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The Difference Between Sandblasting and Anodizing: A Comprehensive Guide

649   |   Published by VMT at Aug 17 2021



After the aluminum profile is extruded and formed, it is processed by numerical control. In order to achieve the durability and aesthetics of the parts, the surface treatment will be performed after the processing is fully inspected. Common surface treatments for parts include anodic oxidation, sandblasting oxidation, electrostatic powder spraying and so on.


It is suitable for a variety of materials, different materials, and different surface treatment methods. VMT will choose the appropriate surface treatment for you according to the purpose and material of your processed parts. Each processing technology has its advantages and disadvantages, so what is the difference between the two surface treatment processes of anodizing and sandblasting?




What is anodizing?


Anodizing is an electrolytic process that deposits a chemically stable oxide layer on the surface of aluminum parts. The resulting oxide film is thicker and stronger than the natural oxide coating of aluminum. It is hard, porous, and transparent, and is an indispensable part of the metal surface, so it will not peel or peel off.





Anodizing is an electrochemical process that enhances the surface of metals, particularly aluminum and its alloys. It involves creating a controlled oxide layer on the metal surface, which provides increased corrosion resistance, improved durability, and the option to add color.





In the anodizing process, the metal is immersed in an electrolyte bath and serves as the anode. An electric current is applied, which causes oxygen ions to combine with the metal surface, forming a stable oxide layer. This oxide layer can be further treated to achieve specific properties or coloration.





Anodizing is widely used in industries that require lightweight and corrosion-resistant materials. It is commonly applied to aluminum components in the automotive, aerospace, and architectural sectors. Anodized surfaces are also found in consumer electronics and decorative items.




Benefits of Anodizing



Enhanced corrosion resistance


Anodizing significantly improves the corrosion resistance of metals, particularly aluminum. The anodized layer acts as a barrier, protecting the underlying material from environmental factors and extending its lifespan.



Improved aesthetics


Anodizing provides a wide range of color options, allowing manufacturers to achieve desired aesthetics. The process can produce vibrant, fade-resistant colors that integrate seamlessly with the metal substrate.



Electrical insulation


The anodized oxide layer on aluminum provides electrical insulation properties, making it suitable for applications where electrical conductivity needs to be controlled or eliminated.





Anodized surfaces are highly durable and resistant to wear, making them ideal for components exposed to harsh environments or frequent handling.




Limitations of Anodizing



Limited color options


Compared to other surface treatment methods, anodizing offers a relatively limited range of color options. The color variations are achieved through different dyeing techniques, but the final colors may still be somewhat restricted.



Material restrictions


Anodizing is primarily applicable to aluminum and its alloys. Other metals, such as steel or copper, have different properties and require alternative surface treatment methods.




The Difference Between Sandblasting and Anodic Oxidation-1




What is sandblasting?


The process of using the impact of high-speed sand flow to clean and roughen the surface of parts. Compressed air is used as the power to form a high-speed jet beam to spray the spray material (copper ore, quartz sand, emery sand, iron sand, Hainan sand) on the surface of the parts to be treated at a high speed, so that the appearance or shape of the part surface will change.


The impact and cutting action on the surface of the part can make the surface of the part obtain cleanliness and different roughness, improve the mechanical properties of the surface of the part, improve the fatigue resistance of the part, and increase the adhesion between the part and the coating. , It prolongs the durability of the coating film, and is also conducive to the leveling and decoration of the coating.







Sandblasting, also known as abrasive blasting, is a surface treatment method that involves propelling abrasive particles at high speed to clean, roughen, or shape the surface of a material. The process uses compressed air or steam to propel abrasive materials, such as sand, glass beads, or aluminum oxide, onto the surface.





Sandblasting is typically carried out in an enclosed chamber to prevent the dispersion of abrasive particles. The compressed air or steam creates a high-velocity stream of abrasive materials, which forcefully impact the surface, effectively removing impurities, paint, rust, and other unwanted coatings.





Sandblasting finds applications in various industries. It is commonly used for surface preparation before painting or coating applications. Additionally, sandblasting is utilized for cleaning large structures, such as bridges or buildings, and for restoring and refurbishing surfaces.




Benefits of Sandblasting



Surface preparation


Sandblasting is highly effective in preparing surfaces for further treatment. By removing rust, old paint, and contaminants, it ensures proper adhesion of subsequent coatings or finishes.



Paint removal


Sandblasting is an efficient method for stripping paint from surfaces. It can remove multiple layers of paint without damaging the underlying material, making it ideal for refurbishment projects.



Rust and corrosion removal


The high-velocity impact of abrasive particles in sandblasting effectively eliminates rust and corrosion from metal surfaces, restoring their integrity and prolonging their lifespan.



