Zamak 5 is part of the zinc alloy category. Zamak 5 is a zinc alloy with 3.5-4.3% aluminum, 0.03-0.08% magnesium, and 0.75-1.25% copper. It has a tensile strength of 330 MPa, density of 6.7 g/cm³, and melting point of 380-385°C. It is used for die-casting high-strength parts in automotive, aerospace, and consumer goods.

In this article, learn its casting process, physical, mechanical, and chemical properties, along with its key benefits.

Composition and Properties of Zamak 5

Chemical Composition of Zamak 5

A zinc-based alloy, Zamak 5 consists of four elements. That is zinc, aluminum, copper, and magnesium. These elements bring significant changes in the role of its performance.

Zinc (96-98%):

Zinc is the base of the Zamak five alloy. It goes well with die-casting techniques because of its low melting points. Go for zinc that is 99.99% pure. This is because the impurities in alloys affect the mechanical properties of parts.

For instance, lead (above 0.003%) or cadmium (above 0.002%) can weaken or crack parts. Also, the pure condition of zinc resists corrosion well.

Aluminum (3.5-4.3%):

The contribution of aluminum in Zamak 5 is to strengthen it by refining its microstructure. During the solidification, aluminum forms intermetallic phases. It refines the structure and strength as a result.

For example, in the given image, the solid solution shows the zinc-rich part solidifies at 381°C. Meanwhile, the Al-rich phase forms when it reaches 277°C.

The phase purposely dictates hard and ductile regions. That is because adding aluminum below 3.5% causes cracks, or when exceeding 4.5%, it raises brittleness and is more likely to fracture.

Magnesium (0.03-0.08%):

The magnesium content in Zamak five blocks impurities at grain boundaries. That is why it has become able to avoid intergranular corrosion. Also, its addition makes the fluidity of the alloy much better, filling the mold evenly during casting.

Excessive amounts of magnesium are not good for hot chamber die casting (at 385°C). Because of its oxidation, dark spots occur on the surfaces. It somehow needs very strict control during operation.

Copper (0.75-1.25%):

Copper in the Zamak 5 alloy strengthens its ability. They can handle high temperatures. Specifically when it is around 150°C. The alloy structure stabilizes. That, therefore, increases its creep resistance compared to copper-free zinc.

Copper also works to maintain the mechanical properties of the alloy. It slows down its aging, lasting more than 10 years.

Also, the overuse of copper above 1.25% leads to brittleness, and the reduced amount causes elongation up to 30% conversely.

Physical Properties of Zamak 5

Density:

There is a 6.7 g/cm³ tensile strength in Zamak 5. Its density impacts its weight, making it a 15% lighter option than steel (7.85 g/cm³). Compared with aluminum alloy (2.7 g/cm³), it is, however, 60%-heavier.

Melting Point:

The Zamak 5 alloy basically contains lower melting points that range between 380°C and 385°C. So as a result, they also consume 25% less energy than aluminum ones.

Moreover, during the casting process, Zamak 5 content solidifies very quickly within 0.8 seconds. That alternatively aids in completing its one cycle in around 20 seconds.

Tensile Strength, Yield Strength, Elongation:

Around 330 Mpa tensile strength is present in Zamak 5. Also, it has 220 mpa yield strength. The alloy, however, can be stretchable up to 7-10% before breaking.

Moreover, tensile strength drops at temperatures of 150°C  or above. This is because of its thermal softening or microstructural changes.

The stress-strain curve in the image shows linear elastic regions. That is around 220 MPa. Also, plastic deformation follows it.

The increment in tensile strength around 15% happens because of smaller grain size (0.02 mm). It blocks dislocation movement.

Mechanical Properties of Zamak 5

Hardness:

The Zamak 5 grade has 91 hb ( Brinell hardness). Pressing a 10-mm steel ball with a 295 N force aids in getting this measurement. This process lasts 15 seconds, leaving a 3.2 mm dent.

Hardness features surface to prevent scratches. This makes the alloy suitable for items like decorative or door handles.

Impact Resistance:

Charpy impact strength of Zamak 5 grade. That can be 53 J at 20. This, however, drops to 35 J when ductility reduces to -20°C.

The toughness of the grade matters whenever there is a need to produce parts that are exposed to vibration.

Fatigue Strength:

You can handle up to 100 Mpa cyclic stresses with Zamak 5 for completing 1 million cycles. However, the result of a rough surface (Ra > 1.6 µm) or sharp edges affects the limit and leads it to 70 Mpa. Competing against constant vibration, zamak5 suits washing machine equipment.

Advantages of Zamak 5 Alloy

High Strength-to-Weight Ratio

There is a 49 Mpa strength-to-weight ratio in a zinc aluminum alloy, Zamak 5. It has good tensile strength and density. That is much higher (30%) than the A380 grade of aluminum and around 50% more lightweight than C93200 copper.

In addition to this, the impact strength of Zamak 5 alloy 53 J beats A380 aluminum (40 J) and ZA-12 (45 J). This is the reason for this grade’s suitability in lighter and high-strength parts. That can be drill housings and bicycle pedals.

Good Corrosion Resistance

Exposure to humidity  (85% RH) or salty environments may lead to rust on parts. For this case, the chemical compositions (0.08% magnesium) avoid rust.

This metal survives salt spray tests for around 500 hours and surprisingly shows surface erosion chances of fewer than 0.1 mm.

