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Manufacturing Guide for Sheet Metal Surface Finishing

Views: 0     Author: Site Editor     Publish Time: 2023-03-08      Origin: Site


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Sheet metal manufacturing stands out as a versatile and cost-efficient approach for crafting metal components. However, to optimize physical and aesthetic attributes, additional post-processing or finishing becomes essential after employing techniques like forming, stamping, bending, and cutting. Notably, aluminum sheet metal boasts durability and corrosion resistance. This article delves into common high-quality sheet metal finishing options, offering insights into selecting the most suitable finishing technique. Let's delve into it!

Table of Contents:

Sheet Metal Finishing

Tips for Choosing the Right Sheet Metal Finishing Technique


Meet Your Sheet Metal Fabrication and Finishing Needs with ZONZE

In this section, we'll explore typical finishing options for sheet metal manufacturing parts. While the list provided isn't exhaustive, ZONZE is here to provide comprehensive assistance tailored to your specific fabrication and finishing requirements.

Standard/As-Machined Surface Finish


A standard finish entails leaving the final part without any additional surface treatment. This approach is typically adopted when the base material satisfies the requirements of the application environment. For instance, parts made from 316 stainless steel for use in corrosive settings often forego additional finishing, except for pickling and passivation, as stainless steel inherently offers excellent corrosion resistance. Moreover, in certain cases, the natural aesthetics of the parts are deemed appealing, further justifying the omission of finishing processes.



Electroplating, also referred to as electrodeposition, stands as a widely employed method for finishing metal sheets. This process involves applying a thin layer of sacrificial metal onto the surface of sheet metal components. Achieving this involves positioning the sacrificial metal on the anode within an electrolyte solution, while the metal sheet component is positioned on the cathode. Through the application of an electrical current, these two metals undergo a chemical bonding process.

Diverse electroplating materials are available, each offering distinct performance attributes. At Runsom Precision, our electroplating services encompass nickel, tin, and chemical nickel-plated sheet metal components. Notably, it's essential to consider the tolerances of the original parts to accommodate the thickness of the final plating.

Electroplating serves to enhance the conductivity of components and bolster their radiation resistance, rendering it a favored technique for crafting radiation shields.



Sandblasting serves as a prevalent finishing technique in sheet metal fabrication, employing abrasive media such as sand or glass beads to refine surfaces. Unlike conventional sandblasting, this method employs lower air pressure, resulting in minimal material removal and a smoother surface. It excels in eliminating tool marks and imperfections, ensuring a consistent surface finish. Moreover, sandblasting effectively obscures grain direction on metal sheets, ideal for maintaining uniformity in laser-cut metal parts.

Bead blasting, known for its ability to deliver a matte finish, emerges as a preferred surface treatment for aluminum sheet metal parts that demand high visual quality. Its aesthetic appeal makes it a popular choice, complementing the requirements of various applications. Sandblasting can be seamlessly integrated with other finishing techniques, offering versatility and adaptability to meet diverse aesthetic and functional demands.



Anodizing stands out as a prominent finishing technique tailored for aluminum and titanium sheet metal components. It entails the creation of a corrosion-resistant layer through electrochemical processes. During anodization, sheet metal parts are immersed in an acidic electrolyte and subjected to electrical current, leading to the formation of a cohesive anodized layer across the surface.

Anodizing can be categorized into three main types, each with subcategories:

Type I anodizing, less prevalent but crucial in aerospace, yields thin yet highly corrosion-resistant coatings. Type II, further categorized into Class 1 and Class 2, generates a thin oxide layer dyed in multiple colors, blending aesthetics with corrosion resilience. Type III, offering thicker coatings, notably enhances wear resistance, available in clear or black variants. Anodizing, with its diverse surface finishes and hues, finds extensive utility in fabricating mechanical parts, precision instruments, aircraft components, and automotive accessories, among other applications.

Chemical Nickel Plating


Chemical nickel plating stands apart from conventional electroplating techniques by relying on chemical processes rather than electrochemical reactions for metal deposition. This method applies nickel coatings with diverse phosphorus levels, augmenting corrosion resistance while tempering hardness and wear resistance. Notably, its uniform coverage extends even to intricate or inaccessible surfaces, making it ideal for complex sheet metal components. Moreover, chemical nickel plating accommodates a broader spectrum of metal substrates and can undergo heat treatment to bolster mechanical attributes.

Powder Coating


Powder coating stands out among sheet metal finishing techniques for its vast array of color choices and versatility in achieving diverse surface textures and finishes, including gloss, semi-gloss, metallic, and flat. This method involves applying powder paint onto the metal surface, followed by baking to fuse the paint, forming a resilient, corrosion-resistant, and wear-resistant layer. Consequently, powder coating surpasses traditional painting methods by providing a durable exterior layer for sheet metal components.


