亜鉛は多目的で重要な金属であり、幅広い工業、商業、生物学的用途において重要な役割を担っている。亜鉛はその高い耐食性と青みがかった銀色の外観から、工業用、建築用、保護塗料用として使用されています。その最も貴重な特性のひとつは、特にアルミニウム、銅、マグネシウムと非常に強い合金を形成する能力で、強度と耐久性を大幅に向上させます。ダイカスト鋳造のような製造工程に関しては、これらの特性により亜鉛は非常に適しています。このような機械的特性を持ち、同時に多くの製造上の利点を持つ材料は他にないからです。機械加工をほとんど必要とせず、非常に複雑で詳細な形状を作ることができるため、装飾的な車両部品にも機能的な車両部品にも最適です。さらに、融点が低いため、世界的な持続可能性の目標に従って、製造時のエネルギー使用量を少なくすることができる。自動車技術の進化に伴い、亜鉛の重要性は増している。現在、航空機のシステム部品のほとんどは、亜鉛で製造することができます。なぜなら、亜鉛は部品の一貫性に優れ、大量生産に対応しているからです。

亜鉛ダイカストとは？

Zinc Die Casting is a precision manufacturing process that involves injecting molten zinc alloy into a custom die (also known as a mold) under high pressure and at high pressure to form metal parts. It is normally used for the production of complex, detailed components with tight tolerances, fine surface finishes and high mechanical properties.

Zinc die casting has excellent mechanical properties and combines high precision at the same time. It permits the manufacture of intricate, close tolerance parts with smooth surface finishes and is useful for the requirements of present day vehicle design.

Why Zinc? 主要材料特性

For several unique properties, zinc is preferred in the die casting process.

高い強度と延性

Because it is stronger than many other metals that are die cast, in thin walled applications, zinc alloys are used.

優れた寸法精度

Zinc die casting is a part that maintains their shapes and sizes with great consistency which helps to cut away from post processing.

優れた耐食性

Zinc is naturally resistant to corrosion particular to the additional coatings. It is crucial for parts used in vehicular conditions in the unfortunate presence of road and weather conditions.

高い流動性

The molten zinc flows very easily, and these parts with small features and thin walls were successfully cast.

費用対効果の高い金型

Zinc casting benefits from long-life dies compared to aluminum or magnesium; therefore, there is more economic advantage in zinc if a large production run is desired.

リサイクル性

The automotive industry’s transition towards greater sustainability also means that zinc is an environmentally responsible material that is 100% recyclable without loss of properties.

製造工程：ステップごとの概要

1.設計と金型：

CAD software is used for designing the component by engineers. Then, a high precision steel die is manufactured with a high number of cavities to build several parts in a single cycle.

2. 亜鉛合金を溶かす：

At about 420°C (788°F) zinc is melted, lower than aluminium and with considerably lower energy costs.

3.注射：

Usually, the molten zinc is injected into the die at a pressure of 1,500 – 25,000 psi high enough to ensure that the mold is filled quickly and evenly.

4.冷却と凝固：

When the zinc alloy gets into the die, it rapidly cools and solidifies (a matter of seconds).

5.退場：

Ejector pins then eject the newly formed part from the die.

6.トリミングと仕上げ：

The part may be subject to additional finishing, such as deburring, polishing, painting, or coating, and the excess material (flash) is removed.

7.品質管理：

Some components are inspected for dimensional accuracy, surface defects, and mechanical integrity, as is often with automated systems or 3D scanners.

自動車産業で使用される一般的な亜鉛合金

In the automotive industry, the selection of the proper zinc alloy is important because the properties of the alloy play an important role for the proper performance, reliability and for proper cost efficiency. Manufacturers can match materials to specific applications depending on what balancing of strength, ductility, fluidity, and corrosion resistance various alloys have to offer in varying measures. The most commonly used zinc alloys in automotive die casting are given below.

