14 Types of Casting: The Ultimate Guide

Different Types of Casting Process

Types of the casting process

There are several types of casting that are typically categorized as follows:

① Common Sand Mold Casting, which has three types: Wet Sand Casting, Dry Sand Casting, and Chemical Hardening Sand Casting.

② Special Casting, which can be divided into two categories based on the modeling material: casting that uses natural mineral sand as the main modeling material (such as Investment Casting, Clay Casting, Shell Casting, Negative Pressure Casting, Full Mold Casting, Ceramic Mold Casting, etc.), and casting that uses metal as the main modeling material (such as Metal Mold Casting, Pressure Casting, Continuous Casting, Low-Pressure Casting, Centrifugal Casting, etc.).

We will discuss the definitions, characteristics, advantages, and disadvantages of each of these casting processes in more detail.

By reading this information, you will gain a better understanding of casting technology.

1. Sand casting

Sand casting

What is sand casting?

Sand casting is a method of producing castings in a sand mold, and it is capable of producing castings made of steel, iron, and most nonferrous alloys.

Technological process:

Technological process

Sand casting process

Technical characteristics:

This method is suitable for producing blanks with complex shapes, particularly those that have intricate inner cavities. It has a wide range of adaptability and is cost-effective.

Sand casting is the only viable process for producing parts or blanks with materials that have poor plasticity, such as cast iron.

It finds applications in producing castings like automotive engine blocks, cylinder heads, crankshafts, and other similar components.

2. Investment casting

Investment casting

What is investment casting?

Investment casting is a casting process that involves creating a pattern from a fusible material, encasing it in multiple layers of refractory materials, melting the pattern out of the mold to obtain a parting-surface-free mold, and then filling it after baking at high temperatures.

Technological process:

Technological process

Investment Casting Process

Advantages:

  • High dimensional accuracy and geometric accuracy;
  • High surface roughness;
  • It can cast complex castings, and cast alloys are not restricted.

Disadvantages: complicated procedures and high cost

Applications:

Investment casting is suitable for producing small parts with complex shapes and high precision requirements, or for parts that are difficult to process, such as turbine engine blades.

3. Clay mold casting

Clay Mold Casting: A Casting Method Using Clay as the Main Material

Clay mold casting is a traditional casting process that uses clay as the primary material to create a mold for producing castings.

To create a strong cohesive force, the clay is mixed with water and materials such as rice husk, rice awn, horse dung, and chaff ash. After air-drying or sun-drying, the clay forms a mold with air outlet pores and high hardness.

The surface of the clay mold is fine and uniform, while the texture in the middle is coarse. Additional materials such as sand, tank slag, and broken bricks may be added. The clay mold can be used multiple times, making it a semi-permanent mold.

Clay mold casting is the earliest known casting technology used in China.

4. Shell casting

Shell Mold Casting is a process that produces castings using thin shell molds. It was invented by German J. Cronin in 1943 and first used in Germany in 1944. Since then, it has been adopted by other countries as well.

The process involves covering a metal formwork heated to 180-280°C with heat-hardened molding sand, typically phenolic resin-coated sand, to create a thin shell mold with a thickness of 6-12mm. The mold is then heated to solidify it, providing the necessary strength and stiffness.

Once the upper and lower mold shells are clamped or glued with resin, the mold can be formed without a sand box. The metal formwork used for casting is typically heated to around 300°C, and the molding sand used is resin sand, which is made with phenolic resin as the binder.

Additionally, the core can also be made into a thin shell core using the same method as creating a thin shell casting mold. The blowing method is commonly used to manufacture the thin shell core.

5. Ceramic mold casting

Ceramic Mold Casting is a casting method that utilizes a ceramic slurry to produce castings. The slurry comprises ethyl silicate hydrolysate and fine refractory sands, such as fused quartz, zircon, and corundum, known for their pure texture and high thermal stability.

To expedite the gelling of the ceramic slurry, calcium hydroxide or magnesium oxide is often included as a catalyst.

Due to the similarities in composition and appearance between the refractory used and ceramics, this process is often referred to as a “ceramic type” casting. Ceramic Mold Casting is a new technology that has developed from traditional sand mold casting.

There are two types of ceramic mold casting:

① The ceramic mold is produced by applying the ceramic slurry to the molding board, coating the sand box, pouring the adjusted slurry into the sand box, and lifting the mold after bonding and hardening. The mold is then baked at high temperature to form the casting mold.

