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Metal cnc finishing process and its working principle

Metal finishing, or metal finishing, is the process of altering the surface of an object using different techniques to improve appearance and performance, such as corrosion resistance, tarnish resistance, chemical resistance, abrasion resistance and hardness, modification of electrical conductivity, removal of Burrs or apply specific colors to machined parts.

It is usually done by adding a metallic or non-metallic coating to the exterior of the metallic workpiece while also cleaning the part. Metal surface finishing service, commonly used in CNC machining parts of aluminum, stainless steel, brass and other materials.

The role of metal surface treatment can be summarized as follows:

– Improve appearance

– Add specific beautiful colors

– Change gloss

– Enhanced chemical resistance

– Increased wear resistance

– Limit corrosion effects

– Reduce friction

– Removal of surface defects

– Cleaning parts

– As a primer

– Resize

Different Types of Metal Finishing - Kyowa Provides Metal Finishing Services

1. Anodizing

The electrolytic passivation process that forms a thin layer of metal oxide on the surface of the part to increase the thickness of the natural oxide layer, protect the metal, increase various colors, and improve corrosion resistance and wear resistance. Aluminum is the most widely anodized material, and the benefits of anodizing aluminum parts are well known, but many other metals can also undergo the process, such as stainless steel, copper, titanium, zinc and magnesium.

2. Passivation

A common chemical surface treatment, primarily used on steel and stainless steel, that applies a thin layer of protective material to the casing to enhance corrosion resistance or reduce chemical reactivity. The passivation of stainless steel uses an acid solution to remove free iron and ferrous contaminants on the metal surface to prevent rust.

3. Electroplating

The process of using an electric current to reduce dissolved metal cations so that they form a thin, coherent metal coating on an electrode, thereby changing the properties of the metal surface or adding thickness to undersized parts.

4. Spraying

The process of spraying paint, pigment or color onto a solid surface as a colored protective layer, can be done on any shape of metal or non-metal CNC machined parts, usually applied to aluminum, stainless steel and steel alloy parts. The purpose is to improve the aesthetic appearance and prevent corrosion or oxidation.

5. Black oxide (thermal blackening)

Also known as blackening or gun bluing, this technique is a chemical process that creates a black conversion coating on stainless steel, copper and copper-based alloys, zinc, powdered metals, silver solder, and ferrous materials. Black oxide coatings can Improves corrosion resistance and minimizes light reflections.

6. Polishing

Polishing, also known as buffing, is a process of rubbing the surface of a part or using chemical action to produce a smooth and shiny surface, so that the surface has a significant specular reflection or reduces the diffuse reflection of some materials.

7. Powder coating

The process of placing functional and decorative finishes, applied as a free-flowing dry powder, applied electrostatically and then cured with heat to form a hard finish that is stronger than traditional paint. Key applications include household appliances, aluminum extrusions, drum hardware, automotive, motorcycle and bicycle parts.

8. Heat treatment

The process of using heating or cooling at extreme temperatures to bring metals to a certain state or to change certain properties. Heat treatment techniques include annealing, tempering, hardening, precipitation strengthening, tempering, carburizing, normalizing, and quenching.

9. Satin finish

Apply gloss between a dull matte finish for matte materials and a bright glossy finish for glossy finishes. The visual effect is related to the ambient lighting, and the satin metal finish is reflective, flat and shiny.

10. Sandblasting

Use sand blasting equipment such as air pressure system to push the abrasive stream composed of high-speed sand grains to the metal surface under high pressure, remove surface pollutants, clean metal or increase texture, and then change smoothness or surface roughness.

11. Conversion coating

Also known as chromating, coatings are used on metals that are converted by chemical or electrochemical processes into a protective layer, primarily as a corrosion inhibitor, decorative finish, or to maintain electrical conductivity.

Choose the best metal finishing process

After browsing the list of metal finishing surface preparation services, select a process based on basic considerations such as production time, cost-effectiveness, part tolerance, durability and application. High-tolerance CNC milling, secondary metal surface finishing is not recommended because the treatment may alter the dimensions of the finished part by removing or adding small amounts of material.