Casting is an essential part of metalworking that involves melting metal materials and pouring them into a mold to create complex shapes or parts for different applications.
It is commonly used for various applications, such as the automotive, aerospace, and healthcare industries.
There is a wide variety of casting processes, and each has its unique advantages and disadvantages depending on the intended use of the cast part.
So, in the following sections, we will discuss 11 types of casting processes used in manufacturing today.
This type of information is especially useful for businesses seeking to understand the intricacies of the different casting processes and the ways in which they can benefit their custom metal projects.
During centrifugal casting, molten metal is poured into a rotating mold.
As the mold rotates, it creates a centrifugal force that pushes the metal against the mold’s walls creating a hollow shape with a uniform wall thickness.
Therefore, the process is often used to create cylindrical metal shapes such as pipes, tubes, and rings.
The centrifugal casting process has several advantages, including the ability to produce dense and defect-free castings with excellent mechanical properties.
The uniform wall thickness also provides consistent and predictable mechanical properties throughout the casting.
Another major benefit of centrifugal casting is that it can be used with a wide range of alloys and metals, including aluminum, copper, bronze, and stainless steel.
The steps involved in the centrifugal casting process typically include:
Overall, centrifugal casting is a great method for producing high-quality metal parts with a consistent and uniform structure.
In continuous casting, there is a constant feeding of molten metal into a mold as the previous cast solidifies.
This method is used primarily to produce long, flat, or round continuous shapes like rods, tubes, and sheets.
The process is efficient, fast, and cost-effective and, consequently, one of the most widely used casting processes in the steel industry.
It is mostly used in the production of metals such as steel, copper, and aluminum.
The process involves four main steps:
One of the main advantages of continuous casting is its ability to produce metal products with a more uniform grain structure, which leads to improved physical and mechanical properties.
In addition, continuous casting tends to be more environmentally friendly than other casting methods, since it requires less energy and produces fewer emissions.
The continuous casting process is efficient, cost-effective, and reliable. Furthermore, it produces materials with fewer impurities and at faster speeds than traditional casting methods.
It also requires less human labor and energy consumption, making it an excellent choice for environmentally conscious businesses.
Gravity casting (or permanent mold casting) uses a metallic mold cavity to receive and cool down molten metal through the force of gravity.
In other words, during this process, molten metal flows into the mold under the influence of gravity, as opposed to being forced in by external pressure.
Allowing the liquid metal to flow into the mold instead of pushing it in through using external force allows for the casting of small to medium-sized parts that are both high in accuracy and have an aesthetic and durable surface finish.
The steps of the process are as follows:
Perhaps, the most unique feature of gravity casting is its ability to produce parts with a smooth surface finish and excellent dimensional accuracy.
Since gravity casting produces parts with low porosity and minimal shrinkage, it is great for making components that are not only structurally sound, but also have excellent surface finishes.
An additional advantage of this process is that it can also produce large quantities of parts at a fair price and with minimal waste.
The applications of gravity casting are many, and include automotive and aerospace parts, household appliances, and industrial machinery components.
Overall, the gravity casting process is an excellent choice for large-scale projects that require complex designs, as well as for projects that require small and intricate parts with a high-quality finish.
Investment casting (also known as lost-wax casting) is used to create complex and intricate parts with a high degree of accuracy.
The process can be used to manufacture a wide variety of products, ranging from aerospace components to jewelry pieces.
It involves creating a wax pattern of the desired part or product and applying several layers of ceramic material around it.
The exact steps of the investment casting process can be seen below:
Investment casting offers several advantages over other manufacturing techniques.
First, there is its ability to produce intricate and complex parts with high accuracy and consistency.
Second, it can create parts with smooth finishes and tight tolerances without requiring extensive machining or post-processing, resulting in cost and labor savings.
Investment casting provides a higher level of accuracy and detail than many other casting methods.
Because of this, it is one of the most preferred casting processes for manufacturing complex metal components.
It is also not limited by size or shape, giving it greater flexibility in design and making it a good choice for aerospace, automotive, and medical applications.
The process of lost foam casting utilizes expandable foam patterns to create metal parts.
Expandable foam is lightweight, easy to work with, and can be easily shaped and molded into any desired form during the casting process.
The entire process consists of multiple parts, which can be broken down into the following four steps:
Through the above steps, the ability to produce complex shapes, high dimensional accuracy, and the elimination of parting lines is garnered.
Lost foam casting is very useful for the production of engine blocks, cylinder heads, and other automotive components, as well as in the manufacture of various household items, including kitchen appliances and tools.
Plaster casting and investment casting, while similar, differ in several ways.
To begin with, plaster casting involves creating a mold out of plaster, which is then filled with molten metal, while investment casting uses a wax pattern that is coated in a ceramic slurry and then heated to remove the wax and create a hollow ceramic mold.
The plaster used during plaster casting can form an exact shape of the molded replica and so is an excellent tool for creating intricate and detailed metal parts. Gypsum-based plaster is used.
This method is relatively simple and involves only three steps:
Perhaps the biggest advantage of plaster casting is its ability to use a wide range of metals.
Bronze, aluminum, zinc, magnesium, and other copper alloys are some of the low-melting and non-ferrous materials that work well with this process.