② The casting mold is created by pouring the ceramic slurry into the gap between the bushing and the pattern, using a bushing made of either sand or metal. This method of using a bushing can save a significant amount of ceramic slurry and is widely used in production.

6. Metal mold casting

Metal Mold Casting, also known as Hard Mold Casting, is a process in which liquid metal is poured into a metal mold to create castings. The mold is made of metal and can be reused multiple times, ranging from hundreds to thousands of cycles.

However, Metal Mold Casting has certain limitations on the weight and shape of castings that can be produced. For instance, ferrous metals can only be used to produce castings with simple shapes, and the weight of the casting must not be too heavy.

Furthermore, the wall thickness is limited, which makes it challenging to cast smaller castings.

7. Die casting

Die casting

What is die casting?

The high-pressure metal liquid is pressed into a precision metal mold cavity at high speed, and the metal liquid is cooled and solidified under pressure to form a casting.

Technological process:

Technological process

Advantages:

  • The metal liquid is subjected to high pressure andthe flow rate is fast during die casting.
  • Good product quality, stable size and good interchangeability.
  • High production efficiency and die casting molds can be used for many times.
  • It is suitable for mass production with good economic benefits.

Disadvantages:

  • The casting is prone to produce fine pores and shrinkage.
  • The die-casting parts have low plasticity and should not work under impact load and vibration.
  • When die casting of high melting point alloy, the life of the mold is low, which affects the expansion of die casting production.

Applications:

Die castings were first applied in the automotive industry and the instrument industry, and then gradually expanded to various industries, such as agricultural machinery, machine tool industry, electronics industry, national defense industry, computers, medical equipment, clocks, cameras and daily hardware.

8. Low-pressure casting

Low pressure casting

What is low pressure casting?

Low pressure casting refers to the method of making liquid metal fill a mold under a low pressure (0.02 – 0.06MPa) and crystallize under pressure to form a casting.

Technological process:

Technological process

Technical characteristics:

The pressure and speed during pouring can be adjusted, making it suitable for various casting molds, such as metal and sand molds, and for casting various alloys and castings of different sizes.

By adopting a bottom-injection filling method, stable filling of the metal liquid is ensured, without any splashing. This helps prevent the presence of gas and reduces the erosion of the mold walls and core, thereby improving the casting pass rate.

The casting solidifies under pressure, resulting in a dense structure, sharp outline, smooth surface, and high mechanical properties. This process is particularly beneficial for casting large, thin-walled parts.

It eliminates the need for risers and increases the metal utilization rate to 90-98%. Furthermore, it is characterized by low labor intensity, good working conditions, simple equipment, and a high potential for mechanization and automation.

Application: 

Mainly used in traditional products (cylinder head, hub, cylinder frame, etc.).

9. Centrifugal casting

Centrifugal casting

What is centrifugal casting?

It is a casting method in which molten metal is poured into a rotating mold, and the mold is filled and solidified under the action of centrifugal force.

Technological process:

Centrifugal Casting Technological process
Centrifugal Casting Technological process

Advantages:

The pouring system and riser system consume minimal metal, leading to an improved process yield.

In the production of long tubular castings, the absence of a core enhances the metal filling ability significantly.

The resulting casting exhibits high density, few defects (such as pores and slag inclusions), and excellent mechanical properties.

Manufacturing composite metal castings of barrels and sleeves is relatively easy.

Disadvantages:

  • There are certain limitations when used in the production of specialshaped castings.
  • The diameter of the inner hole of the casting is not accurate, the surface of the inner hole is rough, the quality is poor, and the machining allowance is large.
  • The casting is prone to specific gravity segregation.

Applications:

Centrifugal casting was initially utilized for producing cast pipes, but it has since been widely adopted in various industries such as metallurgy, mining, transportation, irrigation and drainage machinery, aviation, national defense, and the automotive industry. This process is used to produce steel, iron, and non-ferrous carbon alloy castings.

Centrifugal casting finds its most common applications in the production of centrifugal cast iron tubes, cylinder liners for internal combustion engines, and shaft sleeves.

10. Gravity die casting

Gravity die casting

What is gravity die casting?

Gravity Die Casting is a casting process where liquid metal is poured into a metal mold under the influence of gravity, cooled, and solidified to produce a casting.

