A finished metal part can have characteristic scratches on its surface from all the prototyping and fabrication techniques it has gone through. These scratches do not only leave undesirable aspects to its appearance but also expose the part to corrosion and rust.

In some designs, these scratches can be ignored because they are part of its features. In others, to be truly completed, the part has to undergo finishing services.

Here are some of the most common finishing techniques that you can use on metal parts.

1. Grinding and Milling

These two are known as abrasive techniques used to alter the surface appearance of a metal par. They are compatible with processes like mold-making because the shapes are precise. It can also be used for stock finishing metal items before applying decorative finishes. Between the two, grinding can provide a more precise result.

2. Electropolishing

This finishing technique is similar to electroplating as it uses electricity and chemicals while the object is submerged in an electrolyte bath. The bath solution works on the metal by removing the ions from the substrate and leaves a smooth surface,

3. Sandblasting and Shot Blasting

Another two abrasive methods used to finish a metal surface are sandblasting and shot blasting. The process involves propelling small and hard particles on the metal's surface to clean out the surfaces from grease, oil, and dirt.

4. Electroplating

Metal plating or electroplating is a more familiar type of metal finishing. It uses a metal substrate in a bath and passes a current through the metal.

This bath solution contains metal ions of the coating material. When the metal is submerged in the bath, it acts as a cathode because it has negatively charged ions. In some cases, the coating material is made from gold or silver but the most common are zinc, cadmium, chrome, or nickel.

Electroplating is versatile and you can use it for most metals. It offers a durable finish and improves the surface's rust resistance. It also has a nice-looking finish.

5. Galvanizing

This metal finishing technique adds a protective zinc coating to steel and iron substrates. It is used to protect the metal from corrosion as it seals the surface from moisture, water, and other elements. Galvanization is required by many industries including, automotive, construction, and agriculture.

6. Anodizing

Anodizing applies exclusively to aluminum. It involves immersing the finished part into an acid electrolyte bath, where an electric current passes through. The aluminum acts as an anode while the oxygen ions are released from the electrolyte combined with the aluminum atoms. Its effect on the surface renders the sheet metal resistant to abrasion and corrosion.

7. Polishing

Different polishing techniques can be used to remove the surface oxidation and enhance its appearance and at the same time prevent corrosion. In polishing, the results will depend on the grade of the abrasive.

8. Brushing

Brushing is a metal finishing technique that leaves metal substrates on the surface leaving a uniform finish with an abrasive belt or brush. It is a combination of buffing and grinding to smoothen out the surface and leaves metallic luster with a distinct pattern. The purpose of brushing is more decorative and it does not protect the surface from corrosion.

9. Painting

Painting is a low-cost way of protecting the metal's surface and gives it a decorative finish. Paints can offer heat-resistant and hardening qualities to the metal but they can be hard to apply uniformly. It also does not offer long-term protection.

10. Powder Coating

It is an alternative to painting and they share many common properties. However, powder coating is more durable, versatile, and has more advantages compared to liquid paint. It also achieves a more even coat and forms a hard outer shell over the surface.

The Best Metal Finish

Choosing the metal finishing service depends largely on its final application. While some techniques are good at protecting the surface from rust and corrosion like electroplating and galvanizing, others like brushing are meant to enhance its appearance. Choose a finishing service that will offer several advantages.