Die casting is a manufacturing process that involves injecting molten metal into a mold to produce high-precision and complex parts. This process uses techniques such as high-pressure injection, solidification, and finishing. Skilled operators utilize die casting to create everything from intricate automotive components to sturdy industrial equipment.
Let’s dive into a comprehensive look at die casting, exploring its essential processes, materials, and diverse applications across today’s industrial landscape.
What is Die Casting?
Die casting is a molding process in which molten metal is injected into a mold cavity by pressure and cooled and solidified under pressure to obtain a part. The die casting process has three main components.
- Die casting material
- Die casting Mold
- Die casting machine
What Metal is Used for Die Casting?
Die casting materials include zinc, aluminum, magnesium, copper, tin, lead, etc. Among them, zinc and aluminium alloys are the most widely used, followed by magnesium and copper alloys. We need to choose the right material based on the performance requirements of the part.
Aluminium alloy
It has good casting performance, low density, wide application, excellent thermal conductivity, electrical conductivity, corrosion resistance, and easy machining. Common aluminum alloys include ADC12 (A383), ADC10 (A380), A356, A360, AlSi9Cu3, etc. Aluminium die casting has a wide range of applications.
Zinc alloy
It has high density, low melting point, and good fluidity, and can be used to die-cast complex, thin-walled, and precision parts. Zinc alloys are easier to undergo surface treatments such as welding and electroplating. Common die-cast zinc alloys include:
- Zamak 2
- Zamak 3
- Zamak 5
- ZA-8, etc.
Magnesium Alloy
It has low density, excellent shock absorption and processing properties, and is widely used in mobile phones, communications, medical, and other industries. Common die-cast magnesium alloys include:
- AZ91D
- AM60B
- AM50A
- AS41B, etc.
Copper Alloy
It has a high melting point, good electrical and thermal conductivity, high mechanical properties, easy machining, and relatively high raw material prices. However, the life of copper alloy die casting molds is low, about 2,000 times. Common die casting copper alloys include:
- CuZn25Al5
- CuZn35Al3, etc.
These die casting alloys have different physical and chemical properties, you can choose the right material according to the specific application requirements.
Types of Die Casting
According to the different working principles of die casting machines, we often divide the die casting process into two types:
- Cold Chamber Die casting
- Hot Chamber Die casting
Cold chamber die casting
The cold chamber die casting process is mainly used to cast metals with high melting points, such as aluminium alloys (melting point 660°C), magnesium alloys (649°C), and copper alloys (melting point 1084°C). The metals are melted in a separate crucible and then injected under high pressure into the mold cavity to form the casting.
Hot chamber die casting
The hot chamber die casting process is mainly used to cast some metals with low melting points, such as zinc alloy (melting point 420°C), lead alloy (melting point 327°C), etc. Hot chamber die casting uses less pressure than cold chamber die casting when injecting molten metal, but its work efficiency is higher than cold chamber die casting.
Cold chamber die casting machines complete an average of 80-100 injections per hour, while hot chamber die casting machines complete 400-1000 injections per hour.
What is a Die in Metal Casting?
A die in metal casting is a precision tool that shapes the molten metal into the desired form. It functions as the mold that contains the cavity where the molten metal is injected. Dies are typically made from high-grade steel alloys such as H13 or SKD61, which are selected for their ability to withstand high temperatures and repeated cycles of high-pressure injections.
Dies are designed with multiple parts, including:
- Cavity Blocks: Form the main shape of the casting.
- Cores: Create internal features like holes or undercuts.
- Ejector Pins: Push the solidified part out of the die once it has cooled.
- Cooling Channels: Help regulate the temperature of the die, preventing overheating and extending its lifespan.
Dies are the most critical and expensive component of the die casting process, as they determine the accuracy, surface finish, and overall quality of the cast parts. Proper die design and maintenance are essential for efficient and high-quality production.
What is the Process of Die Casting?
The die casting process involves injecting molten metal into a mold cavity at high pressure, allowing it to cool and solidify to form the final part. Here’s a step-by-step overview of the process:
- Melting: The metal is heated until it becomes molten, either in a furnace or a separate crucible.
- Mold Preparation: The mold is thoroughly cleaned, lubricated, and preheated to ensure optimal performance and to extend its life.
- Pouring and Injection: Molten metal is poured into the die casting machine, which then injects it into the mold cavity at high pressure. This pressure ensures that the metal fills every part of the mold, capturing all details and creating a precise part.
