It's a CNC mill work for aluminium anodizing parts. After cnc machining is complete the part is anodized blue. Unlike most other finishes, anodizing preserves the natural luster, texture, and beauty of the metal itself. The anodized coating is hard, durable, will never peel, and, under normal conditions, will never wear through. Anodizing is a process for finishing aluminum alloys that employs electrolytic oxidation of the aluminum surface to produce a protective oxide coating. The anodic coating consists of hydrated aluminum oxide and is considered resistant to corrosion and abrasion. Conventional coatings are 0.1 to 1.0 mil thick and are essentially transparent but they may be colored like sample above. Why Anodize Precision Machined Components? Anodizing precision machined components provides a reliable and relatively inexpensive means of improving the wear resistance, and coloring aluminum and other nonferrous metals. First developed in the 1920s, this electrochemical process revolutionized numerous industries with a need for lightweight, strong, corrosion-resistant aluminum extrusions for window frames, decorative exterior panels and many other architectural elements. Today it protects satellites, skyscraper facades and components for a wide variety of industries from aerospace to medical and is one of the most efficient ways to make aluminum parts that last and require little maintenance.