Technological process:

Gravity die casting Technological process

Advantages:

The metal mold boasts high thermal conductivity and heat capacity, resulting in a rapid cooling speed and a dense casting structure. Moreover, it has mechanical properties that are approximately 15% higher than sand casting.

Using a metal mold allows for the production of castings with greater dimensional accuracy and lower surface roughness, thereby enhancing quality stability.

In addition, the use of sand core is minimal or non-existent, leading to improved environmental conditions by reducing dust and harmful gases, as well as lowering labor intensity.

Disadvantages:

  • The metal mold itself is non-breathable, and certain measures must be taken to evacuate the air and air generated by the sand core in the cavity.
  • The metal mold has no concession, and cracks are easy to occur when the casting is solidified.
  • Metal molds have a longer manufacturing cycle and higher cost.Therefore, good economic effects can only be shown when mass-produced.

Applications:

Metal casting is a suitable method for large-scale production of non-ferrous alloy castings, such as aluminum alloys and magnesium alloys, with complex shapes. It can also be used for producing iron and steel metal castings and ingots.

11. Vacuum die casting

Vacuum die casting

What is vacuum die casting?

Vacuum die casting is an advanced form of die-casting that improves the mechanical properties and surface finish of cast parts by removing or significantly reducing the pores and dissolved gases within them. This is accomplished by extracting gas from the mold cavity during the casting process.

Technological process:

Vacuum die casting Technological process

Advantages:

  • It can eliminate or reduce the air holes inside the die casting, improve the mechanical properties and surface quality of the die castingas well as the plating performance.
  • To reduce the back pressure of the cavity, lower specific pressure and alloy with poor casting performance can be used. It is possible to die-cast larger castings with small machines.
  • It improves filling conditions, can cast thinner castings.

Disadvantages:

  • The mold sealing structure is complicated, making and installing is difficult, so the cost is high.
  • If the vacuum die casting method is not properly controlled, the effect will not be very significant.

12. Squeezing die casting

Squeezing die casting

What is squeezing die casting?

Squeeze casting is a process that involves solidifying liquid or semi-solid metal under high pressure and flow forming to produce the final product or blank directly. This process offers several benefits, including high utilization of liquid metal, a simplified process, and consistent quality.

Furthermore, it is an energy-efficient metal forming technology that holds great promise for future applications.

Technological process:

Squeezing die casting Technological process

Direct squeezing die casting: 

Spray paint, cast alloy, mold clamping, pressurization, pressure holding, pressure relief, mold separation, blank demolding and resetting.

Indirect squeezing die casting: 

Spray coating, mold clamping, feeding, filling, pressurization, pressure holding, pressure relief, parting, blank demolding, resetting.

Technical characteristics:

  • It can eliminate the internal pores, shrinkage andother defects.
  • Low surface roughness and high dimensional accuracy.
  • It can prevent the occurrence of casting cracks.
  • Easy to realize mechanization and automation.

Application: 

It can be used to produce various types of alloys, such as aluminum alloy, zinc alloy, copper alloy, nodular cast iron, etc.

13. Lost foam casting

Lost foam casting

What is lost foam casting (also known as solid casting)?

Lost foam casting is a modern casting technique that uses a combination of paraffin or foam models, which are created to resemble the desired cast in both size and shape. These models are then clustered together to form a single unit.

The model cluster is coated with a refractory material, dried, and subsequently buried in dry quartz sand that is subjected to vibration.

Liquid metal is then poured into the sand under vacuum conditions, causing the model to vaporize, and the metal takes its place. Once the cast has solidified, it is cooled to form the final product.

Technological process: 

Pre-foaming → Foaming molding → Dip coating → Drying → Modeling → Pouring → Falling sand → Cleaning

Lost foam casting Technological process

Technical characteristics:

  • High precision casting, no sand core, reducing processing time.
  • No parting surface, flexible design and high degree of freedom.
  • Clean production without pollution.
  • Reduce investment and production costs.

Applications:

Lost foam casting is a suitable method for producing a variety of precision castings that feature complex structures in different sizes. It offers great versatility, with no limitations on the types of alloys used or the size of production batches.

This method has been successfully used to produce a range of castings, including gray cast iron engine blocks and high manganese steel elbows.

14. Continual casting

Continual casting

What is continual casting?

Continuous casting is a sophisticated casting process that involves pouring molten metal continuously into a special metal mold called a crystallizer. The solidified casting is then continuously drawn out from the opposite end of the mold, enabling the production of castings of any length or specific length.