1.ザマック合金（亜鉛アルミニウム合金）

The primary alloying element in a family of zinc alloys known as zamak is aluminum at about 4%. The name comes from the German names of the metals used: Zink, Aluminum, Magnesium, and Kopper (copper).

ザマック3

• It is the most widely used zinc alloy for die casting.
• Offers excellent dimensional stability, good surface finish, and cast ability.
• These surfaces are common in interior components such as door handles, knobs and trim parts.

ザマック5

• It is slightly more copper than Zamak 3 and offers higher strength and hardness.
• Appropriate for mechanical stress applications like structural brackets.

ザマック2

• The strongest and hardest of the Zamak alloys.
• This is used in locking systems or gear housings where wear resistance is critical.

2.ZA合金（亜鉛アルミニウム合金）

ZA alloys (ZA-8, ZA-12, ZA-27) have higher Al content than Zamak, having higher strength and wear resistance. They’re generally used in gravity casting presumably in some cases in die casting too.

ZA-8：

• Contains 8% aluminum.
• Offers good strength and moderate casting properties.
• Suitable for structural components in lightweight vehicles.

ZA-12とZA-27：

• Hard to cast, but higher strength.
• Used in semi-structural applications or parts, where it is subject to friction.

3.ACuZinc5

It is a special zinc copper aluminum alloy intended to obtain the characteristics of cast ability of Zamak and the strength of ZA alloys.

• Extremely high strength and superior wear resistance.
• Applied in gear housings, actuators, and mechanical linkages in automotive systems.
• The change material is ideal for replacing machined bronze and steel in applications where durability is necessary.

4.EZAC（強化亜鉛-アルミニウム-銅）

A relatively new alloy, very high in strength and creep resistance up to elevated temperatures, EZAC is.

• Good for parts that have to hold shape and strength even under the load, for example mounting components or engines.
• It offers twice the strength of Zamak 3, but requires more advanced tooling.

5.亜鉛-ニッケル合金

Zinc-nickel plate is less common than zinc die casting for these areas, but it is frequently used to improve corrosion resistance (especially salt and moisture) for under the hood or undercarriage parts.

• 正しい合金の選択
• The selection of zinc alloy depends on several factors
• Mechanical requirements (tensile strength, impact resistance)
• Surface finish needs
• Cost and production volume
• Exposure to environmental stress (heat, corrosion)

For that reason, engineers frequently work with material scientists and suppliers to choose an alloy that is as well suited to the task as cost may permit, meeting both performance and cost constraints.

自動車産業における亜鉛ダイカストの役割

Zinc die casting has great importance in automotive manufacture due to high precision, high strength and economical make of small-to medium sized components. This process offers the means to produce complex parts of high precision in a very short time period and is excellent for high volume automotive applications.

Excellent mechanical properties of zinc alloys, such as durability, corrosion resistance, and dimensional stability, are obtained. These are the things that make zinc the best choice for door handles, brackets, locks, emblems, etc., as an auto part. This also provides easy plating or painting since it has a smooth surface finish.

Although zinc is heavier than aluminum or magnesium, it can be competitive for applications where weight is not the highest priority in terms of strength and detail. Due to its low melting point it requires less energy usage and has a long tool life. Zinc also is 100% recyclable, which supports accelerating the automotive industry’s promotion of sustainability.

Zinc die casting is still providing reliable and high-quality solutions for automotive demanding applications as vehicle designs evolve.

亜鉛の物理的・化学的性質 

亜鉛の物理的性質

1.外観：

The thermoelectric bluish silver or grayish metal has a shiny metallic luster when freshly polished.

2. 密度：

Since at room temperature Zinc has a density of about 7.14 g/cm³, it is moderately heavy in comparison with other metals.

3.融点：

However, at a relatively low temperature of 419.5°C (787°F), zinc is suitable for thermal processes, such as die casting, where low energy consumption is desired.

