The process of zinc casting is used to manufacture durable parts with exactitude. Manufacturers melt zinc at its melting temperature and charge it into molds. The mold contains the product shape. It falls under any industry like automotive, industrial, or electronics. Basically, this process is ideal for getting highly complex parts with less effort.

This article defines what zinc casting is, including its different alloys and their uses. Discover this casting technique’s special uses, benefits, and drawbacks.

What is Zinc Casting?

Zinc casting is a manufacturing process. It makes parts with tight tolerances. That can be as small as 0.1 mm. The key steps are melting zinc and pouring it into the die under high pressure (1,500 to 2,500 psi). At this point, the liquid is converted into an actual shape.

Zinc Casting Alloys

The combination of zinc and other metals forms variant zinc alloys. These are extremely important to make distinctively shaped parts that support each industry. The addition of other elements causes the alloys to reduce their melting temperatures (around 385°C). They are also lighter in weight, with a density of 6.6 g/cm³.

ZAMAK 2:

There are 4% aluminum, 3% copper, and 0.1% magnesium in the Zamak 2 alloy. This composite brings a tensile strength of around 359 MPa. The parts made with this alloy have a hardness of 91 Brinell.

This is why it suits wear-resistant parts like locks or gears.

It melts at 385°C. Speaking of its cost, it can be higher by about 15% as there is more copper added.

ZAMAK 3:

Zamak 3 contains 96% zinc, 4% aluminum, and 0.04% magnesium. It, being a common alloy, gives 283 MPa tensile strength and 82 Brinell hardness. This alloy creates very smooth surfaces with less roughness (1.6 µm roughness).

You can cast them easily. They manufacture several parts, like door handles, electrical connectors, and consumer goods, because of their affordability.

ZAMAK 5:

Zamak 5 has 1% copper and the remaining elements of Zamak 3. This means the tensile strength of this alloy reaches 328 MPA. It has successfully resisted 50,000+ cycles in gears or industrial setups. Also, the alloy melts early to 387°C and resists the effect of corrosion better than Zamak 3 as well.

ZA-8:

ZA-8 includes 8.4% aluminum, 1% copper, and a small amount of magnesium (0.02%). It manages temperatures up to 120 °C. Its tensile strength ranges from 374 MPa. You can use this alloy in engine housings and high-stress or high-temperature electrical assemblies.

ACuZinc5:

ACuZinc5 is an alloy that contains 5% more copper and 5% aluminum. It has a tensile strength of 440 MPa. Copper addition raises its hardness. That reaches around 120 Brinell. This alloy suits parts needing wear resistance. For instance, heavy-duty bearings or hydraulic.

EZAC (European Zinc-Aluminum-Copper):

This alloy has less copper, around 0.5%, but contains 2% aluminum, so the tensile strength ranges from 310 MPa. You can use it for eco-friendly parts. This is because it can survive 1,000 hours of salt spray, however, depending on coatings and test requirements. This test occurs for marine hardware.

ZA-12:

There is 12% aluminum plus 0.6% copper content. It has a tensile force of 400 MPa. The Brinell hardness ranges 110. This suits structural components such as the brackets in trucks or construction items.

GDSL (Guss Druck Sonderlegierung):

It is a German specialty alloy. There is a 1.5% nickel, and the titanium is around 0.5%. They handle high temperatures ranging from 150°C. Aerospace sensors and pressure medical requirements are made with it to get ±0.05 mm tolerances.

The Zinc Casting Process

Mold Creation and Design:

According to the final parts, the designs shape the mold with cavities and use steel metals. Casting needs proper temperatures and, therefore, places cooling channels to control them.

An interesting fact is that a designed mold (die) can handle massive production of up to 500,000 parts before needing replacement.

Melting and Zinc Injection Molding:

The metal workers melt zinc alloys at their melting temperature. This molten liquid then transfers toward the die. They pour it into it under high pressure within 0.1 seconds.

Cooling and Solidification:

The cooling process aids in lowering the die temperature to 150 °C. The cooling channels solidify zinc, usually taking 5 to 10 seconds. They also resist various defects, like air pockets.

Ejection and Finishing:

Ejector pins use 10 to 20 tons of force, which works for pushing out solidified parts. The ejected parts need excess material to be trimmed off, so cut up to 2 mm edges. Also, you need to apply coatings to protect their base and get smooth finishes.

Role of Zinc Die Casting Machines:

The casting outcome depends entirely on the selected alloy and machines. The machines usually use hydraulics to handle injection speed and pressure. In particular, modern machines work smartly and can complete each cycle in no more than 30 seconds.

Importance of Precision and Tight Tolerances:

When you make parts with zinc die casting, it achieves tolerances of ±0.1 mm, getting perfect fits to assemble various parts. Because these snap-fit parts are needed for electronics, car engines, and medical gadgets.

Properties of Zinc Alloys

Zinc alloys give good castability as they have high fluidity. This is why they fill complex design parts, taking less effort. Also, they melt at lower temperatures, meaning less usage of energy and extending mold life.

Each alloy possesses different properties in regard to corrosion resistance, tensile strength, hardness, etc., as the table shows.