Texturing and finishing


Sandblasting can create unique textures and finishes on various materials, providing aesthetic appeal or enhancing functional properties such as grip or light diffusion.




Limitations of Sandblasting



Environmental concerns


Traditional sandblasting methods generate a significant amount of dust and debris, which can be harmful to the environment and human health. However, modern sandblasting techniques employ alternative media and containment measures to mitigate these concerns.



Material damage


Some materials, such as soft metals or fragile substrates, may be susceptible to damage during the sandblasting process. Care must be taken to select appropriate abrasives and adjust blasting parameters accordingly.




The difference between sandblasting and Anodizing



(1) Processing technology:

Sand blasting relies on external force to spray sand to the surface of the parts to achieve passivation treatment, cleaning, decorative design and other practical effects. External force is called dry sand blasting when air is compressed, and wet sand blasting when it is water.


Anodizing generally refers to the oxidation of aluminum and aluminum alloy profiles in hydrochloric acid or other aqueous solutions, the parts are anodicized, and the aluminum alloy plate or graphite plate is connected to the negative electrode. Through the DC power supply, a porous structure, high strength, and dielectric can be obtained. Strong oxide film.





(2) The difference between sandblasting oxidation and anodic oxidation:



1. Different processing methods


Sandblasting of aluminum profiles is a physical treatment, and anodizing of aluminum profiles is a chemical treatment. Generally speaking, if the aluminum profile cannot be anti-corrosive after anodizing treatment, then it needs to be sandblasted and oxidized, and then sprayed, so that it can achieve the expected purpose.




2. Solve the difference in actual effect


Sandblasting and oxidation of aluminum profiles can be cleaned, polished, burrs, and the surface roughness can be changed to achieve practical decorative effects. Anodizing of aluminum profiles does not have this practical effect.




3. Different corrosion resistance


There is no protective layer on the sandblasted and oxidized surface of aluminum profiles, which cannot meet the requirements of corrosion resistance. The anodizing of aluminum profiles can meet the anti-corrosion requirements, and sandblasting must be done before anodizing.





Choosing Between Sandblasting and Anodizing




When faced with the decision of whether to sandblast or anodize a surface, several factors should be considered:



Surface type and condition


Sandblasting is particularly effective for cleaning and preparing surfaces with existing coatings, rust, or corrosion. Anodizing, on the other hand, is most suitable for aluminum surfaces and provides enhanced corrosion resistance.



Desired outcome


If the goal is to remove unwanted coatings, clean the surface, or create unique textures, sandblasting is the preferred option. Anodizing is chosen when corrosion resistance, durability, or aesthetics are the primary concerns.



Budget and time constraints


Sandblasting is generally a faster and more cost-effective process compared to anodizing. However, if the surface requires long-lasting protection or specific colors, anodizing may be the better choice despite the additional time and cost involved.





In conclusion


Sandblasting is to achieve the practical effects of passivation treatment, cleaning, decorative design, etc., while anodic oxidation is carried out in hydrochloric acid or other aqueous solutions. The two processes are different in method, effect and corrosiveness.


Sandblasting and anodizing are two distinct surface treatment methods, each with its own advantages and limitations. Sandblasting excels in surface preparation, paint removal, and rust/corrosion removal, while anodizing offers enhanced corrosion resistance, improved aesthetics, and durability. The choice between these methods depends on factors such as surface type, desired outcome, and budget constraints. By understanding the differences between sandblasting and anodizing, professionals can make informed decisions to achieve optimal surface treatment results.







Can I anodize a surface that has been sandblasted?

Yes, sandblasting can be performed as a surface preparation step before anodizing to ensure the removal of impurities and contaminants.


Is sandblasting suitable for delicate materials?

Sandblasting may not be suitable for fragile or soft materials, as it can cause damage. Alternative methods should be considered for such materials.


How long does the anodizing process take?

The duration of the anodizing process depends on various factors, including the desired thickness of the anodized layer. Typically, it can range from a few hours to several days.


What types of materials can be sandblasted?

Sandblasting is suitable for a wide range of materials, including metals, ceramics, glass, and certain plastics.


Can sandblasting remove all types of paint?

Sandblasting is highly effective in removing most types of paint, including oil-based, latex, and epoxy coatings.


Is anodizing a permanent process?

Yes, once anodized, the oxide layer formed on the metal surface is permanent and provides long-lasting protection.


Can anodizing prevent rust formation?

Anodizing significantly enhances the corrosion resistance of metals, including aluminum, thereby reducing the risk of rust formation.


Can I anodize CNC machining parts?

Yes, CNC machining parts made from aluminum or its alloys can undergo the anodizing process to improve their surface properties and aesthetics.






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