Metal casting is a popular method used in metalworking. This process usually involves liquefied metal and mold or casing, and it has been used by human civilization for thousands of years. Metal casting has been used to create different metal parts and it has become one of the most important and flexible methods of making high-quality metal parts. If you are searching for information about metal casting, you came to the right place. At SEI Castings, we will be sharing with you an article discussing what you need to know about metal casting. If you think this article is for you, we encourage you to keep scrolling below to find out. 

What is metal casting?

Metal casting is a manufacturing process used for creating metals. This process involves pouring liquefied metal into a metal mold or casing. The mold’s interior is created to have a negative impression of the part that is being manufactured so when the liquid metal cools down and becomes solid inside the mold it will take the shape of the mold or casing. Then the finished product or metal part will then be removed from the mold.

Metal casting can be classified into different types. It usually depends on the parts being made and the metals that will be used. The different varieties of metal casting come with different advantages and use different patterns, casing, filling techniques, etc. 

How does metal casting work?

The metal casting process occurs by heating a metal, placing it inside the mold or casing, allowing it to cool down and solidify, and then taking the finished product from the mold. Below is a step-by-step process of how metal casting is done. 

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  • Creating a pattern – The metal casting process will require the creation of the pattern that will be used to create the mold that will be used for the process. The pattern that will be used can be permanent or not, and can be made of different materials such as plastic, wax, or wood. 
  • Creating the core – When casting a hollow part, you have to create a core, a solid material that will be positioned inside the cavity of the mold so it will resemble the interior geometry of the metal part. For example, you will have to create a cylindrical core to use with a large cylindrical mold to produce a tube-shaped cast part.
  • Creating the mold – Molds can be created in different ways and may depend on the process that you will use. If you will create a permanent metal mold, you can use a CNC machine. If you will use a sand mold, you can apply a sand mixture to the outside of the pattern. The process of creating molds is also known as mold making. 
  • Filling the mold – The chosen metal alloy will be subjected to high temperatures until it liquefies, then it will be poured inside the mold. For example, if you will use high-pressure die casting, the molten metal will be forced inside the mold or casing using high pressure then high clamping forces will be applied to secure the die. While in gravity casting, the molten metal will be poured downwards into the mold. 
  • Removing the part – Allow the molten metal to cool down and solidify, then you can remove it from the mold. When using a permanent mold, the two halves of the mold will be separated to remove the metal part and it will be reused again for the same process. In sand casting, the sand mold will be destroyed to get the metal part inside. 
  • Post-processing – Depending on the cast metal parts that will be used, it may be required to be cleaned thoroughly after the process. It will be done by removing the remaining materials inside or outside the mold. 

What are the advantages of metal casting?

  • Applicable for mass production
  • Can be used to manufacture big and heavy metal parts
  • Can be used to create thick-walled metal parts
  • Suited for creating large parts
  • Excellent for using light metal alloys
  • Can be used with different metal materials

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What are the limitations of metal casting?

  • Limited dimensional accuracy
  • Unpreventable defects (can occur during production)
  • Labor intensive
  • High minimum order quantities are required

What are the different types of metal casting?

Die casting

One of the most popular types of metal casting, die casting is recommended for creating intricate and detailed metal parts. This process uses two reusable tool steel dies as tooling. Its process is the same as plastic injection molding. The molten metal will be forced inside the mold using high pressure. This process is useful in manufacturing metal parts with fine details. The cost of the creation of custom dies can be expensive, so it is a recommended process for the mass production of metal parts. Once the metal dies are created, they can be reused a lot of times. Die casting produces metal parts with a great surface finish. The most common metals used for die casting is Aluminum and Zinc. 

Gravity casting

This metal casting type uses a reusable metal mold. This process uses gravity to move the liquefied metal through the mold from top to bottom. The molds used for gravity casting is preheated and usually made of cast iron because it has low thermal fatigue. 

Sand casting

This metal casting type is simple and more affordable compared to the other casting processes. This process uses sand as a mold material. It is usually mixed with a bonding material such as clay. The molds used for this process can withstand high temperatures. During sand casting, a pattern will be submerged in sand inside a special box which is also known as a flask. The sand will be compacted surrounding the pattern, which will create a mold where the liquefied metal will then be poured into. The sand used in the process can be either greensand, which is made of wet clay, or air set sand, which is made of dry sand with an adhesive. 

Casting pressure can be either high or low, which is high pressure die casting and low pressure die casting. The right pressure must be selected according to different factors such as material, part size, and wall thickness. 

High-pressure die casting

This is a more well-known technique than low pressure die casting. It is recommended to use soft alloys like aluminum and zinc. This process is done by forcing the liquefied metal into a mold using high speed and high pressure. It also requires a powerful press to secure the mold and keep it closed while the material solidifies. This process is more expensive than low-pressure die casting. 

What are the advantages of high-pressure die casting?

  • Quick production
  • Can create parts with thin walls
  • Produces parts with a smooth surface finish
  • With least shrinkage

Low-pressure die casting

Low-pressure die casting is a slow form of die casting. This process is slowly done by gently forcing the liquefied metal into the mold. It is recommended for metal alloys that have low melting points. It is appropriate for creating metal parts with complex shapes and sizes. It is known for producing strong and durable metal parts. 

What are the advantages of low-pressure die casting?

  • Produces strong and durable metal parts
  • Creates complex shapes and sizes

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What are the different metals used for metal casting?

Aluminum

Aluminum is one of the most popular nonferrous metals used for casting metal parts. It is used in creating metal parts in different industries. It can be used in manufacturing automotive parts like car engines and transmissions using the metal alloy A380 and A383. 

Aluminum die casting is recommended for the high-volume production of metal parts because it is fast and produces metal parts with an excellent surface finish. To create extra-strength aluminum parts, you can use permanent mold casting, while sand casting is used for casting aluminum in small quantities and creating complex metal parts. Casting aluminum produces strong and lightweight metal parts which make it versatile and useful for different applications. 

Zinc

Zinc alloys are commonly used for metal casting because they are economical and widely available in the market. It uses the high-pressure die casting process which means it is used for the high production of metal parts and requires the least post-processing methods. Zinc has high casting fluidity which means it can produce parts with thin walls and complex details. Zinc alloys have been used to create air conditioning parts, automotive parts, and electronic parts. 

If you are interested to order standard and custom Aluminum and Zinc die-cast products you can rely on SEI Castings. If you want to send a message or an inquiry regarding our products and services please fill up this contact form here. If you want to request a custom die casting quote, please visit this link

We are offering standard and custom die-cast products using non-ferrous metals such as Aluminum and Zinc. We can also provide customized orders according to your specifications. If you are interested in our services and you want to inquire, please email us at sales@seimw.com. Our company address is 66 First Street #4 Gilroy, CA 95020. Call us today! Make sure to choose a trustworthy company like SEI Castings for all your die cast product needs.