Metal surface treatment, ten methods, see how many you know?

Surface treatment is to form a surface layer with one or more particular properties on the material’s surface by physical or chemical methods. Surface treatment can improve product appearance, texture, function, and other aspects of performance.

1. Anodizing

It is mainly the anodic oxidation of aluminum, which uses the principle of electrochemistry to form a layer of Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloys. This oxide film layer has unique properties such as protection, decoration, insulation and wear resistance. Anodized gold CNC turning part

Process flow:
Monochrome, gradient color: polishing/sandblasting/drawing→degreasing→anodizing→neutralizing→dyeing→sealing→drying
Two-color:
①Polishing / sandblasting / wire drawing → degreasing → masking → anodizing 1 → anodizing 2 → sealing → drying
②Polishing / sandblasting / wire drawing → degreasing → anodizing 1 → laser engraving → anodizing 2 → sealing → drying

Technical Features:
1. Increase strength
2. Realize any color except white
3. Achieve nickel-free sealing and meet the requirements of Europe, the United States and other countries for nickel-free
Technical difficulties and key points for improvement: the yield level of anodizing is related to the cost of the final product. The key to improving the oxidation yield is the appropriate amount of oxidant, appropriate temperature and current density, which requires structural component manufacturers to continue to explore in the production process , seek a breakthrough. (We recommend that you pay attention to the “Mechanical Engineer” public account, and master the knowledge of dry goods and industry information as soon as possible)
Product recommendation: E+G arc handle, made of anodized material, environmentally friendly and durable. CNC machining stainless steel.

2. Electrophoresis

Used in stainless steel, aluminum alloy, etc., it can make the product show various colors, maintain the metallic luster, and at the same time enhance the surface performance, with good anti-corrosion performance.
Process flow: pretreatment→electrophoresis→drying

advantage:
1. Rich colors;
2. No metal texture, can cooperate with sandblasting, polishing, wire drawing, etc.;
3. Processing in liquid environment can realize surface treatment of complex structures;
4. The technology is mature and can be mass-produced.
Disadvantages: The ability to cover defects is general, and the electrophoresis of die castings requires higher pretreatment.

3. Micro-arc oxidation

The process of applying a high voltage in an electrolyte solution (usually a weak alkaline solution) to generate a ceramic surface film layer, which is the result of the synergistic effect of physical discharge and electrochemical oxidation.

Process flow: pretreatment → hot water washing → MAO → drying
advantage:
1. Ceramic texture, dull appearance, no high-gloss products, delicate hand feeling, anti-fingerprint;
2. Wide range of substrates: Al, Ti, Zn, Zr, Mg, Nb, and their alloys, etc.;
3. The pretreatment is simple; the product has excellent corrosion and weather resistance and good heat dissipation performance.
Disadvantages: At present, the color is limited; only black and gray are more mature, and bright colors are currently difficult to achieve; the cost is mainly affected by high power consumption, and it is one of the highest costs in surface treatment.

4. PVD vacuum plating

The full name is physical vapor deposition, an industrial manufacturing process mainly using physical processes to deposit thin films. CNC machining part

Process flow: pre-PVD cleaning → vacuuming in the furnace → target washing and ion cleaning → coating → coating completion, cooling out of the furnace → post-processing (polishing, AFP) (We recommend you pay attention to the “Mechanical Engineer” official account, the first time to grasp the dry goods knowledge, industry information)
Technical features: PVD (Physical Vapor Deposition, Physical Vapor Deposition) can coat metal surfaces with high hard plating and wear resistance cermet decorative coating.

5. Electroplating

It is a technology that uses electrolysis to attach a layer of metal film to the surface of the metal to prevent corrosion, improve wear resistance, electrical conductivity, reflectivity, and enhance aesthetics.
Process flow: pretreatment → cyanide-free alkali copper → cyanide-free cupronickel tin → chrome plating

Advantage:
1. The coating has a high gloss and high-quality metal appearance;
2. The base material is SUS, Al, Zn, Mg, etc.; the cost is lower than PVD.
Disadvantages: poor environmental protection and high risk of environmental pollution.

6. Powder coating

The powder coating is sprayed onto the surface of the workpiece by powder spraying equipment (electrostatic spraying machine). Under static electricity, the powder will be uniformly adsorbed on the surface of the workpiece to form a powder coating. It cures flat and becomes a final coating with various effects (different kinds of effects for powder coatings).
Technological process: upper part→electrostatic dust removal→spraying→low temperature leveling→baking

Advantage:
1. Rich colors, high gloss and matte optional;
2. Low cost, suitable for building furniture products and shells of heat sinks, etc.;
3. High utilization rate, 100% utilization, environmental protection;
4. Strong ability to cover defects; 5. It can imitate the wood grain effect.
Disadvantages: Currently used in electronic products less.

7. Metal wire drawing

It is a surface treatment method that forms lines on the surface of the workpiece by grinding the product, which has a decorative effect. The different lines, after drawing, can be divided into straight line drawings, random patterns, corrugated patterns, and swirl patterns.
Technical features: The wire drawing treatment can give the metal surface a non-mirror-like metallic luster, and the wire drawing treatment can also eliminate the subtle defects on the metal surface.
Product recommendation: LAMP handle, Zwei L treatment, using excellent grinding technology to show the taste.

8. Sandblasting

It is a process in which compressed air is used as power to form a high-speed spray beam to spray the spray material on the surface of the workpiece to be treated at high speed so that the appearance or shape of the outer surface of the workpiece surface changes, and a certain degree of cleanliness and different roughness are obtained.
Technical Features:
1. To achieve different reflective or matt.
2. It can clean the tiny burrs on the surface of the workpiece and make the surface of the workpiece smoother, eliminating the harm of burrs and improving the grade of the workpiece.
3. Clear the residual dirt left in the pretreatment, improve the smoothness of the workpiece, make the workpiece reveal a uniform and consistent metal color, and make the appearance of the workpiece more beautiful and beautiful. (We recommend that you pay attention to the “Mechanical Engineer” public account and master the knowledge of dry goods and industry information as soon as possible)
Product recommendation: E+G classic bridge handle, sandblasted surface, high-end atmosphere.

9. Polishing

Finish the workpiece surface using flexible polishing tools, air abrasive particle, ands other polishing media. For different polishing processes, such as rough polishing (basic polishing process), medium polishing (finishing process), and fine polishing (glazing process), selecting the appropriate polishing wheel can achieve the best polishing effect and improve polishing efficiency.

Technical features: Improve the workpiece’s dimensional or geometric shape accuracy, get a smooth surface or mirror gloss, and eliminate gloss.
Product recommendation: E+G long handle, polished surface, simple and elegant

10. Etching

Usually referred to as etching, also known as photochemical etching, it relates to the removal of the protective film in the area to be etched after exposure to plate making and development and contact with the chemical solution during etching to achieve the effect of dissolution and corrosion, forming concave-convex or hollow molding effect.
Process flow:
Exposure method: The project prepares the size of the material according to the graphic – material preparation – material cleaning – drying → film or coating → drying → exposure → development → drying – etching → stripping → OK
Screen printing method: cutting material → cleaning plate (stainless steel and other metal materials) → screen printing → etching → stripping → OK
Advantage:
1. It can carry out micro-processing of metal surfaces;
2. Give special effects to the metal surface;
Disadvantages: Most corrosive liquids (acids, alkalis, etc.) used in etching harm the environment.

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