An Ultimate Guide to Die Casting

The die casting process produces metal parts with precise geometries and thin walls, making it suitable for high-volume production. This versatile technique produces quality parts well-suited for various industries such as furniture manufacturing, consumer goods, toys, military, and more.

However, some may find the cost of die casting expensive or the method too complex to understand. If you're wondering how die casting works, what materials can be used in this process, or what benefits it brings forth, our ultimate guide on die castings is for you!

We’ll help you understand why this technique is worthy enough to invest your resources in it.

A Brief History of Die Casting

Die casting has a history dating back to the mid-19th century. The first die casting machines were invented in 1838, paving the way for advancements in the industry.

Hot chamber die casting was introduced in 1849, enabling faster production of smaller parts, while cold chamber die casting, patented in 1885, allowed for the production of larger parts and alloys with higher melting points.

Aluminum die casting began in 1914, offering lightweight and corrosion-resistant properties. Zinc die casting gained popularity in 1927, and magnesium die casting emerged in the 1930s.

Post-World War II, die casting saw continuous improvements in materials, technology, and automation. The late 20th century brought computer-aided design and simulation, enhancing precision.

In the 21st century, die casting has become a global industry with applications in automotive and electronics, emphasizing sustainability and efficiency. Ongoing advancements are expected to shape the future of die casting.

How Does Die Casting Work?

Die casting is a metal casting process that involves forcing molten metal into a mold cavity under high pressure. The mold cavity is created using two hardened steel dies, which are machined into the desired shape of the finished product.

Die casting is commonly used to produce complex-shaped parts with high precision and smooth surfaces. Here's an overview of how the die casting process works:

Mold Design

Mold design shapes the final component's geometry. The mold must capture all part details, dimensions, and surface finish requirements.

Designers consider factors like material selection and machine-specific conditions. Attention to detail is crucial due to high pressures during metal injection and cooling, which can impact surface finishes and part deformation if not designed properly.

Metal Preparation

Metal preparation for casting involves carefully managing temperature and composition to prevent defects in the final product. Maintaining the right temperature during injection into the die is crucial, and the metal's composition, including alloy type and purity grade, must meet safety and quality standards.

Quality control measures ensure adherence to industry guidelines, and environmental factors impact cooling times, emphasizing the need for consideration during preheating and post-cooling stages of metallurgical processes.

Clamping

This ensures that molten metal can be injected into a mold. Die casting machines are rated in clamping tons, representing the force they can apply to hold and compress the mold securely.

Special clamping mechanisms, such as toggle linkages, amplify this force and provide a stroke matching the machine's tonnage rating. This combination of mechanical linkage and hydraulic power ensures uniform compression in multiple directions and precise injection of molten metal into the mold with tight tolerances.

Injection

The molten metal, typically aluminum, zinc, or magnesium, is heated to a specific temperature in a furnace.

The die casting machine closes the mold, injecting molten metal into the cavity at high pressure. This pressure is maintained until the casting solidifies.

Cooling

Once the molten metal is injected, it begins to cool and solidify, taking the shape of the mold. The cooling time is critical for achieving the desired properties and avoiding defects.

Ejection

After the metal has solidified, the die casting machine opens the mold, and the newly formed part is ejected from the mold cavity. Ejector pins or mechanisms assist in removing the casting from the dies.

Trimming

The ejected part may have excess material called flash, which is typically removed in a trimming process. Additional finishing processes, such as machining or surface treatments, may be applied to achieve the final product specifications.

Types of Die Casting

Die casting is a process used to produce complex shapes in high-tolerance and widely varied sizes and can be applied to various materials, depending on the use.

The most common types include hot chamber die casting, cold chamber die casting, vacuum die casting, squeeze casting process, semi-solid metal forming, and gravity or low-pressure diecasting.

Hot chamber die casting

The injection mechanism is immersed in a molten metal bath in a hot chamber die casting. The molten metal is automatically drawn into the chamber and then forced into the die cavity under pressure.

