Die Casting Case Study: Zinc Die Casting in Automotive Industry

Die casting has become an indispensable manufacturing process in the automotive industry, for which it was originally developed and continues to be used. Although this versatile technology has a wide range of applications in construction and industry, the automotive industry remains its main application area.

The development of modern die casting technology is fundamentally based on the automotive industry's stringent requirements for precision, efficiency and cost-effective mass production.

Why is zinc die casting widely used in the automotive industry?

Zinc die casting is a manufacturing process where molten zinc alloy is injected under high pressure into a precision steel mold. This process is capable of producing parts with complex structures, precise dimensions, high surface finish, and close tolerances, making it ideal for the mass production of complex parts.

Zinc alloys have an excellent strength-to-weight ratio, excellent corrosion resistance, and excellent dimensional stability. These properties give automotive parts sufficient service life and performance, ensuring that the vehicle maintains structural integrity under different temperature and environmental conditions.

Zinc Die Casting Automotive Components

By utilizing zinc alloy materials, manufacturers can mass-produce high-performance auto die casting parts with exceptional dimensional accuracy. Due to zinc's inherent properties, it is also well-suited for electroplating processes. Electroplating not only enhances the corrosion resistance of components but also enables the creation of parts in various colors, such as purple and blue, making automotive components more personalized and distinctive.

Below is a brief list of common Zinc die-cast automotive parts:

• ● Door lock mechanism housing
• ● Seat belt buckle assembly
• ● Wiper motor housing
• ● Window lift gear housing
• ● Interior handle base
• ● Rearview mirror bracket/housing
• ● Shift lever base or bracket
• ● Light bracket
• ● Engine electrical connector housing
• ● Antenna base/mounting base

Zinc alloys advantages

Zinc alloys offer manufacturers the flexibility to manufacture complex geometries while maintaining excellent quality standards and production efficiency. Its high ductility makes it less susceptible to stress and fracture during processing, making it an ideal choice for manufacturing high-quality parts. The advantages of zinc alloys in die casting mainly include:

• ● Low melting point reduces energy consumption by 40-50% during casting
• ● Exceptional fluidity enables production of 0.5mm thin-walled precision components
• ● Achieves dimensional tolerances as tight as ±0.05mm for critical applications
• ● Superior surface finish quality eliminates 80% of secondary machining operations
• ● Natural corrosion resistance provides 20+ years of reliable service life
• ● Excellent plating compatibility allows diverse color and coating customization options
• ● High thermal conductivity ensures efficient heat dissipation in automotive systems
• ● Effective electromagnetic shielding protects sensitive electronic components from interference
• ● Optimal strength-to-weight ratio delivers durability while maintaining lightweight design benefits

Zinc vs Other Materials

Each alloy has unique characteristics, and choosing materials based on the application scenario is a must-have capability for manufacturers. In the die-casting process, there are many metals that are suitable, such as aluminum, cast iron, magnesium, etc. According to the melting point, density, tensile strength and other factors of each alloy, combined with the customer's requirements for the parts, manufacturers need to be very careful in selecting the right material.

The metallic properties of zinc alloys have good electrical conductivity and heat dissipation, making them ideal for automotive applications where thermal management and electrical performance are key factors. Compared with other metal materials, zinc alloys have outstanding corrosion resistance and manufacturability. The surface of zinc metal will naturally form a protective oxide layer to protect it from environmental corrosion.

Zinc Alloys vs Cast Iron

The most significant difference between zinc alloy and cast iron is their processing temperature and dimensional accuracy. Cast iron needs to melt at 1200-1300℃, while zinc alloy melts at only 380-420℃, which reduces energy consumption in the manufacturing process by 60-70%.

Dimensional accuracy is another key difference. Zinc alloys can achieve a tolerance of ±0.05 mm during the casting process, while cast iron usually requires extensive processing to achieve an accuracy of ±0.2 mm. This difference eliminates secondary processing and can reduce production costs by 30-40%.

In automotive parts, one very important parameter is weight. The density of zinc alloy is about 6.6-6.8 g/cm3, while the density of cast iron is 7.2-7.8 g/cm3. The use of zinc alloy can reduce the weight of the corresponding automotive parts by 8-15%.

Zinc Alloys vs Aluminum

Zinc alloy has better dimensional stability than aluminum alloy. The thermal expansion coefficient of aluminum is about 23 × 10⁻⁶/℃, while the common value of zinc alloy is about 26 ~ 30 × 10⁻⁶/℃. In fact, the thermal expansion coefficient of aluminum and zinc is close, not half of that of zinc. However, due to the small internal stress and uniform dimensional shrinkage of zinc alloy during cooling, the overall dimensional stability is still better than that of aluminum alloy. It is especially suitable for parts requiring high precision and can better cope with dimensional changes in high-temperature automotive environments.

Due to the fast cooling rate of aluminum alloy, it is usually difficult to stably cast thin-walled structures below 1.5 mm. Zinc alloy has higher fluidity and a slower cooling rate than aluminum alloy, which can achieve a wall thickness of 0.5 mm or even thinner.

The third point is tensile strength. The density of aluminum is about 2.7 g/cm³. Under the same volume, the weight of aluminum alloy is reduced by an average of 60% compared with zinc alloy. However, in terms of tensile strength, common zinc alloys can reach 280-320 MPa, while aluminum alloy die castings are usually 150-200 MPa, with mechanical properties improved by about 40-60%, making them particularly suitable for small parts with higher strength requirements.

Zinc Alloy vs Magnesium Die Castings

The main difference between zinc and magnesium lies in their reactivity and safety requirements during processing. The high reactivity of magnesium requires a protective gas environment and special safety equipment. Considering processing safety and economy, the die-casting temperature of zinc alloy is low (about 400℃), the process is mature and safe, no additional explosion-proof measures are required, the mold life is longer, and the unit cost is lower. However, due to the high activity and high casting temperature of magnesium alloy (about 650℃), it not only consumes a lot of energy, but also wears the mold quickly and there is a risk of combustion. The overall production safety and cost control are not as stable and reliable as zinc alloy.

Conclusion

We hope this article provides you with valuable information. Die casting plays a vital role in the manufacturing industry. Although it is often regarded as a conventional process, its technical depth and breadth of application cannot be underestimated.

In this sharing, we introduced the advantages of zinc die casting, the differences between zinc and different materials, and also introduced conventional zinc die castings.

Finally, LVMA's die casting services will help you realize your ideas. If you have any needs in product development or mass production, please feel free to contact our engineering team for personalized support and solutions.