Why Smartwatches Are Upgrading Their Cases To Aluminium Alloy

The smartwatch has upgraded its case material to aluminium alloy, which is an optimised choice made after comprehensively considering various factors such as product experience, performance, cost, and design. The specific reasons are as follows:

1. Lightweight advantage, improving wearing comfort

- The density of aluminium alloy is approximately 2.7 g/cm³, significantly lower than that of stainless steel (7.9 g/cm³) and titanium alloy (4.5 g/cm³). For smartwatches that require prolonged wear (often exceeding 12 hours daily), a lightweight case significantly reduces wrist discomfort.

- For example, a 42mm-diameter aluminium alloy case typically weighs between 20-30g, while a stainless steel case of the same size may weigh 50-70g. This weight difference has a noticeable impact on comfort during daily wear (especially during activities like exercise or sleep), helping to reduce wrist fatigue and discomfort caused by movement.

2. Excellent corrosion resistance and stability, suitable for daily environments

- The surface of aluminium alloy naturally forms a dense oxide layer (Al₂O₃), which effectively resists corrosion from sweat, rainwater, and daily hygiene products (such as hand soap and skincare products), eliminating the need for additional electroplating layers like those required for stainless steel cases.

- After undergoing processes such as anodising, sandblasting, and PVD coating, the scratch resistance and colour retention of aluminium alloy cases are further enhanced. For example, the aluminium alloy case of the Apple Watch combines ceramic shield glass with anodising technology to ensure both durability and aesthetic appeal.

- Compared to stainless steel, aluminium alloy is less prone to rusting from contact with seawater or sweat, making it more suitable for high-frequency daily use scenarios.

3. Easy to process, offering greater design flexibility

- Aluminium alloy is relatively soft in texture, making it easy to shape through processes such as stamping, cutting, and CNC machining. This enables the creation of complex case designs (e.g., curved designs, perforated structures) or intricate surface textures (e.g., brushed, matte, or satin finishes), catering to diverse design preferences.

- Its surface treatment processes are well-established, and anodising can produce a wide range of colours (such as silver, deep space grey, gold, blue, etc.), with strong colour adhesion and resistance to peeling, aligning with the trend towards youthful and personalised designs in smartwatches and attracting more fashion-conscious consumers.

4. Cost-effective, balancing performance and price

- The raw material cost of aluminium alloy is lower than that of titanium alloy and stainless steel, and it has lower processing difficulty, thereby reducing production costs.

- This allows smartwatches with aluminium alloy cases to maintain basic performance such as lightweight and corrosion resistance while effectively controlling the selling price, catering to a broader consumer base, especially mid-range and entry-level products, thereby enhancing the product's market competitiveness.

5. Compatibility with smartwatch functional characteristics

- Smartwatches typically integrate multiple sensors and wireless charging functionality. Aluminium alloy has moderate conductivity (better than plastic but weaker than pure metals), which does not overly interfere with wireless signals (such as Bluetooth or NFC) or affect the magnetic field transmission of charging coils, ensuring normal device functionality.

- Compared to plastic cases, aluminium alloy offers better heat dissipation, helping to cool the internal chips of the watch and prevent performance issues caused by overheating from prolonged use.

In summary, aluminium alloy, with its lightweight, corrosion resistance, ease of processing, cost advantages, and compatibility with smartwatch functions, is an ideal choice for upgrading watch case materials. It not only enhances the user experience but also meets the comprehensive requirements of the product in terms of design, performance, and price.

What are the advantages of coloured aluminium in the manufacture of watch cases?

Coloured aluminium (i.e. aluminium alloy with a surface colour treatment) combines the basic properties of aluminium alloy with the advantages of colour in the manufacture of smartwatch cases. Its core advantages can be explored from three dimensions: functional experience, design expression, and durability.

1. Rich and stable colours to meet personalised design needs

Diverse colour options: Coloured aluminium achieves colouring through anodising (rather than traditional spray painting), enabling the presentation of dozens of colours such as silver, deep space grey, gold, blue, and green. It can even create unique visual effects through techniques like gradients and two-tone combinations (e.g., Huawei Watch GT series' Starry Blue and Honor Magic Watch's Dawn Orange).

Strong colour adhesion: The colours formed through anodisation are tightly bonded to the aluminium base, making them resistant to peeling or chipping (superior to the spray-painting process used on plastic cases). They remain vibrant even after prolonged use, aligning with the smartwatch's requirements for ‘frequent wear + lasting appearance.’

Aligns with youth-oriented trends: The diverse colour palette caters to different aesthetic preferences (e.g., vibrant orange for sports models, deep space grey for business models), helping brands reach a broader consumer base (especially younger users).

2. Retains the lightweight and comfortable wearing experience of aluminium alloy

Coloured aluminium is essentially an aluminium alloy substrate with a density of approximately 2.7 g/cm³, significantly lower than stainless steel (7.9 g/cm³) and titanium alloy (4.5 g/cm³).

For devices like smartwatches that require prolonged wear, a lightweight case significantly reduces wrist pressure (e.g., a 42mm coloured aluminium case weighs approximately 20-30g, over 50% lighter than a steel case of the same size), making it particularly suitable for scenarios like sports or sleep, where weight-related shaking or fatigue can be avoided.

3. Enhanced surface hardness and corrosion resistance

Anodised coating for enhanced protection: The colouring process of coloured aluminium involves anodising, which forms a 5-20μm-thick oxide layer (Al₂O₃) on the surface. This layer has a hardness of approximately 300-500HV, exceeding that of the base material, and can withstand minor scratches from daily use (e.g., contact with surfaces or keys).

Excellent corrosion resistance: The oxide film is dense and chemically stable, effectively blocking corrosive substances such as sweat (containing salts), rainwater, and skincare products, preventing the case from rusting or discolouring (superior to untreated aluminium alloy and even surpassing the protective coating of some low-cost steel cases).

Strong weather resistance: The oxide film is heat-resistant and UV-resistant, and does not fade easily even when exposed to sunlight for extended periods, making it suitable for outdoor use scenarios (such as mountain climbing or running environments).

4. Easy processing and cost control

Aluminium alloy is easy to stamp and CNC machine, and the colouring process (anodising) is mature and less expensive than stainless steel PVD plating or titanium alloy precision machining. This allows for complex shapes (such as curved cases and micro-curved bezels) while controlling production costs.

This enables smartwatches with coloured aluminium cases to maintain a moderate price point while balancing performance and cost-effectiveness (particularly suitable for mid-range models), ensuring ‘lightweight + vibrant appearance + basic durability.’

Summary

The core advantages of coloured aluminium cases lie in: leveraging aluminium alloy's lightweight, easy-to-process, and low-cost properties, combined with anodic oxidation colouring to achieve rich colours, scratch resistance, corrosion resistance, and long-lasting aesthetics. This perfectly aligns with the core requirements of smartwatches—comfortable wearability, stylish design, and durable practicality—making them an ideal choice for mid-range and mainstream models.