Surface treatment processes for aluminum alloy die castings have their own focuses, each with limitations while improving performance. Understanding their advantages and disadvantages helps in precise selection based on specific scenarios.

The core advantage of anodizing lies in the dual improvement of hardness and corrosion resistance. The formed oxide film has a hardness of HV300-500, which can withstand frequent friction, and can achieve rich colors through dyeing, such as the deep space gray of mobile phone middle frames. However, this process has obvious shortcomings: it is difficult to form a uniform film layer inside complex cavities, and the size of parts will increase by 5-20 microns after anodizing, which may affect the assembly accuracy of precision fitting parts. In addition, anodizing works better on high-purity aluminum die castings; when the silicon content exceeds 12%, uneven film layers are prone to occur.

The biggest highlight of the electroplating process is its mirror effect and metallic texture. Multi-layer electroplating can achieve a glossiness of over 90GU, which is often used in high-end bathroom accessories. Its coating adhesion (≥5N/cm2) is far superior to the painting process, but high energy consumption and environmental issues cannot be ignored - each square meter of coating requires 20-30 liters of electrolyte, and the treatment cost of heavy metal-containing wastewater is high. At the same time, electroplating has strict requirements on the surface flatness of castings; defects larger than 0.05 mm will be directly visible, increasing the cost of pre-polishing.

Powder coating excels in weather resistance and cost balance. A 60-80 micron coating can resist temperature differences from -40°C to 120°C. After outdoor lamp housings adopt this process, their service life can reach more than 10 years. However, its disadvantages are that the coating thickness is relatively large (with a tolerance of ±5 microns), making it unsuitable for precision fitting parts; and corners of complex structures are prone to "bottom exposure", requiring additional touch-up spraying procedures.

The advantage of electrophoretic coating lies in its coating uniformity. A thickness deviation of 0.1 microns can perfectly cover the micropores of castings, making it especially suitable for parts with complex inner cavities, such as automobile shock absorber housings. However, the electrophoretic layer is relatively thin (10-20 microns), with weak impact resistance, and is easy to peel off after being hit by hard objects. In addition, there are few color options for electrophoresis, mainly black and gray, which are difficult to meet high decorative needs.

Although process combinations can make up for the defects of a single process (for example, anodizing + clear coat can enhance weather resistance), they will increase the process cost by more than 30%. Enterprises need to balance performance requirements and costs: for new energy vehicle motor shells that focus on corrosion resistance, anodizing can be selected; for smart door lock panels that pursue appearance, electroplating is more advantageous. The advantages and disadvantages of these processes are intertwined, collectively forming a "customizable" performance map for aluminum alloy die castings.