[Complete Guide to Metal Surface Treatment] Guide to Selecting 4 Major Processing Techniques, Characteristics, and Applications

1. Electroplating and chemical treatment (to enhance corrosion resistance and hardness)

• Anodizing: Specifically designed for aluminum alloys. By using electrolysis to form a uniform and dense oxide film on the aluminum surface, it greatly enhances wear resistance and corrosion resistance, and can be dyed in multiple colors (commonly used in 3C housings and bicycle accessories).
• Electroplating: including galvanizing, nickel plating, chrome plating, etc. By applying an external current, metal ions are deposited onto the surface of the workpiece, effectively preventing rust in the substrate while providing excellent metallic luster and surface hardness.
• Electroless Nickel Plating (ENP): Reacts without electricity. Its advantage lies in its ability to evenly cover complex geometries and internal hole workpieces, providing extremely high flatness for rust prevention and high hardness and wear resistance.

2. Coating Treatment (Strong Adhesion and Diverse Appearances)

• Powder Coating: Uses electrostatic adsorption to adhere to powder, then bakes and cures it at high temperature. The paint film coating is thick, impact-resistant, and rust-resistant, widely used in mechanical casings, architectural sheet metal, and outdoor equipment.
• Liquid Spraying: Traditional spray painting technology offers highly flexible color mixing, enabling matte finishes, leather textures, metallic paints, and other special textures and highly detailed appearance requirements.
• Teflon Coating: Utilizes the properties of PTFE to give metals special properties such as non-stick properties, low friction coefficient, high-temperature resistance, and chemical corrosion resistance. It is commonly used in food machinery and heating molds.

3. Mechanical Surface Treatment (Physical Improvement of Roughness and Texture)

• Sandblasting: High-pressure air sprays fine sand or glass beads against the surface, removing knife marks and oxide films, creating a uniform and elegant matte finish.
• Brushing (Hairline / Satin Finish): Brushing fine, regular parallel or hairline lines by grinding effectively covers tiny scratches, greatly enhancing the texture of stainless steel and aluminum alloy products.
• 拋光（Polishing）：利用拋光輪與拋光膏將表面推至光滑如鏡（鏡面處理），顯著降低表面粗糙度（Ra 值）。
• Vibratory Finishing: Place the workpiece and grinding stone in a vibratory groove for batch operation, mainly used for large-scale deburring, chamfering, and deglossing.

4. Heat Treatment and Formation of Films (Structural Reinforcement and Primer Protection)

• Carburizing / Induction Hardening: This heat treatment process enables workpieces to achieve the characteristics of 'the outside, tough on the inside,' with extremely wear-resistant surfaces and high core toughness. They are core processes for gears, drive shafts, and mandrels.
• Black Oxide: Forms a black ferric oxide film on the surface of ferrous metals. Its advantage is that it does not increase the thickness of the workpiece at all, making it suitable for rust prevention in high-precision fittings.