- Cooling and Solidification: The metal cools rapidly within the mould, solidifying into the desired shape.
- Ejection: Once the metal has solidified, the mold is opened, and the casting is ejected using pins or other mechanisms.
- Finishing: The casting may undergo various finishing processes, such as trimming excess material (flash), and surface treatments like polishing, shot blasting, powder coating, or electroplating.
- Inspection: Final inspection ensures that the castings meet quality standards before packaging and shipping.
Die casting is highly efficient and suitable for mass production, making it a preferred choice for manufacturing complex parts with high precision.
Advantages and disadvantages of die casting
| Advantages of Die Casting | Disadvantages of Die casting |
| High Efficiency: Rapid injection, cooling, and solidification significantly shorten the production cycle. | Material Limitations: Die casting is limited to non-ferrous metals like aluminum, zinc, magnesium, and copper alloys; ferrous metals are rarely used due to high melting points. |
| High Flexibility: Capable of producing complex shapes and various sizes, meeting the diverse needs of industries. | Defects in Parts: High pressure and speed can introduce defects such as porosity and shrinkage, although advanced techniques like squeeze casting can help reduce these imperfections. |
| High Precision: Die casting produces parts with tight tolerances and low surface roughness, ideal for intricate designs. | Not Suitable for Small Batches: The high cost of die casting molds makes the process less economical for small production runs, as the cost advantage lies in mass production. |
| High Material Utilization: Defective parts and scrap material can often be recycled, enhancing material efficiency. | High Initial Cost: The setup and tooling costs for die casting are substantial, requiring significant upfront investment, making it less attractive for low-volume projects. |
| Cost-Effective for Mass Production: The cost per unit drops significantly when parts are produced in large volumes. | Not Suitable for Small Batches: The high cost of die casting molds makes the process less economical for small production runs, as the cost advantage lies in mass production. |
Die casting applications
Due to the advantages in the manufacturing process, die casting is widely used in many industries, such as automobiles, electric cars, communication, home appliances, hardware products, power tools, IT, and lighting lamps.
Automotive industry
Die casting can help the automotive industry to realize lightweight, many auto parts are completed by die casting, such as crash beams, doors, gearboxes, cylinder heads, pistons, radiators, motor housings, and so on.
Electric car industry: Electric cars need a die-casting process. Die-casting factories even use 8,000 tons of die-casting machines to cast out the entire body frame. Moreover, batteries, motors, inverters, and other core parts of the shell are completed by die casting.
Communication Industry
Many parts of the communication equipment, such as cell phone shell, router shell, etc., also use die-casting process production. These parts need to be lightweight, beautiful, and have other characteristics, die casting process can realize these requirements.
Household Appliances
In the production of household appliances, the die-casting process is used to manufacture a variety of parts, such as electric fan bases, washing machine bases, etc. Die casting process can provide high precision and high quality parts, and improve the performance and reliability of household appliances.
Lighting Industry
LED lamp shells and radiator parts are also used die die-casting process production. Die casting can realize the demand for high precision and beautiful appearance of these parts.
In addition, die casting is also required in industries such as medical devices and aerospace. Overall, if you want to quickly finish parts with complex shapes, precision, and smooth surfaces, the die-casting process will be a good choice.
Final Thoughts!
Die casting is a highly efficient and precise manufacturing process ideal for producing complex metal parts across various industries, including automotive, electronics, and appliances. It offers significant advantages like high efficiency, flexibility, and cost-effectiveness for mass production.
Despite its limitations, such as material restrictions and high initial costs, die casting remains a valuable choice for creating durable, high-quality components with intricate designs. As industries continue to demand precision and efficiency, die casting will continue to play a key role in modern manufacturing.
FAQs – What is Die Casting?
What is die casting used for?
Die casting is used to manufacture complex, high-precision metal parts for industries such as automotive, electronics, aerospace, household appliances, and more.
What materials are commonly used in die casting?
Common materials used in die casting include aluminium, zinc, magnesium, and copper alloys. Each material is chosen based on its properties like strength, conductivity, and ease of casting.
What are the advantages of die-casting?
Die casting offers several advantages, including high efficiency, the ability to produce complex shapes, excellent dimensional accuracy, smooth surface finishes, and cost-effectiveness for large production runs.