4.沸点：

Zinc boils at 907°C (1665°F).

5.硬度：

Zinc is about 2.5 on the Mohs scale of hardness, which makes it not too hard compared to steel, but not too soft as pure tin or lead are.

7.電気伝導率：

However, while copper and silver are very good conductors of electricity, zinc is not quite as conductive. Because of this property, it is often used in batteries and electroplating.

8.熱伝導率：

The moderate thermal conductivity of zinc makes it useful in managing heat, but it is less efficient than aluminum.

9.可鍛性と延性：

Zinc is brittle, and thus can easily break at room temperature. It is however malleable when heated to around 100–150°C (212–302°F), one can easily shape them.

10.結晶構造：

In addition binary compounds of zinc are zinc crystallizing in a hexagonal close packed (hcp) structure which affects the mechanical properties especially the brittleness at lower temperatures.

亜鉛の化学的性質

1.空気との反応性：

After coming in contact with air, zinc forms a thin layer of zinc oxide (ZnO) on the surface. Zinc on the top side prevents deeper corrosion and is therefore very resistant to atmospheric oxidation rusting.

2.酸との反応性：

Dilute acids like the dilute acid hydrochloric acid (HCl) can react easily with zinc to give up hydrogen gas (H₂). Therefore, this property makes zinc useful in galvanization and sacrificial anodes for corrosion protection.

3.両性具有：

Zinc is amphoteric, and can be acted upon by both acids and powerful bases. For example it reacts with sodium hydroxide (NaOH) to give sodium zincate.

4.合金の形成：

Zinc readily alloys with several metals, including copper, to produce brass, aluminum, magnesium, and many other metals.

5.酸化状態：

The +2 (Zn²⁺) oxidation state of zinc is the most common. This oxidation state is combined with zinc compounds such as zinc oxide (ZnO) and zinc sulphate (ZnSO₄).

6.耐水性：

Pure water does not react with zinc at room temperature, but at higher temperatures, zinc can react with it, slowly forming hydrogen gas and zinc oxide.

7.ガルバニック活性：

The anode material, zinc, is very effective because it readily loses electrons in galvanic cells (batteries).

自動車用途における亜鉛と他の材料との比較

Unlike aluminum, magnesium, plastic or steel, zinc die casting has several advantages. Zinc shines for its key performance and cost in automotive design, and while each material may have its place in automotive design, zinc is particularly effective in those parameters.

亜鉛対アルミニウム：

In a form that is often selected for its light weight, aluminum is too weak and too soft at low thicknesses compared with zinc. Additionally, zinc provides better dimensional stability and additional complex geometries don’t require extensive machining. Tooling for this kind of casting also tends to last for longer periods, so it means that long term production costs are lower.

亜鉛とマグネシウムの比較

Zinc is lighter than magnesium but is more expensive when bought without special coating. However, zinc alloys offer excellent corrosion resistance and do not require any additional surface treatments to make them resistant in most environments. Also, casting zinc provides better casting precision and finish.

亜鉛対プラスチック：

However, plastic is lightweight, inexpensive, but comparatively weaker, does not withstand temperatures very well and is less durable than metal. Zinc components withstanding wear, impact or load bear are a solid alternative when structural integrity, lifespan and resistance to damage from impact or wear are important, in particular where movement or load carrying is involved.

亜鉛対スチール：

Steel is a good material that is strong and is quite commonly used in structural applications, but it is much heavier, and in many cases, more costly to form into ornery shapes. Zinc die casting, because it produces near net shape parts with minimal post processing, is well suited in cases where small and medium sized components are to be produced.

In general, zinc provides a good balance between mechanical strength, cost, formability, and surface finish and is therefore an excellent material for automotive parts regardless of their function.

