Die casting is a versatile manufacturing technique commonly used to create complex metal products. The process is mostly compatible with non-ferrous metals like aluminum, zinc, and magnesium, which do not have iron content. Although non-ferrous metals are common materials used for die casting, ferrous materials like steel and iron are other casting metals with extreme complications. Understanding the different materials used for die casting and their unique properties helps to identify the perfect fit for your project.
This article delves into the importance of material selection and materials used in die casting. By reading to the end, you will also learn about properties influencing die–casting material choice, application, and best practices in selecting the best material for die-casting projects.
The Importance of Material Selection in Die Casting
Die casting is a high-precision manufacturing technique for making complex metal parts with tight tolerances, fine details, and excellent surface finishes. In this process, you have to inject liquid raw material into a mold cavity under high pressure. You must allow the hot, liquid metal to cool and solidify to develop the desired shape.
Die casting works similarly to plastic injection molding but uses metals instead of plastic. Manufacturers produce industrial-grade die-cast parts using real production-grade materials. High-pressure die casting and low-pressure die casting are the typical processes manufacturers use in casting metals into different shapes and sizes. However, to create the perfect die-cast components, it is critical to begin with the selection of the appropriate material for the project.
Selecting suitable casting metals helps ensure the cost-effectiveness of the process, overall quality, and durability of the metal cast. The material used in the die-casting process is essential in determining the project’s success and achieving desired product characteristics.
However, you can choose the best material for the die-casting project by examining the final product’s required durability and strength, preferred surface finish, and material’s thermal and chemical properties.
Key Materials Used in Die Casting
There are different non-ferrous and malleable materials suitable for making metal casts. Each material provides a different combination of properties. We will discuss some of these die-casting materials below:
Aluminum is a primary and highly economical die-casting material with magnesium, copper, and silicon as its constituting elements. Aluminum-based die-casting alloys offer versatile properties well-suited for aerospace, automotive, and consumer goods applications. They exhibit remarkable strength-to-weight ratio, resistance to temperature fluctuations, and high machinability.
The remarkable plasticity of aluminum alloys makes them easily processed into different profiles with good thermal/electrical conductivity and corrosion resistance. Although these alloys are costlier than zin-based alloys, they offer benefits that compensate for the high costs. There is a long list of aluminum alloys compatible with die casting. These include:
- A360: Manufacturers often use this alloy in aluminum die casting due to its excellent pressure tightness and good corrosion resistance. It is most suited for casting parts with high strength and toughness requirements, like transmission cases and engine blocks.
- A380: The aluminum alloy 380 is a multi-purpose aluminum alloy with remarkable dimensional stability, excellent corrosion resistance, strength, and ductility. It is a commonly used aluminum alloy in die casting, suitable for making parts with intricate shapes and thin wall requirements. It is widely used to make engine brackets, gearboxes, power tools, handles, electronic enclosures, etc.
- A413: This alloy is ideal for die casting because of its excellent corrosion resistance and great strength. Die-cast components made with aluminum alloy 413 can withstand harsh environments. This alloy finds use in the marine and automotive industries.
- A443: The aluminum alloy 443 offers the best ductility among the aluminum alloys used in die casting. It is well-suited for making different items for the consumer goods sector. Most notably, components that require plastic deformation after casting.
A significant proportion of die-casting products are made with zinc alloys due to their lower raw material cost. Zinc-based alloys make manufacturing easy because they are compatible with hot chamber die casting. Zinc cast parts exhibit excellent corrosion resistance, which guarantees their longevity.
Zinc’s good thermal conductivity makes it ideal for mass production of die-cast parts. Similarly, zinc alloys provide greater benefits, including excellent ductility, impact strength, hardness, and good plating compatibility. Zinc alloys have various applications, including interior automotive under-the-hood and interior parts. Common zinc die-casting alloys include:
- Zamak 2: This alloy has extra copper content and costs slightly more than other zinc alloys. However, the great strength of this zinc alloy makes it suitable for applications that require metal casts with high strength requirements.
- Zamak 3: It is an all-purpose zinc alloy commonly used in die casting because of its good strength, corrosion resistance, ductility, and dimensional stability. The Zamak 3 alloy is suitable for making parts with intricate specifications like complex shapes and thin walls. Ceiling fans and plumbing parts are typical applications of this zinc alloy.
