Hard anodizing is a process that converts the surface of aluminum parts into a hard and durable oxide layer through electrochemical oxidation. The layer can offer many benefits, but it also has some disadvantages.
Firstly, let's take a look at the advantages of hard anodizing. The most significant advantage is that it can improve the surface hardness and wear resistance of the parts. The hard anodized layer has a high hardness of 60-70 Rockwell C, which is similar to that of hardened steel. This hardness can protect the parts from mechanical damage and wear, extending their lifespan. Moreover, hard anodizing can also enhance the corrosion resistance of aluminum parts. The oxide layer can prevent the metal from oxidizing, rusting, or reacting chemically with other substances.
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However, there are also some disadvantages of hard anodizing. One of the most significant disadvantages is that the process can induce dimensional changes in the parts. The thickness of the anodized layer can vary depending on the processing conditions, and the layer can sometimes cover the tight tolerances required by the design. This means that extra finishing may be required to meet the specifications.
Another drawback of hard anodizing is that it can affect the electrical conductivity of the parts. The oxide layer can act like an insulator and reduce the parts' electrical conductivity, which may not be suitable for some applications. Moreover, the hard anodized layer can also add some color to the parts, which may not be desirable in some industries.