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The most complete metal surface treatment summary in history

Oct 12-2020     Views: 131


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


1. Anodizing


It is mainly the anodization of aluminum, which uses electrochemical principles to form a layer of Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloy. This oxide film has special characteristics such as protection, decoration, insulation, and wear resistance.


Process flow:


Single color, gradient color:


Polishing / sandblasting / wire drawing → degreasing → anodizing → neutralization → dyeing → sealing → drying


Two colors:


①Polishing/sandblasting/wire drawing→degreasing→masking→anodic oxidation 1→anodic oxidation 2→sealing→drying


②Polishing/sand blasting/wire drawing → degreasing → anodizing 1 → laser carving → anodizing 2 → sealing → drying


Technical features:


1. Improve strength


2. Realize any color except white


3. Achieve nickel-free sealing and meet the requirements for nickel-free in Europe, the United States and other countries


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 yield of oxidation is the appropriate amount of oxidant, appropriate temperature and current density. This requires structural component manufacturers to continuously explore and seek breakthroughs in the production process.


Products Recommended:


The E+G arc handle is made of anodized material, which is environmentally friendly and durable.


2. Electrophoresis


Used in stainless steel, aluminum alloy, etc., it can make the product show a variety of colors, and maintain the metallic luster, at the same time enhance the surface performance, with better anti-corrosion performance.


Process flow:


Pretreatment → electrophoresis → drying


Advantage:


1. Rich colors;


2. No metal texture, can be used with sandblasting, polishing, wire drawing, etc.;


3. Processing in a liquid environment can achieve surface treatment of complex structures;


4. Mature technology and mass production.


Disadvantages:


The ability to conceal defects is average, and electrophoresis for 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 ceramicized surface film. This process is the result of the synergistic effect of physical discharge and electrochemical oxidation.


Process flow:


Pre-treatment → hot water washing → MAO → drying


Advantage:


1. Ceramic texture, dull appearance, no high-gloss products, fine touch, anti-fingerprint;


2. Wide range of base materials: Al, Ti, Zn, Zr, Mg, Nb, and their alloys, etc.;


3. Simple pretreatment, excellent corrosion resistance and weather resistance, and good heat dissipation performance.


Disadvantages:


At present, the color is limited. Only black and gray are more mature. Bright colors are currently difficult to achieve; the cost is mainly affected by high power consumption, and it is one of the most expensive surface treatments.


4. PVD vacuum plating


The full name is physical vapor deposition, which is an industrial manufacturing process that mainly uses physical processes to deposit thin films.


Process flow:


Cleaning before PVD → vacuuming in the furnace → cleaning target and ion cleaning → coating → coating finished, cooling out of the furnace → post-processing (polishing, AFP)


Technical features:


PVD (Physical Vapor Deposition, physical vapor deposition) can be coated on the metal surface with high-hardness, high wear resistance cermet decorative coating


5. Electroplating


It is a technology that uses electrolysis to attach a 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 copper-nickel alloy tin→Chrome plating


Advantage:


1. The coating has high gloss and high-quality metal appearance;


2. The base material is SUS, Al, Zn, Mg, etc.; the cost is relatively low compared to PVD.


Disadvantages:


Environmental protection is poor and environmental pollution risks are greater.


6. Powder coating


Powder coating equipment (electrostatic spraying machine) is used to spray powder coating on the surface of the workpiece. Under the action of static electricity, the powder will be uniformly absorbed on the surface of the workpiece to form a powder coating; the powder coating flows through high temperature baking. It is cured evenly and becomes the final coating with different effects (different types of powder coating effects).


Process flow:


Upper part → electrostatic dust removal → spraying → low temperature leveling → baking


Advantage:


1. Rich colors, high gloss and matte finish are optional;


2. The cost is low, and it is suitable for the shell of building furniture products and heat sinks;


3. High utilization rate, 100% utilization, environmental protection;


4. Strong ability to cover defects; 


5. Wood grain effect can be imitated.


Disadvantages:


Currently used in electronic products is relatively small.


7. Metal wire drawing


It is a surface treatment method that forms lines on the surface of the workpiece by grinding products to achieve a decorative effect. According to the different lines after drawing, it can be divided into: straight line drawing, random line drawing, corrugation, and swirling.


Technical features:


The wire drawing treatment can make the metal surface obtain a non-mirror-like metallic luster, and the wire drawing treatment can also eliminate the fine defects on the metal surface.


Products Recommended:


LAMP handle, Zwei L treatment, using excellent grinding technology, highlighting the taste.


8. Sandblasting


It is a process that uses compressed air as the power to form a high-speed jet beam to spray the spray material on the surface of the workpiece to be treated at a high speed, so that the appearance or shape of the outer surface of the workpiece surface is changed, and a certain degree of cleanliness and different roughness are obtained.


Technical features:


1. Realize different reflective or matt.


2. It can clean up the tiny burrs on the surface of the workpiece and make the surface of the workpiece smoother, eliminating the hazards of burrs and improving the quality of the workpiece.


3. Clear the residue left during the pretreatment, improve the finish of the workpiece, and make the workpiece show a uniform and consistent metal color, making the appearance of the workpiece more beautiful and attractive.


Products Recommended:


E+G classic bridge handle, sandblasted surface, high-end atmosphere and class.


9. Polishing


Use flexible polishing tools and abrasive particles or other polishing media to modify the surface of the workpiece. For different polishing processes: rough polishing (basic polishing process), medium polishing (finishing process) and fine polishing (coating process), choosing a suitable polishing wheel can achieve the best polishing effect and improve polishing efficiency.


Technical features:


Improve the dimensional accuracy or geometric shape accuracy of the workpiece, obtain a smooth surface or mirror gloss, and also eliminate the gloss.


Products Recommended:


E+G long handle, polished surface, simple and generous


10. Etching


Generally referred to as etching is also called photochemical etching, which refers to the removal of the protective film of the area to be etched after exposure, plate making and development, and contact with chemical solutions during etching to achieve the effect of dissolving and corroding, forming unevenness or hollowing out.


Exposure method:


The project opens up 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 → cleaning the plate (stainless steel and other metal materials) → screen printing → etching → stripping → OK


Advantage:


1. It can perform fine processing of metal surface;


2. Give special effects to the metal surface;


Disadvantages:


Most of the corrosive liquids (acids, alkalis, etc.) used in etching are harmful to the environment.


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