Anodizing vs. Hard Anodizing: The Differences in Surface Treatment Techniques

Published Dec 27, 2024, updated Dec 26, 2025

2 min

In modern CNC machining, surface treatment techniques are indispensable for elevating the performance and longevity of metal components. Among these, anodizing and hard anodizing stand out as common methods, each offering unique processing advantages and distinct product characteristics.

Anodizing vs. Hard Anodizing

What is Anodizing

Anodizing is an electrochemical process that increases the corrosion resistance and wear resistance of a metal surface by forming an oxide layer. This process is commonly performed on metals such as aluminum and magnesium. During anodizing, the metal component serves as the anode and is placed in an electrolytic solution, where an electric current is applied to induce oxidation reactions, resulting in the formation of a dense oxide layer.

The oxide layer formed through anodizing is typically thin, with relatively low density. The hardness of the oxide layer generally ranges from 150 to 300HV, offering moderate wear resistance. While anodizing provides a degree of protection and decorative effects, its performance may not suffice for applications requiring higher demands on metal surface properties.

What is Hard Anodizing:

Hard anodizing is an enhanced form of anodizing that strengthens the oxide layer's hardness, density, and wear resistance by incorporating special processing steps and additives. These additional steps and additives result in a thicker, harder, and more durable oxide layer.

Compared to regular anodizing, hard anodizing yields an oxide layer with significantly higher hardness and density. The hardness of the oxide layer typically exceeds 400HV, reaching even 1000HV or higher. This elevated hardness imparts outstanding wear resistance and corrosion resistance to the metal surface, making hard anodizing suitable for more demanding industrial environments.

Application Areas:

While anodizing is suitable for general metal surface treatments such as protection and decoration, hard anodizing finds greater utility in industries with higher demands on metal surface properties, including aerospace, automotive, and mechanical manufacturing sectors. It is particularly effective for components requiring superior wear and corrosion resistance.

Conclusion:

In conclusion, anodizing and hard anodizing represent two distinct metal surface treatment methods, differing primarily in processing techniques and final product characteristics. Hard anodizing, through improved processing techniques and oxide layer properties, enhances the hardness and wear resistance of metal surfaces, thereby expanding its applicability in industrial settings. Choosing the appropriate surface treatment method is essential for ensuring the durability and reliability of metal components in various working environments.

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