What Is Casting Parts in Manufacturing?

Have you ever wondered what’s one of the oldest manufacturing methods? The answer is casting. In fact, it’s so old that it dates back thousands of years. Yet, casting parts is still a popular method used to create parts. But why is that and what is casting?

Casting is a manufacturing process that involves pouring molten metal - or other materials - into a mold to form a desired shape. As the molten material cools and solidifies, it takes the shape of the mold. The end result? Complex parts that require minimal machining.

But what are the 4 types of metal casting & in what scenarios should you use it? We’ll answer all these questions - and more - in this article.

What Is Meant by Casting Manufacturing Process?

Casting process in manufacturing refers to pouring molten materials into a mold. These materials range from metal, plastic, glass to ceramic and others. The molten material is then left to cool, after which it solidifies into the desired shape.

The actual way it’s done depends on the chosen casting method. However, generally they follow a series of steps, including:

1. Mold Preparation

First, the mold used in the casting process is created, and its either:

1. Single-use molds (meaning they’re destroyed after each use).
2. Reusable molds (used multiple times, typically in larger production runs).

These molds are made from materials like sand, ceramic, plaster, or metal, depending on the casting method. The mold will essentially dictate the shape of the final product.

2. Melting and Pouring the Material

The selected material is melted in a furnace to reach the required temperature for pouring. During this process, fluxes or degassing techniques remove impurities from the molten material.

It’s then carefully poured into the mold cavity using multiple methods, depending on the chosen casting type.

3. Cooling and Solidification

The molten material cools and solidifies at a controlled rate. The rate of which it cools down will determine the mechanical properties and strengths of the final component. There are two primary cooling rates:

• Fast cooling (creates fine-grained structures and improves the strength).
• Slow cooling (helps to create better stress relief but may require post-processing).

 

4. Removing the Cast Part from the Mold and Cleaning/Finishing

The mold is removed/broken away once the material has solidified. After this stage, the raw cast part may have excess materials and surface imperfections. It then undergoes a cleaning and finishing stage to remove excess material and refine the surface. These steps may include:

• Trimming
• Grinding
• Abrasive blasting
• Other surface treatments

 

What Types of Materials Can Be Cast?

While the casting process seems straightforward. It’s important to keep in mind the choice of casting material is key. Not only will it directly influence the mechanical properties and durability of the final product. But it also affects its suitability for specific applications.

As a result, there’s often a balance between cost and quality when selecting materials. So let’s take a look at the most common materials used in casting.

1. Metals

One of the common cast materials is metals such as steel, iron, aluminium, copper alloys and zink. While these materials have their own strengths and weaknesses. Metals are usually chosen due to their strengths, durability and versatility.

2. Alloys

An alloy is a mixture of a metal with one or more other elements. These could be metals or non-metals. The reason for blending elements is that it alters the metal structure and can improve its properties. For example, its strength, corrosion resistance, and castability. As a result, alloys often provide better mechanical performance, durability, and manufacturability.

3. Non-Metallic Materials

In certain cases it’s important that the casting material offers properties like weight reduction, chemical resistance, or cost efficiency. It is in these scenarios that many companies turn to what's called “non-metallic” materials. These include:

• Plastics
• Ceramics
• Glass
• Composites

Non-metallic materials are naturally corrosion-resistant, non-conductive, and more cost-effective to produce. That’s why they’re especially advantageous for high-volume production.

What Are the Four Main Types of Metal Casting Methods?

There are different types of casting techniques. Each has its own pros and cons depending on the application and materials required. We’ll go through the 4 main types of casting methods below:

1. Sand Casting

Sand casting is the oldest metal casting method. As the name implies, it uses sand mixed with a binding agent to form a mold. The molten metal is then poured into this sand mold, where it cools and solidifies. Finally, the mold is broken away to retrieve the cast part.

The final casting often has a rougher surface texture. As such, it usually requires cleaning, machining, or finishing to meet precise specifications.

• Advantages: Works with almost any metal, cost-effective for low-volume production, and suitable for large and heavy parts.
• Challenges: Requires post-processing to improve surface finish, and mold reusability is limited.

 

2. Die Casting

Die casting is one of the most widely used metal casting processes. But it’s very different from other casting techniques that rely on gravity or manual pouring. Because die casting forces molten metal into a precisely machined steel mold (known as a die) under extremely high pressure.

The injection is controlled to ensure the molten metal fills the entire mold. Hence, it’s able to produce complex parts with tighter tolerances, smoother surfaces and greater dimensional accuracy.

• Advantages: High-speed production, excellent dimensional accuracy, and minimal finishing required.
• Challenges: High initial tooling cost, best suited for high-volume production.

 

3. Investment Casting (Lost Wax Casting)

The third casting method is a precision casting process called “investment casting”. This casting begins with the creation of a wax model that replicates the final part. This wax model is then coated with multiple layers of ceramic slurry to form a durable mold. Once its shell hardens, the wax is melted and drained away. Leaving behind a hollow cavity in the exact shape of the desired component.

Molten metal is then poured into the cavity. After the metal cools and solidifies, the ceramic shell is broken away to reveal the finished casting.

• Advantages: Can produce fine details and thin walls, minimises machining, and provides greater surface finish.
• Challenges: More expensive than other methods, longer production cycle.

4. Permanent Mold Casting

Permanent mold casting is relatively similar to die casting. But instead of using high pressure to inject the molten metal, it uses gravity or vacuum assistance. The metal cools and solidifies within the mold. Once set, the casting is removed and the mold can be reused for subsequent production cycles.

• Advantages: Produces stronger parts with better mechanical properties than sand casting, reusable molds reduce waste.
• Challenges: Limited to non-ferrous metals like aluminum and magnesium. The mold fabrication can be expensive.

 

Frequently Asked Questions

What Is the Difference Between Casting and Forging Parts?

In casting, molten metal is poured into a mold. Whereas forging uses high-pressure force on heated metal. Casting is ideal for complex shapes and designs, whereas forging is better for high-strength applications.

Conclusion: What Is Casting Parts?

In this article we clarified what casting parts are. Essentially casting is a manufacturing process that involves pouring molten metal or other materials into a mold to form a desired shape. And in this scenario into a part.

Now which material is used for the mold, the process in which it takes place, will vary greatly depending on which of the 4 types of casting processes you use. Each has its own pros and cons, making it a matter of balancing cost and quality.

One of the key challenges when you’re looking to cast parts is the capability and pricing can vary greatly depending on the foundries. Haizol connects you with thousands of trusted metal casting suppliers across Asia. Submit a free request for quotation today to receive multiple quotes from trusted suppliers within the same day.