This process suits metals with low melting points, such as zinc, tin, and lead.

Cold chamber die casting

Cold chamber die casting is used for metals with higher melting points, such as aluminum, magnesium, and copper.

In this process, the molten metal is ladled into a shot chamber outside the die casting machine. A piston then forces the metal into the die cavity under high pressure. Cold chamber die casting suits a wider range of alloys than hot chamber die casting.

Vacuum die casting

Vacuum die casting is a variation of the traditional die casting process where a vacuum is applied during the die casting cycle.

The purpose is to reduce porosity and improve the quality of the final product by removing gases from the molten metal. This process is often used when producing high-quality parts with stringent requirements.

Squeeze casting process

Squeeze casting combines aspects of both casting and forging processes.

Molten metal is poured into the die cavity, and then a hydraulic press applies additional pressure to the metal during solidification. This results in a more densely packed and finer-grained structure, improving the final product's mechanical properties.

Semi-solid metal forming

Semi-solid metal forming involves the use of partially solidified metal (semi-solid slurry) rather than fully liquid metal. The semi-solid metal is injected into the die cavity under pressure. This process produces parts with high strength and excellent dimensional accuracy.

Gravity or Low-Pressure die casting

Gravity or low-pressure die casting involves the use of a permanent mold and the force of gravity to fill the mold with molten metal. The molten metal is poured into a holding furnace, and then a low-pressure system is used to force the metal into the die. This process is suitable for producing large, complex parts with relatively low pressure.

Pressure die casting

Pressure die casting is a general term encompassing both hot and cold chamber die casting processes.

In both cases, high pressure forces molten metal into a die cavity. This results in fast production cycles and the ability to produce complex and precise parts with high repeatability.

What Materials Can Be Used for Die Casting?

Die-casting involves using a range of high-quality alloys such as aluminum, zinc, copper, magnesium, lead, bronze, and brass to produce detailed metal parts and components with complex geometries and thin walls.

Discover more about the broad spectrum of materials used for die casting and find out how they can be optimally employed for your desired application.

Aluminum alloys

Aluminum is widely used for die casting due to its lightweight, good strength-to-weight ratio, corrosion resistance, and high thermal conductivity. Common aluminum alloys for die casting include A380, A383, and A360.

Zinc alloys

Zinc is another popular choice for die casting, offering good dimensional stability, high impact strength, and excellent corrosion resistance. Common zinc alloys used in die casting include Zamak 3, Zamak 5, and Zamak 7.

Copper alloys

Copper-based alloys, such as brass and bronze, can also be used for die casting. These alloys offer good electrical conductivity, corrosion resistance, and a pleasing appearance. However, they may have higher melting points than aluminum and zinc alloys.

Magnesium alloys

Magnesium is known for its low density, making it the lightest structural metal. Magnesium alloys are used in die casting for applications where weight reduction is critical. Common magnesium alloys include AZ91D and AM60B.

Lead alloys

Lead alloys are less common in die casting due to environmental and health concerns associated with lead. However, lead alloys may still be used for specific applications where their properties, such as softness and malleability, are advantageous.

Bronze and brass alloys

Bronze and brass are copper-based alloys that can be used for die casting. They are valued for their aesthetic qualities, corrosion resistance, and specific mechanical properties. However, they may not be as common as aluminum or zinc alloys in traditional die casting applications.

Advantages of Die Casting

For many industries and applications, die casting is a reliable and efficient choice that yields impressive structural integrity and offers an array of benefits when correctly executed.

These advantages range from quality surface finishes and complex part geometries to high-tolerance production with improved dimensional stability.

Complex shapes

Die casting allows for the production of intricate and complex shapes with high precision. The mold used in the process can be designed to create detailed and sophisticated parts, making it suitable for applications requiring intricate geometries.

