specific steps and procedures will vary depending on the casting process used.
How Many Types of Casting Materials are There?
Many different types of materials can be used in casting, each with its unique properties and characteristics. The following are some of the most common materials used in casting.
- Metals: Metals such as aluminum, steel, and iron are the most commonly used materials in casting. They have high strength and durability and can be used to create a wide range of parts and products.
- Alloys: Alloys are combinations of two or more metals. They are used to create parts that have specific properties, such as corrosion resistance or high strength. Some common alloys used in casting include bronze, brass, and stainless steel.
- Ceramics: Ceramic casting is used to create brittle, heat-resistant, and wear-resistant parts. These materials are typically used in furnace liners and heat exchangers.
- Polymers: Polymers are a type of plastic used in casting. They are used to create parts that are lightweight and have a low cost. They are commonly used in toys, packaging, and household items.
- Glass: Glass casting is used to create transparent, heat and chemical-resistant parts. These materials are typically used in applications such as optical lenses and laboratory equipment.
- Composites: Composite materials combine two or more materials with different properties. They are used to create parts with unique properties such as high strength and low weight. They are commonly used in the aerospace and automotive industries.
It is worth noting that some casting processes are more limited in the types of materials that you can use, and some materials may be better suited to specific casting processes.
Therefore, choosing the appropriate material and process for a specific application is important.
How to Select the Right Casting Process
When selecting a casting process, there are several factors to consider, including design complexity, material selection, and casting cost.
- Design Complexity: The complexity of the desired part plays a significant role in determining the appropriate casting process. For example, sand casting is well-suited for large, complex parts, while investment casting is better for small, intricate parts.
- Material Selection: The type of metal or alloy used in the casting process will also have an impact on the choice of casting method. For example, aluminum and zinc alloys are typically die-cast, while iron and steel are more commonly sand-cast.
- Cost of Casting: The cost of the casting process should also be considered when selecting the appropriate method. For example, sand casting is generally less expensive than investment casting, but investment casting produces a higher-quality finished product.
Ultimately, the best casting process will depend on the specific requirements of the application and the trade-offs between design complexity, material selection, and casting cost.
Careful consideration of all these factors will help to ensure that the appropriate casting process is selected for a given application.
Outsource Your Casting Needs to Kemal
We at Kemal Precision are a trusted source for all your casting needs. With our advanced manufacturing capabilities and wide range of casting processes, we can create unique parts to support any application that you have in mind.
Whether it be gravity-assisted sand or precision die castings, we at Kemal Precision have the experience and expertise to provide high-quality products for every budget and timeline.
Our experienced team offers personalized service tailored to your needs, ensuring satisfaction in quality assurance and on-time delivery, making us the ideal choice when outsourcing manufacturing castings.