Due to its ease of use, a process requiring minimal steps, supplies, and materials, and the ability to produce molds in a variety of shapes and sizes, plaster casting has become a popular manufacturing method in various fields.
These include art, medicine, and engineering.
Furthermore, plaster casting is often used in the production of jewelry, dental appliances, prosthetic limbs, orthopedic devices, and the production of other small, high-precision parts.
Pressure casting (i.e., high-pressure die casting) utilizes high pressure to force molten metal into a reusable steel mold or die.
Once in the die, the liquid metal is rapidly cooled and solidified, resulting in a precise and accurate shape.
This type of casting is an excellent method for producing high-volume, complex parts that require close tolerances and smooth surface finishes.
The steps of the pressure casting process are as follows:
There are several advantages of pressure casting.
First, it can produce metal parts with complex shapes with high accuracy.
Next, it has high production rates.
Additionally, it produces excellent surface finishes.
Finally, the process is almost entirely automated. In other words, it allows for more efficient production of large quantities of parts.
Pressure casting has a wide range of applications, for instance, in the production of automotive parts, electronic components, and aerospace parts.
Also, due to its high production rates and excellent surface finishes, it is commonly chosen for parts that require tight tolerances and high levels of consistency.
Sand casting derives its name from the sand mold that is created during the process to create a desired shape.
The sand used in this process is held together with a binder (clay) that is typically made from a mixture of silica, water, and other additives.
There are six steps in the entire process.
These include:
One of the most sought-after characteristics of sand casting is its versatility. It can be used to create intricate and complex shapes in a variety of sizes.
Sand casting is also a relatively inexpensive process, and therefore can be used by businesses on a budget for both small and large production runs.
The process is also well-known for its fast turnaround times. In fact, it is one of the fastest casting methods used in today’s manufacturing industry.
As with most of the other casting methods, sand casting too has numerous applications across various industries (e.g., automotive, aerospace, and construction).
The most common products manufactured via sand casting include engine blocks, gears, and pump housings.
Sand casting offers an economical and efficient way to produce custom metal parts out of both ferrous and non-ferrous metals.
Shell mold casting is similar to sand casting but instead of plaster, it uses a resin-coated mold to create a more precise and accurate casting.
The resin that is typically used during the process is phenol formaldehyde.
The process of shell casting is as follows:
Shell mold casting offers three distinctive casting features in the form of higher dimensional accuracy, smoother surface finishes, and the ability to produce intricate parts with thin walls.
Thinner walls offer reduced weight, greater flexibility in design, and improved efficiency of materials.
Another advantage to using shell mold casting over other casting methods is that it can be used for a wide range of alloys, including steel, aluminum, and bronze.
The shell mold casting process is ideal for the production of metal parts used in the aerospace, automotive, and medical industries.
This process is an excellent choice for creating parts with thin walls or sections, such as those found in turbine blades, impellers, and housings for various mechanical devices.
The accuracy and precision of shell mold casting make it a preferred method for the creation of critical components where quality and precision are paramount.
Squeeze casting combines the advantages of both casting and forging.
During this process, molten metal is poured into a preheated die, where it is closed off before pressure is applied to the metal as it solidifies.
The pressure applied is typically between 50 and 140 MPa (lower than forging, higher than die casting), making the process ideal for producing parts with complex shapes and tight tolerances.
The steps of the squeeze casting process include the following:
The die used in squeeze casting is typically made of steel, and designed to create the desired shape of the part.
Squeeze casting’s benefits to businesses seeking metal parts are multifold.
The process can produce metal components with excellent surface finish, high strength, and high ductility.
Furthermore, it allows for reduced porosity, which tends to result in better mechanical properties of metal parts.
This casting method is often used to manufacture parts for the automotive, aerospace, and military industries, as well as for high-performance sporting equipment.
It is also used in the production of parts for medical and power generation equipment.
Since squeeze casting offers the benefits of both casting and forging methods, it is one of the best choices for producing metal parts with high levels of component precision.
Vacuum casting (also referred to as vacuum mold casting or V-process) uses a vacuum to create a mold.
The vacuum extracts air from the mold so that the liquid material can fill it evenly.
This method is widely employed for creating small batches of parts that require a fine surface finish, excellent dimensional accuracy, and intricate designs.
Vacuum casting is also ideal for creating castings that are free of defects.
The steps of the process are outlined below:
Through the above steps, high-quality, detailed castings with a smooth surface finish are created.
One of the main objectives of vacuum casting is to eliminate the need for a gating system, thus reducing the amount of material needed and minimizing the amount of finishing work required.
Aside from being cost-efficient, vacuum casting is also highly time efficient.
The process has a short cycle time and provides the ability to reuse the mold multiple times.
Vacuum casting is currently used in the production of small to medium-sized parts in the automotive, aerospace, and medical industries.
It is particularly useful for creating parts with intricate and minute details, such as gears, impellers, and housings.
When it comes to choosing the right casting process for your custom metal project, knowledge is key.
Not knowing enough can greatly impact the quality, cost, and overall success of your product.
By understanding the 11 different types of casting processes discussed in the above sections, you can make a more informed decision as to which one will best suit your manufacturing needs.
Yet, with so many casting options to choose from, it might still be hard to make a final decision.
Therefore, it is still a good idea to consult with a custom metal manufacturing expert to better navigate the sometimes rather complex manufacturing selection process.
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