Versatility

Die casting can produce a wide range of components, from small, intricate parts to larger, more robust pieces. This versatility makes it applicable across various industries, including automotive, aerospace, electronics, and more.

Cost-saving

Die casting is known for its cost-effectiveness, especially when producing large quantities of parts. The high-speed production capabilities of die casting result in shorter cycle times and lower labor costs compared to other manufacturing processes, contributing to overall cost savings.

Efficiency

The die casting process is highly efficient, with minimal material waste. The molten metal is injected into the die cavity, ensuring the material is used effectively and reducing the need for additional machining or finishing operations. This efficiency translates to a streamlined and resource-effective manufacturing process.

Repeatability

Die casting offers excellent repeatability and consistency in producing parts. Once the die is created, it can be used repeatedly to manufacture identical components, ensuring uniform quality and specifications across large production runs.

Smooth surfaces

Die casting results in parts with smooth surfaces and fine details. The high pressure in the process helps achieve a precise and smooth finish on the final product, reducing the need for additional polishing or finishing steps.

Tensile strength

Die-cast parts exhibit high tensile strength, making them durable and capable of withstanding substantial loads and stresses. This characteristic is particularly beneficial in applications where structural integrity and strength are critical, such as in automotive and aerospace components.

Disadvantages of Die Casting

Porosity

Die casting is prone to porosity issues in the finished product, affecting appearance and durability if not closely monitored during production and post-production activities.

Texture defects

The nature of non-ferrous materials and the die casting process can result in texture defects in the final product, impacting its overall quality.

Inability to be heat treated or stressed in certain ways

Die casted parts may lack the flexibility for heat treatment or specific stress applications, limiting their range of uses.

Complex tooling and precision efforts

Achieving strength with durable components like steel or titanium requires intricate tooling and precision efforts for mold making, restricting the potential applications of die casting.

Residual stresses

Rapid cooling rates during castings can lead to residual stresses within die casted pieces, potentially causing cracks in large pressure die casted items. Additional machining may be required for safe use in a system.

Material restrictions

Due to the operating temperatures of unpressurized chamber machines, die casting is generally limited to materials with melting points below 700°C, such as aluminum.

Limited range of possible items

The combined factors mentioned above restrict the variety of items that can be efficiently produced through die casting processes.

Ongoing optimization efforts

Designers must remain well-versed in optimizing resources to overcome the limitations of die casting, ensuring efficient end products over time.

What Industries Will Need Die Casting?

Die casting is commonly used in several industries beyond conventional automotive parts manufacturing. Many applications require die-cast and machined components for medical equipment, power tools, furniture products, and military defense projects.

Read on to learn more about the applications for each industry:

Automotive Industry

Die casting is extensively used for producing components such as engine blocks, transmission cases, and various automotive parts due to its cost-effectiveness and high production rates.

Electrical Industry

Electrical components like connectors, housings, and heat sinks can be efficiently produced through die casting due to the process's ability to create intricate shapes with good conductivity.

Aerospace Industry

Die casting is employed in the aerospace industry to manufacture lightweight components with high structural integrity, such as aircraft engine parts and structural components.

Medical Industry

Die casting is utilized for medical equipment and devices, including components for diagnostic machines, housings for electronic medical devices, and other precision parts.

Transportation Industry

Beyond automotive, die casting finds applications in the broader transportation sector, including producing components for motorcycles, bicycles, and other vehicles.

Appliance Industry

Die casting is commonly used in the appliance industry to manufacture parts for refrigerators, air conditioners, and other household appliances.

Furniture Industry

While not as prevalent as in some other industries, die casting can be used to produce certain furniture components, such as metal hardware or decorative elements.

It can also be used to produce items such as hinges, knobs, and handles for long-lasting household accessories.

Military Industry

The military uses die casting to produce various components, including weapon parts, communication devices, and other specialized equipment.

