Anodizing CNC Machined Aluminum: Types and Specifications
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In the world of precision manufacturing, CNC machined aluminum is prized for its excellent strengthtoweight ratio and machinability. However, raw aluminum is relatively soft and prone to corrosion and wear. This is where anodizing comes in—an essential electrochemical process that enhances the functionality, durability, and aesthetics of machined parts. For businesses seeking reliable, highvolume production of components, understanding anodizing is key to specifying the right finish for their application.
The Anodizing Process Explained
Anodizing is not a coating that is applied but an integral part of the metal itself. The aluminum part is immersed in an acid electrolyte bath and subjected to an electrical current. This causes the surface of the part to oxidize, creating a highly controlled and porous aluminum oxide layer. This layer is much harder than the base metal. Subsequently, the part is placed in a dye bath (if color is required) and then sealed, locking in the color and maximizing corrosion resistance.
Primary Types of Anodizing for CNC Machined Parts
1. Type II (Sulfuric Acid Anodizing): This is the most common type of anodizing. It produces a coating thickness typically between 0.0002" to 0.0007" (5 to 18 microns). Type II offers good corrosion and wear resistance and is excellent for accepting a wide range of color dyes, from black and red to custommatched hues. It is ideal for consumer electronics, aerospace interiors, and general mechanical components where both protection and appearance are important.
CNC machining
2. Type III (Hardcoat Anodizing): Also using a sulfuric acid bath but with tighter process controls and lower temperatures, Hardcoat anodizing creates a much thicker and denser coating. The typical thickness ranges from 0.0005" to 0.003" (12 to 75 microns). This process results in an extremely hard, abrasionresistant, and durable surface, often exceeding the hardness of tool steel. It is primarily used for parts subject to extreme wear, such as gears, pistons, valves, and military equipment. While it can be dyed, the color options are more limited, typically to shades of black, dark bronze, or gray.
Key Specifications to Define
When ordering anodized CNC machined parts, providing clear specifications ensures consistent quality:
Type: Specify Type II or Type III based on your performance needs.
Thickness: Define the required coating thickness in microns or mils.
Color: Provide a RAL or Pantone number for color matching.
Corrosion Resistance: Often specified by hours of resistance in a salt spray test (e.g., ASTM B117).
Seal Quality: A proper seal is critical for performance and can be verified by an acid dissolution test.
Partner with a Pro for Your Batch Production
Choosing the right anodizing type and specification is critical for the performance and longevity of your components. As a specialized factory in CNC machining and surface treatment, we provide a seamless onestop solution. We expertly machine your aluminum parts and apply the precise anodizing finish they require, ensuring every batch meets the highest standards for durability, functionality, and visual appeal. Let us help you optimize your designs for superior results.