Introduction

Zinc die casting involves heating zinc pieces into molten form before allowing them to solidify to the desired shape. The metal possesses good mechanical and physical properties, making it suitable for various manufacturing purposes. Zinc is a non-ferrous metal that has a relatively low melting point, making it a good candidate for this technique. 

Die casting
Die casting

This article discusses all you need to understand about die casting zinc parts for your manufacturing needs. Read ahead!

What is Zinc Die Casting?

Zinc die casting is a involves heating zinc alloys into molten form and forcing them into a pre-made die casting mold, where they solidify. It is called zinc die casting because it is a type of die casting specific for zinc alloys.

The process is highly efficient and versatile, suitable for fabricating intricate and complex zinc parts with high precision. Zinc alloys are ideal for this process because of their excellent mechanical properties, especially its low melting point. Also, it has good conductivity, ductility, and strength, making it suitable for fabricating challenging parts that require durability as a criterion.

In addition, because of the relatively low melting point of zinc alloys, zinc die casting usually follows the hot chamber die casting process. However, this feature benefits die casting, increasing the die mold’s longevity and reducing production cycle times.

Stepwise Guide for Zinc Die Casting Process

As mentioned above, zinc die casting follows the hot chamber die casting process. However, even the cold chamber process is suitable. Regardless, die casting follows a similar mechanism. Below is a summary of the manufacturing process.

Step 1: Mold Preparation

The process starts with creating the die casting mold, which will have the desired component’s intended shape and geometrical features. The die cast mold is usually made of aluminum or steel. 

Afterward, still under mold preparation is the cleaning of the mold to remove impurities. Then, lubricating of the mold for easier ejection of die cast parts after casting. The end of mold preparation is clamping it under high pressure.

Step 2: Melting and Injection of Zinc Alloy

Melt blocks of zinc (often > 400°C or 800° F) and pour into the shot chamber. Then, proceed to inject the liquefied zinc material into the mold under high pressure, ensuring it fills the mold so that it can produce all the details of the mold.

Step 3: Cooling and Ejection

Afterward, allow the molten zinc to cool down and solidify in the die-cast mold, where it takes the precise shape and features of the mold. The next step is to unclamp the mold to allow the ejection of the newly formed solid zinc casting out of the die.

Step 4: Trimming and Finishing 

After ejecting the solidified die castings, some excesses usually require trimming and some secondary finishing to improve the appearance. You can cut the excesses with a trim die or saw and proceed to other finishes, like surface treatments and coating options, to enhance the part’s aesthetics.

Standard Zinc Alloys for Zinc Die Casting 

Several zinc alloys are suitable for die casting because of their relatively low melting point. Moreover, it has good dimensional stability; even after heating to molten form and resolidification, it retains most of its physical and mechanical properties. 

Below, we explore some of the most used zinc alloys for die casting parts.

Zamak 2

Zamak 2, also called zinc alloy 2, consists of various alloying elements, predominantly aluminum, magnesium, and copper. It is known for its excellent strength, the strongest and most rigid zinc alloy among the Zamaks.

However, it has good casting properties, maintaining its structural integrity and strength even after casting. Consequently, it is suitable for fabricating intricate shapes and high-strength components for the mechanical and automotive industries.

Zamak 3

Zamak 3, or Zinc Alloy 3, is an excellent die casting alloy because of its incredible strength, ductility, and castability. The composition of this alloy is similar to Zamak 2. However, its mechanical features are more balanced, making it a better option for versatility. Zamak 3 also showcases compatibility with different surface finishes such as plating, painting, and chromate treatments.

Zamak 5

Zamak 5 (zinc alloy 5) has a higher copper content than Zamak 3, causing it to have higher strength and hardness, though it is less ductile. This feature makes it a good choice for components that require high mechanical properties. However, because of its lesser ductility, it may reduce its formability.

Zamak  7

Zamak 7, zinc alloy 7, is a variant of Zamak 3, but slightly modified. It has lower amounts of magnesium and impurities than other Zamak alloys. However, this accounts for its improved castability, flexibility, dimensional stability, and surface finishing. Therefore, it is essential for fabricating intricate and delicate parts and thin-walled components.

ZA 8

ZA-8, as the name suggests, is essentially a mixture of zinc and aluminum, though zinc is still the base material. Therefore, compared to the Zamak family, it contains high amounts of aluminum. However, it also contains copper and magnesium in smaller amounts. The alloy has considerable strength and hardness, making it suitable for parts requiring durability as a prominent feature.

ACuZinc5

ACuZinc5 is known for its good balance of strength, castability, hardness, lubricity, and creep resistance. The zinc alloy features aluminum and copper, with traces of magnesium, resulting in a zinc alloy with improved corrosion resistance. Therefore, it is highly durable and suitable for parts requiring high structural integrity and harsh environments.