Electrophoretic coating, also known as e-coating, employs electrical currents to apply paint onto metal surfaces, enhancing product durability and corrosion resistance. Unlike powder coating, e-coating immerses sheet metal parts in a chemical solution containing epoxy resin, slurry, and deionized water. Through the application of a specific voltage, the coating uniformly adheres to the metal, ensuring precise and consistent thickness down to micrometer-level accuracy.

Gold and Silver Plating

Applying gold and silver coatings to metal parts involves the use of electroplating processes.

Electrophoretic Coating (E-Coating)


Gold possesses exceptional conductivity and resists corrosion, tarnishing, and oxidation, making it an optimal choice for coating electrical contacts. Its superior solderability further enhances its suitability for electronic components. Gold plating is available in diverse types, reflecting the gold's purity, and classes, denoting the thickness of the coating.


Silver plating offers several advantages compared to gold plating. It boasts superior electrical properties and is a more cost-effective option. Nonetheless, during the application of this method, sheet metal parts may be vulnerable to oxidation, potentially diminishing their conductivity over time.

Chemical Film Coating


Chemical film coatings, also known as conversion coatings, serve as sealant coatings, offering corrosion resistance without adding wear resistance. However, they excel in preserving conductivity and facilitating the adhesion of paints and powder coatings. Moreover, these coatings can be layered with an anodized finish. Here are various classifications of chemical film coatings:

Type 1: Although less common due to its use of hexavalent chromium, it produces a gold or brown coating. 

Type 2: Utilizing zirconium, titanium, or trivalent chromium, it creates a clear coating, often employed in aerospace and military applications. 

Class 1A: This type enhances substrate corrosion resistance and serves as a primer for decorative or corrosion-resistant coatings, typically thicker than Class 3 coatings. 

Class 3: Developed to offer superior corrosion resistance while maintaining conductivity.


Passivation is a surface finishing process that involves immersing stainless steel or other alloys into an acid solution to remove free iron from the surface, resulting in "passivating" the metal.


Residual elements on metal surfaces can affect their reactivity, leading to improved rust and corrosion resistance. After processes such as welding, cutting, or grinding, foreign substances may alter the metal's surface, making passivation a recommended step. Passivation significantly enhances metal corrosion resistance. However, thorough cleaning before passivation is crucial for its success; otherwise, it may prove ineffective. Surface damage from cutting, grinding, or welding processes can sometimes induce corrosion, making passivation necessary. Reapplication of the process might be needed during the part's service life.

Tips for Choosing the Right Sheet Metal Finishing Technique

Merely understanding sheet metal surface finishing is insufficient; knowing how to choose the appropriate finishing process is equally vital. Several factors should be considered to ensure the selection of the best sheet metal finishing solution, including cost. It's crucial to evaluate all available pricing options before making a decision. For instance, while anodizing may offer desirable results, it can also be costly. Thus, striking a balance between cost-effectiveness and quality is imperative for achieving optimal outcomes.

Type of Sheet Metal Material

The sheet metal finishing methods available vary depending on the type of material employed. Certain finishing processes are tailored to specific materials; for instance, anodizing is exclusively suitable for aluminum and titanium. Additionally, it's crucial to acknowledge that materials exhibit varying hardness levels. Employing abrasive finishing techniques such as sandblasting on soft metal sheets can potentially result in component damage. Thus, careful consideration of material properties is essential when deciding on the appropriate finishing approach.


Sheet metal finishing serves as an excellent option for improving both the visual appeal and functional attributes of components. Each of the aforementioned finishing techniques caters to aesthetic enhancements to different extents and also provides diverse functional benefits. For instance, while finishing stainless steel sheets might primarily aim at enhancing aesthetics, finishing aluminum sheet metal often serves both aesthetic and functional objectives.

Coating Thickness

Considering the thickness of the coating is crucial when selecting sheet metal finishing methods. Each of the mentioned finishing techniques exhibits a dependence on coating thickness. Here are examples of coating thickness ranges for the aforementioned finishes:

  • Anodizing can yield thicknesses ranging from 0.5 µm to 150 µm, depending on the type.

  • Electroplating generally results in thicknesses ranging from 5 µm to 25 µm.

  • Powder coating typically achieves thicknesses ranging from 35 µm to 200 µm.

Lead Time

Speed is paramount when choosing sheet metal finishing techniques, especially when facing tight deadlines. Prioritize fast solutions to meet these deadlines. However, remember to strike a balance with quality, as achieving higher quality may entail allocating more production time.


Sheet metal fabrication offers a range of surface treatments, each with distinct visual effects and functional benefits like enhanced aesthetics, durability, and corrosion resistance. However, these treatments vary in characteristics, performance, and costs, and their suitability depends on the metal and its application. Therefore, it's crucial to carefully assess the application requirements when choosing the ideal surface treatment. This article explored ten top-notch finishing processes and considerations to aid in selecting the most suitable one for your project.

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