Guide to Metal Surface Finishing: Everything you Need to Know

The metal surface finishing of components is a crucial stage of the manufacturing process. A high-quality metal surface finish can improve the performance of even the best-finished components. Obtaining the proper surface finish for a metal part improves its aesthetics and increases its durability.

Nowadays, numerous surface finishes can be imparted to metals, and you must be thorough with the various finishes available. So, here is an extensive guide that covers several prominent metal surface finishing techniques to help you boost product quality and reduce manufacturing bottlenecks without compromising precision engineering standards. Let’s dig deeper.

Different Types of Metal Surface Finishes

  • Anodizing

It’s an electrochemical method that aids in developing a long-lasting, elegant, and highly corrosion-resistant anodic oxide finish. Manufacturers achieve this finish by submerging the metal in an acidic electrolytic solution and then passing an electric current through the solution. The aluminum serves as the anode, while a cathode is installed within the anodizing tank.

As a result, the oxygen ions in the electrolyte react with the aluminum atoms on the workpiece surface, forming an anodic oxide. It implies that anodizing is a process where the metal substrate gets oxidized in a very controlled manner. It works well on other nonferrous metals like titanium and magnesium, but aluminum is where it really excels.

  • Powder Coating

In this technique, a dry powder gets deposited electrically onto a metal surface. After electrostatic powder deposition, the machinist places the metal in an oven to promote chemical reaction and improve the powder’s adhesion to the metal surface. The defense department, the automobile sector, and the tool manufacturing business extensively use this metal finishing technique.

  • Polishing

In these operations, abrasives are used to smooth the surface of machined metals. When coupled with felt or leather wheels, these abrasive powders buff and polish metal surfaces to the desired degree.

Polishing metal is a common manufacturing process, and it can either be done by hand or by machine with the help of robotic polishing. Polishing not only smoothes off the material’s surface but also brings out its natural luster. Thus, polishing and buffing are mostly used to enhance the visual appeal of a desktop CNC mill’s machined part.

  • Grinding

It is a standard machining operation that tends to eradicate imperfections on a metal surface. Machinists utilize this procedure after production is complete but before applying any coatings. The grinding wheel or grinder is a hand-held machine used to assist in smoothening the metal’s surface. Aluminum, cast iron, mild steel, and stainless steel are just a few examples of metals that undergo the grinding procedure regularly.

  • Brushing

Metal machined components benefit greatly from a brushing finish because it generates a consistent surface texture and enhances the exterior. To meet these demands, it frequently uses wire brushes or abrasive belts. However, the end outcome could differ from one manufacturer to the next, depending on how they implement the process. For instance, surface edges could get softened by brushing or belting in a single direction. Wire brushing, on the contrary, is used to get rid of welding slags. In addition to preparing metal for subsequent cleansing, plating, or coating processes, it also gets rid of any grit and scale that could be there.

Crucial Factors to Consider While Selecting a Metal Surface Finishing Process

Selecting appropriate metal surface finishes is simple so long as specific criteria are taken into account. Among these are the following-

  • Speed

Time frames vary according to the type of metal surface finish applied. There are quick ones, and there are slow ones. Thus, when you have a project due, think about how long it will take you to complete it. Think about how long it will take to finish the metal in each available option. If time is of the essence and you need to get something done, one option is to use a surface finish that can be processed rapidly.

  • Material

Not every metal can have its surface finished in the same way. So, you need to consider the material your workpiece is composed of and select a suitable surface finishing process for that material. For instance, applying a powerful abrasive technique may cause damage to softer materials. However, some materials are durable, and a gentle stroke will not yield the desired result in terms of finishing.

  • Budget

If you’re working with metal, you might have discovered the ideal finishing method, but the question here is whether you can afford it. Your final decision on the finishing process will be based primarily on your available funds. Ideally, you should select one that fits your budget without sacrificing quality. The overall profitability levels of your business could get adversely impacted if the product has pricey finishes.


The metal surface finishing process holds immense significance when it comes to the durability, quality, and functionality of a finished metal component. Therefore, all viable solutions should be considered carefully to guarantee the finished product will serve its purpose for as long as it is needed.

About the Author:

Peter Jacobs

Peter Jacobs is the Senior Director of Marketing at CNC Masters. He is actively involved in manufacturing processes and regularly contributes his insights to various blogs on CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general.

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