Technological process:

Continual casting Technological process

Technical characteristics:

The rapid cooling of the metal results in denser crystal structures, uniformity, and improved mechanical properties, while also saving metal and increasing yield.

This process simplifies procedures by eliminating the need for modeling and other steps, reducing labor intensity and significantly minimizing the necessary production space.

Moreover, continuous casting is easily automated, which increases production efficiency due to its ease of mechanization.

Applications:

Continual casting can be used to cast steel, iron, copper alloys, aluminum alloys, magnesium alloys and other long castings with constant cross-sectional shapes, such as ingots, slabs, rod billets, pipes, etc.

What is the casting process?

Casting is a processing technique where solid metal is melted and then poured into a mold of a specific shape to solidify. The result, also known as a cast, is removed from the mold once it has solidified, completing the casting process.

Casting is a process in which metal is melted to meet specific requirements and then poured into a mold. The result is a solid casting with a predetermined shape, size, and performance after cooling, solidification, and cleaning.

casting process

Because the casting is nearly formed, machining is reduced or not necessary, resulting in a lower cost and shorter manufacturing time.

Casting is a fundamental process in modern manufacturing industry.

The casting process usually includes the following:

① Preparation of the Casting Mold: The casting mold is made to contain the solid casting and can be divided into different types based on the material used, such as sand molds, metal molds, ceramic molds, clay molds, and graphite molds. The number of uses of the mold can also determine its classification as a one-time mold, semi-permanent mold, or permanent mold. The preparation of the casting mold is the most significant factor that affects the quality of the castings.

② Melting and Pouring of the Casting Metal: The casting metal, also known as casting alloy, primarily includes cast iron, cast steel, and cast non-ferrous alloys.

③ Casting Treatment and Inspection: This process involves several steps, such as removing foreign matter from the core and casting surface, eliminating sprues and risers, removing burrs, cracks, and other projections, heat treatment, shaping, anti-rust treatment, and rough machining.

Most casting materials are metals, including copper, iron, aluminum, tin, lead, etc., which are heated to a liquid state from their solid form. The casting mold materials can be sand, metal, or ceramics, and the method used will vary based on the requirements.

Casting is one of the earliest metal hot-working processes known to humans, with a history dating back about 6000 years.

The metals that can be cast include copper, iron, aluminum, tin, and lead, while the materials used for ordinary casting molds can be raw sand, clay, water glass, resin, and other auxiliary materials.

Some examples of special casting molds include investment casting, lost foam casting, metal mold casting, ceramic mold casting, among others. (Raw sand may include quartz sand, magnesia sand, zirconium sand, chromite sand, forsterite sand, kyanite sand, graphite sand, iron sand, among others.)

Technological process: liquid metal → filling → solidification shrinkage → casting

What is casting

Casting process characteristics:

  • It can produce parts with any complicated shape, especially those with complicated inner cavity shapes.
  • Strong adaptability, unlimited alloy types and almost unlimited casting size.
  • Wide source of materials, waste can be remelted, and equipment investment is low.
  • High scrap rate, low surface quality and poor labor conditions.

How can I cast parts at home?

To begin casting, you will require a device that is capable of melting either iron or aluminum. If your daily production is low, it is advisable to invest in a small-capacity electric furnace. An older furnace may even suffice.

Kerosene furnaces are also suitable for melting aluminum.

It is important to note that iron and aluminum cannot be melted in the same furnace as it can make it challenging to regulate the material.

However, if material control is not a requirement, it may not be an issue.

Next, you will need a mold that can be custom-made according to the parts you want to cast. You will also require sand, and a sand mixer is recommended. If you do not purchase a sand mixer, manual mixing is possible.

With these simple modeling tools, you can mold, melt, and pour, creating the casting blank.

Lastly, you will need cleaning tools to remove the pouring riser and smooth out any burrs. Adding a shot blasting roller can enhance the appearance of the casting.

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Shane
Author

Shane

Founder of MachineMFG

As the founder of MachineMFG, I have dedicated over a decade of my career to the metalworking industry. My extensive experience has allowed me to become an expert in the fields of sheet metal fabrication, machining, mechanical engineering, and machine tools for metals. I am constantly thinking, reading, and writing about these subjects, constantly striving to stay at the forefront of my field. Let my knowledge and expertise be an asset to your business.

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