EZAC

Even though it contains significant amounts of aluminum, like ZA 8, zinc alloy EZAC is also compatible with hot chamber die casting because of its reduced melting point. It has good creep resistance, high fluidity and hardness, castability, and tensile strength. The alloy is suitable for fabricating intricate parts and thin-walled components.

Block of zinc alloys
Block of zinc alloys

ZA 27 

As the name suggests, the zinc alloy ZA 27 contains about 27% aluminum, making it lightweight, yet retaining its strength and durability. The high amounts of aluminum help to increase the alloy’s applications and durability. ZA 27 suits vast applications, including delicate components demanding high structural integrity.

Why Use Zinc for Die Casting Parts?

Zinc has reasonable physical, mechanical, and chemical properties that make it suitable for die casting parts. Below is a list of some features that make zinc alloy a good candidate for this manufacturing technique.

  • Efficient thermal conductivity and dissipation: Zinc is a good conductor and supports easy dissipation of heat. This feature is particularly vital for die casting parts.
  • High precision and dimensional stability: Zinc can create parts with tight tolerance specifications and retains high dimensional stability even upon exposure to harsh conditions.
  • Impeccable strength, corrosion resistance, and durability: Some of the good mechanical properties of zinc include its high tensile strength, corrosion resistance, and hardness, making it suitable for highly durable fabrications and parts exposed to harsh environments.
  • Exceptional fluidity and formability, even after heating to the molten state: The high fluidity of molten zinc makes it suitable for fabricating intricate designs.
  • Cost-effectiveness: While die casting is relatively cheaper than other manufacturing processes, zinc uses the hot chamber die casting process, which is even more affordable than other types of die casting. Therefore, zinc die casting is cost-effective, especially for bulk volume production.

Benefits of Zinc Die Casting

Zinc die casting is versatile, with various advantages, because of the metal’s mechanical properties. Below, we explore some of the benefits of this operation for manufacturing zinc parts.

Low Tooling Costs

One of the common advantages of die casting is its cost-effectiveness. The tooling costs for zinc die casting is relatively low, especially compared to similar manufacturing processes. This advantage makes the method popular for projects on a strict budget.

High Precision and Dimensional Accuracy 

Fabricating zinc parts with die casting is a high-precision and accurate process. While the operation is not as precise as manufacturing methods, like CNC machining, it yields parts with an accuracy of up to 0.1 millimeters for the first 2.5 centimers and 0.02 millimeters for subsequent centimeters.

In fact, zinc, because of its strength compared to other die casting alloys, is suitable for fabricating parts with tight tolerance specifications, such as thin wall components.

Enhanced Mechanical Features

As suggested earlier, zinc is stronger and more durable than other metals, like aluminum. Therefore, fabricating parts with zinc alloys helps to yield die-casting parts with enhanced mechanical properties. Moreover, zinc also possesses significant resistance to corrosion, increasing its durability. Therefore, it is suitable for manufacturing components exposed to harsh environments and mechanical stress.

Quick and Efficient Zinc Parts Fabrication

Zinc’s low melting point ensures it quickly melts upon heating, increasing the production cycle time. In fact, its reduced melting point compared to aluminum and magnesium makes it a good candidate for hot chamber die casting, further increasing the production rates and efficiency.

Long-lasting Tool Lifespan 

Since zinc has lower melting points, the die casting molds do not experience excessively high melting temperatures. Therefore, there is less risk of mold damage, prolonging tool life. Moreover, zinc metal is less abrasive and has other favorable properties. This characteristic also enhances the cost-effectiveness and part quality over extended production cycles.

Suitable for Complex Geometries

In the molten state, zinc shows good fluid properties, making it a zinc die casting popular choice for creating parts with complex geometries and intricate designs. Therefore, the process is vital for components with intricate shapes and features integral to the product design.

Shortcomings of Zinc Die Casting

While zinc die casting offers several benefits, this process has some shortcomings. Below are some.

Unsuitable for Low-volume Production

Zinc die casting is preferred for mass production because of its high initial investment. The initial tooling and machine set-up costs are relatively low, so they are unadvised for low-volume production. Instead, you should partner with a service provider for such purposes. 

Likely to Experience Casting Defects

Even though it’s a high-precision manufacturing method, it’s still susceptible to certain die casting defects. Some of which are associated with the high filling speed and rapid cooling. Typical flaws include gas porosity and cold shuts. If care is not taken during fabrication, these defects will diminish the quality of the finished product.

Unsuitable for Creating Lightweight Parts 

Zinc is a relatively high-density metal, especially in comparison to aluminum. Therefore, it generally yields heavy parts. This feature reduces its effectiveness for manufacturing parts with strict lightweight specifications, such as in the aerospace industry and in manufacturing some automotive components.

