A Brief Guide to Casting Metals
Are you looking for metal components? The chances are that most of the products you use are casting. But, do you what the process is about? This guide will help you know more about casting, its main features, types of casting, and many more.
Contents
What Is Metal Casting?
Metal casting is a metal fabrication method through which material, mainly molten metal, is introduced into molds and allowed to solidify to take the shape of the mold. After solidification, the part is removed.
Accordingly, casting can be used to describe the final piece produced through different metal casting processes.
Casting is primarily used to produce copies of an original piece. Accordingly, metal casting has been used extensively in various industries, such as automotive, aerospace, and medical, to manufacture various metal parts. When metal casting is done using molten metal, it is called founding. This operation happens in a metal casting foundry.
Types of Metal Casing
Metal casting is primarily divided into two categories, depending on the nature of mold design; expendable mold casting and permanent mold casting. The two categorized can further be divided into different types of casting, as discussed below.
Expendable mold casting
As the name suggests, the expendable mold casting process uses a temporary mold to create final pieces. However, the mold is usually broken in the process of revealing the final product, and it cannot be reused again.
The mold-making process involves the use of sand, ceramic, and plaster materials. These materials are bonded using a binding agent.
Expendable mold casting can be used to produce parts with intricate geometries.
Permanent mold casting
The permanent mold casting process can also be called the non-expendable mold casting process.
This process uses permanent molds to create metal components. Since the molds are permanent, they can be reused in the subsequent production cycles.
Permanent mold casting can produce repeatable parts because the mold is often reused. However, the process is limited in the complexity of parts it can make.
Composite mold casting
Composite mold casting can use both expendable and permanent molds to manufacture castings.
Investment casting
Also known as precision casting or the lost wax casting process, investment casting involves surrounding a pattern with a refractory material. In investment casting, molten metal is poured into a pre-designed mold and left to solidify before the mold is destroyed to reveal the final part.
Investment casting produces metal parts with high dimensional precision, excellent surface finishes, and complex shapes and designs.
The advantages of investment casting include:
- Dimensional accuracy
- High-quality surface finish
- Variety of material selection
- Perfect for intricate parts
Die casting
In the die casting process, the molten metal is poured into the dies under high pressure and speed. This process is mainly used with non-ferrous metal and metal alloys.
Die casting is used for various applications that require small parts with many details and smooth surface finishes.
The advantages of die casting include:
- Perfect for small parts with numerous details
- High accuracy
- It eliminates the need for machining
- Excellent for high production volume
Sand casting
Sand casting is a metal casting process that involves the use of sand as the primary mold-making material. Molds made of sand cannot be reused. However, the material is often relatively affordable, making sand casting a cost-effective metal casting process.
In sand casting, sand is usually mixed with a binding agent, primarily clay. Molten metal is poured into the mold ad left to cool before the mold is destroyed.
The advantages of sand casting include:
- Suitable for producing large metal parts
- Relatively cost-effective
- Wide range of material selection
- Reusable scraps
Lost foam casting
In lost foam casing, manufacturers use expanded polystyrene (EPS)foam patterns. Foam tool creation is often the first stage. Foam pieces are made from the foam tools created. The tool is coated with refractory material and placed in a flask. Sand is then poured around the foam tool after it has dried. This is followed by pouring the molten metal into the flask, burning it, and replacing the foam. After solidification, the part can be subjected to post-processes.
The advantages of lost foam casting include:
- It does not require additives, binders, or cores
- Eliminates wastage
- Highly low cost
- Design flexibility
- Suitable for making complex parts
- Eliminates the need for extensive machining
The Advantages and Disadvantages of Metal Casting
As with all the manufacturing processes, it is essential to understand the basics, pros, and cons to help you make an informed decision. This section looks into the advantages and disadvantages of the metal casting process.
The advantages of metal casting
- Metal casting can be used to manufacture parts with complex specifications.
- With metal casting, manufacturers can achieve features such as cavities and hollow parts.
- Metal casting can use almost all metals to make different parts.
- Casting ensures near-net shape with minimal to no post-processing.
- It can produce large parts.
- Casting helps manufacturers make materials that are more complex and expensive to make using other manufacturing processes.
- Casting is a cost-effective method compared to other manufacturing processes.
Due to these advantages, metal casting is a widely used net shape manufacturing technology. Other methods include forging, additive manufacturing, metal injection molding, and sheet metal stamping.
Disadvantages of metal casting
- The metal casting process, such as shell molding, is limited in terms of the size and pattern of the final product that can be achieved without defects.
- Other processes, such as die casting, can be expensive for low volume production due to the high cost of equipment.
- With metal casting. The part size and material choice depend on the type of casting Other methods, such as permanent mold casting, are only limited to non-ferrous metals.
- Pattern-making can be a very time-consuming and expensive process.
The Bottom Line
Metal casting is a modern manufacturing technology part that comes from the old-age process. In metal casting, metal components are manufactured by pouring molten metal in molds or dies and left to cool/solidify before the mold is destroyed to remove the final part.
Metal casting is one of the ancient and widely used industrial processes in human history. The process is used to manufacture metal components used in every aspect of life. The metal casting applications are wide-ranging from the automotive and aerospace industries to the medical and oil and gas sectors.