What is ZAMAK? Zinc Die Casting Alloy
When people refer to zinc castings, they are almost always referring to an alloy of zinc. Zinc by itself is actually quite soft, making it a poor material for manufacturing applications. However, if you mix zinc with small amounts of aluminum, magnesium, and copper, you can create an exceptionally strong yet fluid blend of metal called ZAMAK.
But if that is the case, why not call it “Zamac” instead of “Zamak”? That’s because the acronym comes from the German spellings of the elements. Zink, Aluminum, Magnesium, and Kupfer (the German word for copper).
That being said, you may see it spelled ZAMAC with an English spelling instead of the common ZAMAK spelling. ZAMAK alloys are a separate family from the zinc-aluminum (ZA) alloys. However, they both maintain a consistent composition of 4% aluminum.
The manufacturing process varies between the ZA alloys and the ZAMAK alloys. ZA uses a cold chamber die casting process similar to aluminum die casting. Therefore, it requires special melting procedures and high-temperature operations.
Typically, manufacturers like DECO use ZAMAK alloys in hot chamber die-casting. This alloy works best in high-pressure applications to achieve faster production cycles and optimal material flow.
Brief History of ZAMAK
Precision metal alloys are a crucial component in the manufacturing process that has transformed metal casting.
In the 1920s, metallurgists first introduced ZAMAK for high-pressure die casting. This development represents a groundbreaking innovation that has significantly impacted the zinc die casting industry.
Before the innovation of ZAMAK, manufacturers in the automotive and toy industries compiled various low-cost metals with lower melting temperatures. They subsequently melted down these “pot metals” mixtures and cast them into distinct parts. Unlike today’s precision metal alloys, this pot metal led to all sorts of problems. The uncontrolled composition of pot metal resulted in unexpected properties and poor surface finish quality.
High-precision zinc alloys emerged as a solution to the problems of uncontrolled pot metal, with ZAMAK leading the way. After its development in 1929, precision zinc alloys took over the zinc die casting industry.
ZAMAK retained the initial benefits of the pot metal, such as a low melting point and being easier to handle. But radically improved the performance of the metal. The ZAMAK metal had excellent reliability, surface finish, and offered a high-strength alternative to pot metal. ZAMAK remains the most extensively utilized alloy in the zinc die-casting industry for producing high-quality parts.
Why Choose Zinc Alloys for Die Casting?
Engineers and designers have many material options to choose from when designing a casting, so why do they choose zinc? Many of the benefits of using a zinc alloy are directly derived from its low melting point and high fluidity:
This means it is easy to work with and cheaper to melt. The lower temperature of zinc makes it easier on equipment and tools, reducing the overall capital cost to support ongoing manufacturing.
Compared to other metal types for casting, zinc is:
- less expensive to melt
- easier on tooling and equipment, enhancing tool life and lowering tool cost
- able to achieve faster cycle times, lowering total cost
- able to fill complex shapes with higher levels of precision
- better at providing a smooth surface finish right out of the die
- able to eliminate downstream operations that can be designed into the casting
- cost-effective for high production volumes
The Most Common Zinc Alloys
At Deco Products, ZAMAK #3 represents the most popular of the alloys, with over 70% of all zinc die casting in alloy #3. The reason is its excellent balance of physical and mechanical properties. This casting material offers outstanding performance in high-volume production while maintaining consistent quality.
However, our customers also use #2, #5, and #7 in significant volumes. These different alloys provide slightly different performance characteristics. Although we initially design with #3 in mind, our engineers may make an alternate suggestion on material or design depending on the needs of your product.
Choosing The Right Zinc Alloys
Product engineers and designers will compare all die-cast zinc alloys for a new product design. Understanding the end use of the cast component is essential to selecting the correct alloy.
Each ZAMAK alloy fits specific castings:
- ZAMAK 3: Best overall balance of properties for general casting parts
- ZAMAK 2: Highest strength for demanding structural castings
- ZAMAK 5: Enhanced hardness and strength with copper addition
- ZAMAK 7: Improved fluidity for complex shapes and thin-walled sections.
Listen to this guest podcast episode where Dave Magner discusses the fluidity of zinc.
Frequently Asked Questions: ZAMAK
ZAMAK alloys work well for thin-walled designs and net-shape manufacturing.
Zinc creates metal parts with great dimensional stability through high-pressure die casting. This precise process reduces machining needs. ZAMAK becomes a wise choice for high-quality parts production.
Q: Does casting in zinc require costly machining, or can I cast complex shapes?
A: Molten zinc flows easily. This allows casting of fine details and tight tolerances. These features would be hard to achieve with cast iron or other casting materials.
Zinc fluidity also allows for casting to tight tolerances and dimensional accuracy. The casting to final shape reduces or eliminates costly machining.
Q: Are you able to apply a finish to ZAMAK alloys to achieve an attractive appearance?
A: ZAMAK allows for several finishes such as paint, plated, or powder coating, providing an appealing look and texture. The ZAMAK material also forms a natural patina when exposed to oxygen, allowing parts to be sold in an as-cast finish and not be highly susceptible to corrosion.
Q: How does the strength-to-weight ratio of zinc alloys compare to other materials?
A: Zinc alloys are stronger per unit weight than many other common materials, offering a favorable strength-to-weight ratio. This is especially true for impact resistance. This makes zinc die-cast parts ideal for applications where both strength is important, but the design is complex.
Zinc alloys provide higher tensile strength compared to most plastics and lower-density metals. They also maintain excellent dimensional stability and thin-wall capability, which further contributes to their efficiency in structural applications.
Q: What can a manufacturer expect in long-term tool life with a zinc die cast mold?
A: Zinc generally offers longer tooling life compared to other casting materials. A typical zinc mold can last upwards of 750,000 shots. Depending on the tool design, a tool may last well into the millions.
In parts with a high volume, zinc offers a cost-effective solution.
ZAMAK: The Zinc Advantage
Whether you need complex shapes, corrosion-resistant properties, or cost-effective production for high volumes, ZAMAK alloys deliver consistent performance in the manufacturing process.
Interested in learning more about Zinc? Check out our zinc alloys page to learn more about zinc alloy use at Deco Products.