Zinc vs. Aluminum, Magnesium, Steel:

• Zinc vs. Aluminum: Zinc is 40% denser (6.6 g/cm³ vs. 2.7 g/cm³). It is, however, much easier to work with and can take on sharper details.
• Zinc vs. Magnesium: Zinc resists the effect of corrosion generally better. It is also 20% cheaper per ton.
• Zinc vs. Steel: The zinc weight is less, around 15% (6.6 g/cm³ vs. 7.8 g/cm³). It needs less energy (60%) to melt.

Advantages of Zinc Casting

Cost-Effectiveness and Production Efficiency

The affordability of zinc casting is one of its biggest advantages. This is because they melt at lower temperatures. That’s means less energy is needed.

Another reason includes its single mold capability. That can handle large production and results in less tooling cost. Similarly, machines can make 200 parts in one hour, which therefore lessens labor costs.

Excellent Surface Finish and Design Flexibility

Zinc casting produces parts with fine quality and smooth surfaces. They eliminate the need to apply additional coatings for finishing.

Also, they are able to give enough space for designing logos, textures, or angles as small as 0.5 mm. That, as a result, defines aesthetic needs.

Ability to Produce Complex Shapes and Thin Walls

Even with complex shapes, zinc casting can add specific details, such as the gears with 12+ teeth. It also produces parts with thinner walls, as minimum as 0.8 mm.

This means there is a need for only fewer assembly steps. So the overall production time is also reduced by 30%.

Recyclability and Environmental Benefits

You can reuse zinc, as it is recyclable at 95% and does not lose its quality. Recycling techniques also need 30% less energy as compared to raw materials. It’s an environmentally friendly metal.

High-Volume Production Capabilities

Zinc die casting suits larger production. Which alternatively reduces per-unit cost. Also, the tooling equipment and machines last longer.

Applications of Zinc Casting

Automotive Industry

Zinc casting extends bracket durability up to 200,000 km. Also, it creates fuel injectors with tight tolerances and even temperature-resistant (120°C) transmission housings.

The parts like door handles and mirror housings made with zinc casting stand up against harsh weather and do not corrode.

Electronics Industry

There are many items that are produced via the zinc casting process. They include connectors with 16.6 MS/m electrical conductivity, heat sinks (113 W/m·K thermal conductivity), and the battery case.

These parts, like the protective shield. This is because they protect parts from electromagnetic inference. They also handle 10,000 plug-in cycles.

Consumer Products

Zippers with 1 million+ cycles, locks with 0.5 mm accuracy pins, door handles supporting 50 kg force, and decorating products are the zinc casting consumer applications.

Industrial Equipment

Zin die casting makes gears and pump housings that resist up to 500 hours of salt spray. Also, the valve bodies with the management of 2000 psi pressures and several custom parts like conveyor belt rollers use this process.

Emerging Applications

Renewable energy uses zinc casting for manufacturing solar panel frames and wind turbine sensors. Speaking of the medical sector, it produces surgical tool housing and MRI machining components.

Custom Parts and Prototyping

You can use zinc casting to make complex shapes of prototypes in no more than 2 weeks. This is because of the flexibility of this process. Meanwhile, the custom automotive prototype reduces development costs (40%) compared to steel.

Zinc Casting vs. Other Manufacturing MethodZinc vs. Aluminum Die Casting

Aluminum melts at 660 °C, which means it needs more energy than zinc alloys. Zinc alloy molds last longer, while aluminum ones can wear out after 300,000 cycles. The zinc parts contain 280 MPa strength, but aluminum gets 220 Mpa depending on its grade.

Aluminum components, however, are 60% lighter. Zinc casting goes well with manufacturing small-size parts, but aluminum can create larger sizes like engine blocks.

Zinc vs. Magnesium Die Casting

Zinc is cheaper than magnesium, which costs 25% more per ton. Magnesium is not heavier than zinc; it is  30% less. Also, the zinc can survive the salt spray test 5x longer.

The aerospace industry chooses magnesium because of its lightweight feature. Meanwhile,  zinc mostly produces consumer goods like door handles for durability.

Zinc vs. Plastic Injection Molding

Zinc parts get stronger features from casting than plastic. They can handle up to 120°C heat and warp less. Plastic molds are cheaper, but zinc ones give much tighter tolerances.

You can recycle 95% zinc products. Plastic, however, is not recyclable every time and also depends on its grade. It often ends up in landfills. Zinc casting produces electrical connectors, while manufacturers make toy housings with plastic.

Limitations of Zinc Casting

Plastic parts are lightweight because the zinc produces 3x heavier outputs. That is why it limits its use in lightweight applications.

Also, the deeply thinner wall part and intricate design might be challenging for zinc casting. This is because it can crack during ejections.

Conclusion

Zinc casting is an affordable process. Manufacturers use it to produce large production parts with more accurate features and fine quality. There are many industries that use this process, automotive, electronics, and medical devices being the most common.

The process offers very flexible designs and supports high-volume needs. Make parts more affordable, precise, and long-lasting using zinc casting in your next design.