- Zamak 5: This alloy offers greater strength and hardness than Zamak 3. Hence, it is perfect for making cast parts with higher load-bearing capabilities. Manufacturers often use the Zamak 5 alloy in making parts for the automotive and consumer goods industries.
- ZA-8: It exhibits high strength and remarkable resistance to impact. As such, it is commonly used to cast parts exposed to increased stress and load. Automotive and aerospace applications are typical use of ZA-8.
Magnesium is another key material used in die casting. It comprises aluminum, silicon, manganese, and zinc elements. Not only is it lightweight, it exhibits high machinability and recyclability. Hence, it is perfect for creating products requiring post-processing or surface finishing post-casting. They are also suitable for making parts with exceptionally thin walls.
Magnesium alloys are often used in die-casting operations than aluminum because they are compatible with the hot-chamber die-casting process. These alloys provide high dimensional accuracy and stability and withstand high operating temperatures. However, magnesium alloys require specialized equipment and expertise because casting them into different parts can be challenging. Magnesium-based alloys are less stable and bend easily under stress. Additionally, its high melting point makes it more expensive than other materials used in die casting.
Common magnesium alloys manufacturers use in die casting include:
- AS41B: It is a unique and rare magnesium alloy with high-temperature resistance. It also exhibits remarkable corrosion and creep resistance.
- AM60: This alloy offers good castability, ductility, strength, and vibration dampening. Hence, it is ideal for making automotive parts such as seat frames and panels.
- AZ91D: This is the most widely embraced magnesium die-cast alloy. It offers a distinct combination of mechanical properties, castability, and corrosion resistance.
Copper alloys are suitable for different die-casting applications because they offer excellent corrosion resistance with high strength and hardness. However, their low strength and high-cost factors make them less commonly used materials in die casting.
Since copper alloys are highly susceptible to cracking, they are not often used in die casting as other materials. It creates high thermal shock in the tooling because of its high melt temperature requirement. Standard die-casting copper materials include C17200, C99710, C87500, C99700, C95800, and C99710.
Properties that Influence Material Choice
Although die-casting materials often provide a combination of properties best suited for different applications, these properties often influence the material choice for die-casting projects. The common ones include:
Strength and Durability
Mechanical properties of a material, including strength and durability, are crucial when choosing a material for die-cast parts, especially in applications that demand high-performance parts. This is because these parts must be able to withstand the load and stress they will be subjected to in the intended application.
Similarly, the strength of a material determines its ability to handle the stress and strain it will undergo during the die-casting procedure. Choosing materials with greater strength, such as aluminum, magnesium, and zinc, helps ensure cast parts’ durability and optimal performance.
Melting Point and Fluidity
When choosing materials for die casting, the melting point and fluidity of the material are primary. The melting point of a material for die casting determines the temperature at which it becomes liquid. Fluidity, on the other hand, is the molten metal’s ability to flow and fill the mold’s intricacies without difficulty.
Depending on their composition, materials with relatively low melting points, like zinc, magnesium, and aluminum alloys, are often used for die-casting because they are much easier to process. Besides, magnesium alloys exhibit remarkable fluidity, which makes them suitable for casting parts with complex shapes.
Depending on its intended application, the preferred die-casting material must be corrosion and degradation-resistant. The ability of the material to resist corrosion is a critical consideration when selecting the ideal material for die casting. Aluminum, magnesium, and zinc alloys are typical die-casting materials with outstanding corrosion resistance.
Corrosion influences the quality and durability of die-cast parts over time, causing them to deteriorate. It reduces their strength and durability. As a result, you can ensure the long-lasting performance of your cast parts and prevent potential damage by choosing suitable materials with excellent corrosion resistance properties for your project.
When casting parts for different applications, cost-effectiveness is a primary factor. The cost of the chosen material must fit within the project budget for the material to be suitable for use. Choosing the wrong material can adversely impact the production time, scrap rate, and product lifespan.
For instance, die-casting materials like zinc and aluminum are easy to machine and don’t usually require specialized tools or equipment. Hence, they are cost-effective for high-volume production runs. Due to their unique properties, materials like copper and magnesium are suitable for low-volume production runs. However, they cost more and require skilled experts and specialized equipment, which can influence die casting costs.