Applications of Zinc Die Cast Parts

Zinc die-cast parts are suitable for various industrial applications. Let’s look straight into some of the uses of die-cast parts. 

Automotive Industry

Zinc die-casts are suitable for creating various parts for the automotive industry, especially the interior components. Compared to materials like aluminum, zinc is stronger, making it valuable for car parts such as steering, bearings, brakes, and transmission.

Medical Equipment and Gadgets

Zinc die casting parts are suitable for creating medical gadgets, including diagnostic tools and handles of medical devices. The process is precise and supports dimensional accuracy, making it ideal for producing parts for the medical industry.

Electronics

Zinc alloy die casting is ideal for making components for the electronic industry. These include toggle switches, clocks, energy regulators, connectors, etc. That said, zamak 3 zinc alloy is the most appropriate for making electronic parts. This is because of its dimensional stability and good electrical conductive properties.

Household Appliances 

Zinc die casting parts are suitable for making household appliances like coffee makers, vacuum cleaners, furniture inserts, blenders, key chains, and door locks and handles. The strength of zinc makes it suitable for creating home appliances. 

Customized Zinc Die-Casting Parts 

Because of zinc’s ability to adapt to various applications, it is suitable for customization. Its high strength and dimensional stability make it an excellent choice for custom die casting parts. Also, the casting process is cost-effective, further reinforcing its choice for fabricating custom parts and producing prototypes for testing a design before full-scale production.

Products of zinc die castings
Products of zinc die castings

Finishing and Post-processing Options for Zinc Die Casting Parts 

While zinc die casting yields parts with good precision and a decent aesthetic, applying finishing to your parts helps to improve the appearance and mechanical properties. Below are a series of standard finishing and post-processing options for your zinc die-cast parts. 

Painting

Painting refers to applying liquid paints or lacquers over a surface to improve its appearance. The finish allows different coloring to enhance the aesthetics of zinc die castings. Also, it improves the corrosion resistance and durability of the components. 

Polishing

Polishing involves robbing an abrasive material over the surface of a metal surface, ridding imperfections and blemishes. The finish helps improve the smoothness and consistency of the zinc die cast, improving the overall surface property and aesthetics.

Powder Coating

Like painting, powder coating coats the surface of the zinc die cast components, though it involves using a dry powder. Also, it offers an extensive range of color options, improving the visual appearance. Besides aesthetics, it also enhances corrosion and overall chemical resistance. 

Electroplating

Electroplating is another surface finish that involves coating the metal surface. However, this involves depositing a thin metal layer to cover the zinc die cast parts. The finish enhances the part’s corrosion resistance, conductivity, and overall mechanical features. Besides, it also improves the appearance and aesthetics of the part.

Anodizing 

Like electroplating, anodizing is an electrochemical process. However, instead of coating with another metal, anodizing coats with the metal oxides. Therefore, in the case of zinc die cast components, anodizing involves forming a protective layer of zinc oxide to shield the metal. The finish improves aesthetics, including mechanical and chemical resistance. 

Zintilon’s Expert Zinc Die Casting  Services 

While understanding the intricacies of zinc die casting is vital before using it for your project, partnering with a service will save you lots of hassle, especially die casting defects. Zintilon is an expert die casting service provider, ensuring that your fabrication attains your desired specification.

Our die casting services are of industry standard, which suggests that you can rely on our products. We boast highly skilled engineers who know the best way to go about your fabrication. That said, we also offer expert services in CNC machining, rapid prototyping, sheet metal fabrication, and other related technologies.

Contact us today!

Conclusion

Zinc has some excellent mechanical properties, including good thermal conductivity and heat dissipation, high tensile strength, corrosion resistance, and fluidity. All these features make the metal a good choice for die-cast parts. 

Die casting zinc is an integral part of manufacturing parts for various industries. The process suits vast applications, including the automotive and medical industries, where precision is a significant criterion. However, because of the metal’s high density, it is not a popular choice in the aerospace industry.

FAQs

Can Zinc Die-Cast Rust?

Generally, zinc die cast is corrosion resistant; it does not rust. Zinc exposure to atmospheric conditions forms a protective oxide – zinc oxide – which prevents metal corrosion. However, zinc may lose its corrosion resistance if this protective oxide gets compromised.

Why is Zinc Used for Die Casting?

Zinc is used in die casting because of its suitable mechanical and chemical properties. The metal has excellent fluidity in its molten state, making it ideal for fabricating intricate and complex structures. Moreover, it is dimensionally stable, making it a good metal choice for vast applications, including parts with strict tolerance and precision requirements. 

How Strong is Zinc Die Cast?

Zinc die-cast parts possess considerable strength, one of the main properties of zinc metal. Moreover, the alloys used in die casting usually contain other alloying metals like aluminum, copper, and magnesium, which help improve their strength and other mechanical features.

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