亜鉛の主要特性の概要表

自動車製造における亜鉛ダイカストの用途

A wide range of components for vehicles can be processed via zinc die casting. Some of which are most common, such as:-

1. Interior Components:

• ドアハンドル
• Seat belt hardware
• Dashboard control levers
• HVAC knobs and switches

The components in these are high precision, tactile feel needs to be good, and the fit has to be a great finish. The ability of zinc to provide fine surface detail and dimensional accuracy is suited for these parts that are visible and used frequently.

2. Exterior Components:

• Emblems and logos
• Door and trunk locks
• Mirror brackets
• Wiper system components

Since noise, however, often indicates the cause of noise and the location of its cause is not as important as the noise itself, corrosion resistance and strength are used for use after environmental exposure and give appearance and function.

3. Under-the-Hood Components:

• Carburetor parts
• Fuel system parts
• Valve bodies
• Timing belt covers

Both thermal stability, strength and wear resistance are essential for these parts. Complex geometries, high precision tolerances and fluid engine system applications are achieved through zinc die casting.

4. Structural Parts:

• ブラケット
• Mounting plates
• Chassis supports (in smaller vehicles)

Although not used for primary load bearing structures, zinc components have stiffness and reliable mechanical properties that make them useful in supporting frames and assemblies.

Zinc’s flexibility meets decoratively and functionally said requirements in all classes of vehicles. Because of its capacity to cut post-processing, EMI shielding, and component consolidation, zinc die casting extends to more and more electric and conventional platforms.

Advantages of Die Casting over Other Die Casting Materials

Although aluminum and magnesium have also been used in the automotive sector, zinc has an advantage:

It is easy to see that for small to medium sized components in which precision and strength are of great importance, zinc die casting is a very good option.

Challenges in Zinc Die Casting

Zinc die casting has some disadvantages:

Weight:

Zinc is too heavy to use in electric vehicle chassis and other applications where weight reduction is critical because it’s heavier than aluminum or magnesium.

熱特性： 

Thermal conductivity of zinc is lower than that of aluminum, so it is not suitable for heat dissipation parts like engine radiators.

Size Limitations:

For example, the tools cannot be used to cast very large components, and solidification defects can occur.

Yes, given intelligent engineering and hybrid material design, most of these challenges can be addressed.

Environmental and Sustainability Factors

Zinc die casting stands out because the global automotive industry leans towards greener practices.

100% Recyclability:

Zinc casting scraps are collected and reworked without any degradation.

Energy Efficiency:

Since aluminium has a much higher melting temperature, the energy consumption is significantly lower than with aluminium.

Long Tooling Life: 

It lengthens the die life, lessening the frequency of tool replacement, which means less waste and time without production.

As a result, companies working towards meeting more rigorous environmental regulations are drawn to zinc as it is an excellent option that won’t compromise quality or performance.

Innovations and Future Trends

Thin-Wall Technology:

Dies that have been advanced, and more fluid zinc alloys, have now enabled parts with extremely thin walls, reducing weight without losing strength.

Hybrid Assemblies: 

Also, zinc parts are being used more and more in combination with plastics or other metals for multifunctional parts.

電気自動車（EV）： 

EVs need compact and robust components for battery housings, control systems, and connectors, and zinc is showing promise because of its precision and as an EMI (electromagnetic interference) shielding metal.

Smart Tooling: 

In mass production, the use of AI and machine learning for die maintenance also helps to reduce the die life and defects.

結論

亜鉛ダイカスト is more than a manufacturing method; it’s a winning strategy to achieve the competitive automotive edge. It presents a combination that is optimal regarding mechanical strength, design flexibility, cost efficiency, and sustainability. Since vehicles are moving towards becoming lighter, more environmentally friendly, and more sophisticated, zinc die casting has an important role to carry it forward as the next generation of automotive components. Zinc has huge use from small interior knobs to powerful under hood structures in automotive manufacturing. Once innovations continue to refine their application, the years ahead will deliver even wider adoption on conventional, hybrid, and electric vehicle platforms.