Applications of Different Die Casting Materials
Die-casting materials are compatible with various industries and for several applications. These materials are often used for different applications based on their properties. Here are some of the typical applications of die casting in various industries:
Manufacturers often employ materials like zinc or aluminum in automotive die-casting. Materials such as aluminum, magnesium, and zinc offer a combination of desirable properties like lightweight, good impact, and corrosion resistance. Cylinder heads, steering wheels, seat frames, brackets, decorative trim, engine blocks, and transmission cases are typical die-cast products.
Die-casting materials like aluminum and zinc alloys are economical. Hence, they are commonly used in the consumer electronics realm. Similarly, copper offers excellent electrical conductivity, making it well-suited for this application. Other materials, such as magnesium, offer desirable properties such as low weight and good strength-to-weight ratio. Housings for electronics, connectors, buttons, portable electronic devices, heat sinks, and audio equipment are standard die-cast consumer electronic parts.
Manufacturers often use die-casting materials like zinc, magnesium, and aluminum to make different industrial components. These materials offer desired properties such as excellent corrosion resistance, strength, and durability. Typical industrial components produced with die casting include handles, fittings, housing for industrial equipment, machine tools and parts, and industrial connectors.
Product designers and manufacturers in the healthcare sector use the common die-casting materials discussed earlier to produce medical devices like diagnostic equipment and orthopedic devices. Magnesium alloys are biocompatible and offer good strength, making them suitable for braces, prosthetics, and orthopedic implants. Aluminum and zinc alloys offer good mechanical properties and corrosion resistance, making them perfect casting metals for medical applications.
Best Practices in Material Selection
When die-casting parts, there are practical tips to consider in selecting the suitable material for your project. Here are some of these best practices:
Analyzing Application Requirements
Ensure that you analyze the application requirements of your die-casting products when selecting the appropriate material for your die-cast project. It would be best to consider variables such as heat and corrosion resistance, surface finish, strength, and durability.
Identify if the part will be subjected to high temperature, harsh chemicals, or environment. Due to their excellent thermal conductivity, zinc or copper are suitable for producing parts that can withstand high heat. On the other hand, zinc or aluminum may be the perfect casting metals for applications that require die-cast parts that can withstand corrosive elements or environments.
Manufacturers commonly use aluminum for applications that require specific finishes or textures since aluminum alloys are highly machinable and offer excellent surface finishes. Nevertheless, zinc or copper is the best option if your parts will bear high stress or load.
Considering Environmental Factors
Environmental factors are vital in the material selection for die-casting projects. Die-casting materials such as zinc and aluminum exhibit high recyclability. Hence, they reduce the environmental footprint and promote sustainability. This attribute makes them more suitable options than magnesium and copper, which offer limited recyclability.
In addition, ensure that the preferred material for die casting meets the RoHS (Restriction of Hazardous Substances) regulations when making electronic and electrical parts.
Long-Term Performance Criteria
Examining the long-term performance criteria of an intended material for die-casting is essential to ensure the longevity and proper functioning of die-cast parts. To make parts that can withstand wear and friction, choose materials that offer excellent wear resistance, like aluminum alloy 390.
Magnesium alloys are the perfect choice if you need parts that can resist deformation over time. These alloys offer excellent resistance to creep, making them best suited for applications with prolonged stress. Similarly, consider the expected fatigue life requirement of the intended product to choose the suitable material. If the intended application involves cyclic loading, using material that offers good fatigue strength, like aluminum and zinc alloys would be best.
Selecting the right material for your die-casting project can significantly impact the tooling costs, repeatability of the process, and part’s durability. Since there are various materials for die casting processes, it is crucial to understand available materials for die casting and their properties to choose the best material for die casting. This guide has provided a detailed discussion on materials for die casting to guide you through the selection process.
However, you can contact Zintilon whenever you need the help of an expert in the material selection phase of your die-casting project. We offer professional die-casting services that help you achieve optimal benefits from die-casting processes.
As a manufacturing expert with extensive experience, we ensure a quick lead time for precise and superior-quality die-cast parts. Contact us today if you have a new project in mind; we offer instant quotes. Our goal is to deliver a satisfactory manufacturing experience!
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