These kinds of grades usually work well for resisting corrosion in marine hardware. For example, it can stop corrosion without coatings in parts like boat cleats and deck hinges.

Excellent Castability

Zamak 5 fills the mold with 95% fluidity. It offers excellent castability, being an alloy that creates intricate shapes. For example, it can design watch gear by adding 0.5 mm teeth or a laptop hinge.

Castings produce parts with very thicker walls, so they take less time for cooling. That also reduces production costs by up to 40%, in contrast to CNC-machined brass.

High Ductility

Without breaking, a Zamak 5 alloy is stretchable, around 7-10%. Its high ductility enables cold forming. That is needed for plumbing elbows or electrical connectors to prevent cracks. This kind of machinability aids in secondary operations (threading or drilling).

Applications of Zamak 5

Automotive Industry

Zamak 5 alloy makes automotive parts. That includes injector nozzles, sensor housings, and transmission brackets.

It gives dimensional stability (tolerance) up to ±0.05 mm in parts like engine mounts. So that they perfectly fit, competing against the highest vibrations.

Aerospace Industry

Because of the mechanical attributes of Zamak 5, manufacturers make noncritical parts like cabin light bezels or air vent slats. However, it limits its use below 150°C temperatures.

Construction Industry

Construction sectors use Zamak 5 to make door handles, window locks, or even roofing brackets. They benefit from its fine, polished look.

Fingerprints and tarnish can damage faucet handles’ appearance, which is exactly why you need to apply chrome coatings.

Consumer Goods Industry

Zamak 5 is a high-strength grade. This can shape camera lens mounts, blenders, bases, and zipper sliders. Also, it has good weldability.

This means laser types can work on components like seams in smartphone frames at 200 mm/min. That is the reason for its reduced assembly cost.

Difference Between Zamak 5 and Zamak 3

1. Comparison of Chemical Composition:

The major difference is that the Zamak 5 contains copper. This is why it increases high-temperature resistance.

Meanwhile, the Zamak 3 has very little copper. However, it is for improved castability and corrosion resistance in environments like humid.

2. Comparison of Mechanical Composition:

Zamak 5 has a better and higher amount of strength and hardness. So these go well for manufacturing load-bearing parts.

Conversely, there is higher ductility in the alloy of Zamak 3. It supports complex and difficult bends.

Comparison of Applications

Zamak suits parts in which dimensional stability is necessary. For example, automotive engine brackets and industrial valve bodies.

Low-cost die-casting alloy, Zamak Three manufactures smooth surface parts. Like toys or decorative lamp bases.

Selection Factors:

• Strength vs. Cost: Zamak is around 12% more costly than Zamak 3. However, it lasts up to 50% in harsh environments.
• Corrosion Resistance: Zamak 3 offers better corrosion resistance and is ideal for coastal faucets. Meanwhile, zamak 5 gives good wear resistance in parts like machined gears.
• Load Type: The presence of higher hardness in Zamak 5 enables it to compete with dynamic loads (e.g., gears, pump components). Zamak 3 works well for static items like decorating trim.
• Surface Finish: Zamak 3 gives a very attractive and polished finish, which meets the needs of jewelry clasps. Meanwhile, zamak 5 needs additional layering of coating to produce an aesthetic look.
• Regulatory Compliance: Zamak 5 meets the ASTM B240 rule for automotive. It makes heat-resistant parts. Zamak 3 follows iso 301 standard working for cost-sensitive goods.

Manufacturing Process of Zamak 5

Die Casting Process

Hot chamber die casting works well with zinc-aluminum alloys, so the Zamak five can be cast in it. It has low melting points and can heat up at 400°C for optimal fluidity.

The molten alloy is injected into the mold cavity made of steel. The manufacturers apply 1000 to 3000 bar pressure. It takes on solid form in a few seconds, containing tight tolerances.

This technique can work for larger production, gaining smooth surfaces (1.6 µm). It also lessens post-processing needs.

Zinc casting is a very affordable manufacturing method. This is why it is chosen by most mass-productive platforms. That includes automotive brackets or consumer electronics housings.

Process Parameters

The important parameters are:

• Injection pressure (700–1000 bar). It prevents defects,
• Die temperature (150–200°C) to avoid premature cooling
• Cooling rates (50°C/s) support refined grain size (0.02 mm).

Adjusting these steps is important to get actual output results. It increases mechanical properties like tensile strength.

These parameters also prevent variant variables in parts. Appropriate cooling systems reduce internal defects and improve fatigue resistance.

Machining and Finishing

Zamak 5 grade can be machined at cutting speeds of 150m/min. Its feed rates fluctuate around 0.1 mm/ revolution. That depends on the carbide tool.

Cooling channels that are water-based take away excessive heat. That alternatively supports highly accurate threading or grooving.

Making parts with a high-quality finish is one of the most required steps. After electroplating, the parts will resist corrosion better.

In various finishing options, manufacturers apply powder coating to architectural hardware to add a durable finish. Meanwhile, coatings of paint perfectly adhere to decorative items like lamp bases.

All of the above, concerning environmental impact, is much more important. So, adopt eco-friendly practices. For example, closed-loop water systems can be used to apply powder layers.

Conclusion:

Zamak 5 is a zinc-based metal. It contains many elements like aluminum, magnesium, and copper. This is why they have a better strength-to-weight ratio, corrosion resistance, and excellent castability. You use die-casting techniques to meet mass production demands. It is cost-effective and outperforms alternatives like Zamak 3 or aluminum.