CNC Lathing Parts with Black Oxide Treatment

KYLT CNC Machining Services for Custom Parts
On-demand CNC machining services for Rapid Prototypes and production parts in metal and Plastic materials.

* CNC Milling, CNC Turning
* Rapid Prototype & Mass Production
* Machined Parts as fast as 1 day
* Aluminum, Magnesium, Steel, Polymers & More

Free Quote Service: cnkylt@aliyun.com

CNC lathing parts with black treatment typically refers to a surface finishing process called "black oxide" or "blackening" , which is applied to machined metal parts to provide a uniform black finish, mild corrosion resistance, and a professional appearance without significantly altering the part's dimensions.

What is Black Oxide Treatment?

Black oxide is a conversion coating process. It doesn't add a significant layer of material onto the part. Instead, it chemically reacts with the metal surface itself to form a protective layer of magnetite (Fe₃O₄), which is black in color. This process is also known as "blackening" .

The Black Oxide Process

The process generally involves several key steps to ensure a high-quality, durable finish:
Cleaning: The CNC-turned parts are thoroughly cleaned using alkaline solutions to remove all dirt, grease, oil, and other contaminants from the machining process.
Rinsing: The parts are rinsed with water (often distilled water) to remove the cleaning solution.
Acid Pickling (if needed): If the parts have any rust or scale, they are immersed in an acid bath to remove it.
Black Oxide Bath: The clean parts are immersed in a heated alkaline salt solution, typically containing sodium hydroxide, nitrates, and nitrites. The temperature is carefully controlled, usually around 140-146°C (285-305°F) for the hot process. This chemical reaction converts the iron on the surface into the black magnetite layer.
Post-Treatment (Sealing): After the oxidation bath, the parts are rinsed again. Because the black oxide layer is porous, it must be sealed to provide any meaningful corrosion resistance. This is most commonly done by impregnating the surface with oil, which also gives the part a slight gloss. Wax or lacquer can also be used for a matte finish or faster drying.

Free quote for CNC machining service: cnkylt@aliyun.com