Choosing the Right Finish: Anodizing, Passivation, and Powder Coating for CNC Parts
Among the different manufacturing services offered at Craftcloud®, CNC machining enables you to mass produce models in a variety of solid and resistant materials. In addition to this, there are different post-processing techniques and finishes available that can further help you reach your goals.
Anodizing
Anodizing is an electrochemical process that converts a metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. This process is primarily compatible with non-ferrous metals, including aluminum alloys like 6061-T6, but also titanium and magnesium. Anodizing significantly increases wear resistance and allows for vibrant color dyeing while maintaining dimensional precision. However, it isn’t compatible with steel or stainless steel and can be more expensive than basic coatings due to the specialized chemical baths required. For steel parts, an alternative would be to consider zinc plating.
Passivation
Passivation is a chemical treatment for stainless steel that removes free iron from the surface to enhance the protective passive layer. This post-processing technique is specifically designed for stainless steel alloys to prevent premature corrosion. A major advantage of passivation is that it improves the lifespan and hygienic properties of medical or food-grade parts without changing the part’s dimensions or appearance. On the negative side, it provides no benefit to non-stainless steels or aluminum.
Powder Coating
Powder coating is a dry finishing process where a free-flowing, thermoplastic or thermoset powder is applied electrostatically to a part and then cured under heat to form a hard “skin.” It is compatible with a wide range of metals, including aluminum, steel, and stainless steel, making it a highly versatile industrial finish. The main advantages are its exceptional durability, impact resistance, and the ability to produce a totally smooth surface finish that hides machining marks. Conversely, disadvantages include a significant increase in part thickness that can ruin tight tolerances and the fact that it is difficult to touch up if the coating is chipped.
If you want to find out the price of each finish for your part(s), upload your model to Craftcloud® and get a quote in no time!