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Hard Anodizing and Soft Anodizing, Which one is better for my project?


Anodization, the electrochemical oxidation of metals or alloys. It's a process, in which aluminum and its alloys form an oxide film on an aluminum product (anode) under a corresponding electrolyte, and a specific process condition due to an applied current. In order to overcome the defects of surface hardness and wear resistance of aluminum alloys, to extend the application range and prolong the service life, the surface treatment technology becomes an indispensable part in the application of aluminum alloys, and the anodizing technology is one of the most widely used and the most successful in metal industry.


Soft Anodizing and Hard Anodizing are widely used in Machinery manufacturing and processing industry, such as the rapid prototypes, customized machining products, metal parts.

Without a good understanding of anodic oxidation, engineers often do not have a idea about which surface treatment is better for their design projects. Now, please see following to get it.

Difference between soft anodize and hard anodize

Three aspects of differences in operating conditions:

1. Temperature: Soft type is 18-22 °C or so, there are additives to 30°C, the temperature is too high prone to powder or crack; Hard oxidation is generally below 5°C. On the other hand, the lower the temperature, the harder the higher.

2. Concentration: Ordinary anodize is generally about 20%, but hard type is in 15% or less.

3. Current/Voltage: Soft oxidation current density is generally 1-1.5A/dm2; However hard oxidation is 1.5-3A/dm2.


Four aspects of differences in coating properties:

1. Thickness of coating: Hard oxide layer thickness generally > 15μm, too low to reach the hardness requirements, while the soft anodize is thinner.

2. Surfaceness state: The surface of soft anodize is smoother.


3. Porosity: Hard anodize is a little higher.

4. Application: Hard anodize is for wear-resisting and power-resistant mainly. But soft anodizing is for scratching and decorating.

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