Anodizing is key to finishing parts made of aluminum and other metals.
What is anodizing?
Anodizing is a critical step in the manufacture of aluminum CNC machined parts. An electrochemical process that involves applying an oxide surface layer to metal parts, anodizing makes the part stronger and has a better surface finish. While anodizing is most commonly performed on aluminum, other substrates can also be anodized, including magnesium and titanium.
Anodizing ensures that the part is resistant to corrosion and the wear and tear of long-term use, and ensures that it retains its beauty in all conditions. In many cases, manufacturers send parts to third-party service providers who specialize in anodizing, similar to when you need heat treating, tempering, or plating.
The most common types of anodizing are Type I (chromic acid anodizing), type II (sulfuric acid anodizing) and type III, also known as hard coating. Each type of anodizing is suitable for different materials and has its own unique manufacturing parameters. Although each type has specific advantages and disadvantages, they work relatively the same way.
How does anodizing work? Let's break the process down into these simple steps:
A. Turn the part into a positively charged anode
B. Turn the metal plate into a negatively charged cathode
C. Immerse both in an acid bath
D. Applied voltage
E. Subtract aluminum ions from the part, forming pores
F. Attract oxygen ions to the surface of the part
G. The reaction forms a hard, corrosion-resistant aluminum oxide layer
What is the difference between anodizing and electroplating?
Anodizing is similar to electroplating in many ways. Comparing the two processes certainly helps to understand that anodizing is a unique and important step in the manufacture of CNC aluminum parts.
Similar to anodizing, electroplating involves placing a part in an electrolytic bath and applying an electric charge to it. The main difference is that when electroplating, the part becomes negatively charged, becoming a cathode rather than an anode.
The anode is applied to a piece of desired plating material, such as gold. As with anodizing, this circuit allows positively charged ions to flow to the cathode (part). These ions coat the part in a thin, even layer.
What does anodizing do?
Anodizing is very beneficial if you want high-quality and durable aluminum parts. Since the oxide layer is fully bonded to the surface of the material, it will not chip, peel or crack over time. The same cannot be said for paint or powder coating. Anodized finishes have a very long lifespan, thanks to the superior bonding and adhesion of the finishes.
Anodizing can also case harden the part to Rockwell 70C, ensuring the part can withstand heavy use. Because anodized parts are so durable, oiling, conditioning, or repainting are usually not required. Additionally, hard-anodized aluminum is an electrical insulator and can serve as a viable insulating material when other insulating materials prove insufficient.
In CNC processing, JR often provides customers with anodizing treatment, in this convenience, we have accumulated a lot of things that need attention, so as to ensure that the product has a higher quality and a more glossy surface. If you have needs for CNC machining, you can contact us.