Consumer Industry

Die casting is employed for a range of consumer goods, including producing components for cameras, audio equipment, and other electronic devices.

Toys Industry

Die casting is used to manufacture metal parts for certain types of toys, providing a cost-effective method for producing detailed and durable components.

Frequently Asked Questions

In the die casting method, the quality of the product depends on what factors?

In die casting, product quality depends on factors such as material selection, raw material control, process planning, production planning, and die casting machine features.

Material selection influences product strength and durability, with low-melting-point alloys aiding even heating and defect prevention.

Raw material control involves refining to remove impurities ensuring high-quality finished parts. Process planning provides detailed instructions for mass production, reducing variability and downtime.

Production planning considers the required number of parts, setup times, and cycles to meet output requirements without compromising quality. Die casting is an efficient method for the cost-effective manufacturing of metal objects with complex shapes.

Is Die Casting expensive?

Yes, die casting can be costly due to significant upfront expenses for equipment, dies, and related components. For instance, cold chamber die casting machines typically cost between $50,000 and $500,000 or more, depending on size and features.

Additional investments include tooling costs for each unique mold design used in production runs. While these upfront costs may pose a barrier compared to other manufacturing processes, die casting can become cost-effective over time when considering mass production potential and lower tooling costs than alternative methods.

Ultimately, die casting is a worthwhile investment for producing larger quantities of parts or complex shapes that may not easily be achieved through simpler alternatives.

Why Is It Called Die Casting?

Die casting essentially means casting metal into a mold or die. The process produces complex, high-precision parts with a smooth surface finish. The term "die" emphasizes the role of the mold in shaping the final product during the casting process.

Do Die Casting products have a long life?

Yes, die casting typically creates long-lasting products. The lifespan depends on factors like the metal used, production process, and maintenance.

Aluminum alloys last around 100,000 cycles with proper maintenance, while zinc alloys can exceed one million cycles in optimal conditions.

Die casts outperform other components, like machined parts, due to minimal material displacement during production and precise mold design, ensuring lasting accuracy. These qualities lead to significant cost savings compared to alternative methods, such as forging or fabrication processes with multiple components or welding operations.

What Is the Difference Between Die Casting and Forging?

Die casting and forging are metalworking methods that accurately create complex shapes but differ in their approaches and outcomes.

Die casting injects liquid metal into a mold under pressure, producing intricate and precise shapes with advantages like high repeatability, smooth surfaces, and cost savings on aluminum alloys. However, it has limitations on wall thickness and higher costs for zinc alloys.

Forging heats raw materials and applies compressive force to shape them, resulting in wrought parts with improved structural integrity. This process, using presses or hammers, provides better long-term performance and durability than die casting alone.

What kinds of Die Casting Terms do you know?

Die casting is an effective manufacturing process that carefully shapes metals with high-pressure injection molds. Die castings can comprise various materials, including zinc, copper, aluminum, magnesium, and lead alloys.

To ensure consistent quality across production runs — every die cast piece needs to meet certain requirements — various terms are commonly used in die casting industries to define these specific criteria.

Common die casting concepts include tooling for die casting (which designates how molds are arranged), die cast tolerances or dimensional accuracy comparisons (measuring a produced part against its exact dimensions), draught angles (the angle at which walls slope outward within a mould cavity for quicker ejection), and trimming/deburring techniques (to smooth sharp edges after part release).

Concluding Remarks

Die casting is a manufacturing process with numerous advantages - it allows complex shapes to be formed, can produce parts in high volumes at short lead times, and has superior mechanical properties.

It also has some disadvantages, namely the high capital cost of producing die casting equipment or dies/related components; however, proper design for manufacturability can offset this.

Die casting can benefit many industries, such as furniture production, military applications, consumer goods, and toys, where cost savings and manufacturing speed are important factors.

Ultimately, die-casting is beneficial because a strong material product will be produced without any excess labor costs due to the efficient implementation of the relevant processes involved.