A metal part or product is only as good as its finish. It’s not as simple as slapping a coat of paint on a piece of metal. There are many impressive metal finishing techniques, and they all entail unique processes.
The most popular metal finishing techniques include powder coating and electropolishing. Conversion coating is also popular because it helps remove imperfections and make surfaces up to 50% smoother. Phosphate coating, anodizing, buff polishing, and sanding are also used for metal parts used in the automotive, construction, aerospace, and medical industries.
It’s essential to finish metal parts, especially when they’re going to be exposed to the elements. That’s because finishing techniques like powder coating and phosphate coating offer impressive corrosion resistance. Follow along as we explore the best metal finishing techniques and highlight their benefits.
8 Effective Metal Finishing Techniques
1. Powder Coating
Powder coating is one of the most common and popular techniques for finishing metal. Serving as a type of dry paint, powder coating involves an electrostatic process. Fabricators and engineers electrostatically charge powder to ensure they adhere to metal.
The process doesn’t add much thickness to a metal, which is a necessary benefit. Granted, it is sometimes thicker than paint, depending on the type of paint and how many coats you apply. However, powder coating is more durable than paint, which can chip and flake.
The coat stays and good shape and doesn’t require touch-ups or overly specific cleaning products. Powder coating is also a cost-effective option that can save time and money. The process is automated, which helps cut costs and ensures the finishing process goes quickly.
2. Electropolishing
Electropolishing is a popular finishing process because it can remove imperfections. Sometimes, fabricated metals come out with small peaks, valleys, and irregularities. This comes in handy when you work with small parts, such as screws and springs that must be perfect.
You can even make a surface up to 50% smoother by electropolishing it. Electropolishing can also help finish grooves and joints that are otherwise hard to reach. The process involves removing electric ions from a metal after submerging it in an electrolyte bath.
Doing so can remove debris from the metal’s surface and make it smoother. Electropolishing is also helpful when finishing metals that will be exposed to lots of moisture. That’s because this finish can help protect metals from corrosion.
3. Conversion Coating
Conversion coating, also known as plating, is among the more complex finishing techniques. That’s because it entails changing a surface by introducing other materials to it. This includes zinc, cadmium, chromium, and nickel, among others.
Conversion coating is useful when finishing a metal without enough surface friction or corrosion resistance. That said, conversion coating isn’t as good at fixing surface imperfections as other methods, like electropolishing. However, it can help reduce a part’s electrical resistance and ensure paint and powder easily adhere to it.
Conversion coating also has a nice visual appeal as you can dye the finish to meet your vision. This finish is popular in aerospace applications as it’s lightweight. The durable nature of conversion coating also makes it popular in medical equipment and devices.
4. Polishing
Many metal parts and products call for smooth, glossy finishes. Polishing is the best finishing technique to achieve such a look. After all, some metals come out quite rough after being machined, depending on the process.
Polishing involves using one or several abrasive powders to create a smooth surface. Abrasive powders like chromium oxide, tin oxide, rottenstone, and pumice are especially effective. These powders paired with a leather or felt wheel are perfect for polishing metals.
The main benefit of polishing is that you reduce surface roughness. This is often necessary for items being used in the automotive and medical industries. Polishing makes it easier to paint some surfaces, so it’s a popular finishing technique.
5. Phosphate Coating
Like many finishes, the goal of a phosphate coating is to protect metals like steel and cast iron from corrosion. Fabricators accomplish this via a chemical treatment to boost adhesion and
Keep in mind that phosphate coatings turn out gray or black. This provides fewer options when it comes to the color of your finish. However, it’s worth it for its durability, friction reduction, and corrosion resistance.
6. Anodizing
The electrochemical process that anodizing entails sends a current through a metal that’s soaked in an electrolyte bath. This creates an anodic oxide on the substrate that allows for excellent corrosion resistance. It’s also considered environmentally friendly because it doesn’t produce much waste or emissions.
Anodizing finishes are popular for outdoor applications as you don’t have to worry much about the elements. It’s especially common in construction as metals are exposed to the elements for months before a project is completed. However, this process is also frequently used on metals that are used indoors, such as medical devices.
7. Buff Polishing
Buff polishing is one of the simplest finishing techniques, but that doesn’t mean it’s ineffective. It involves using an abrasive compound with a cloth buffing wheel. The abrasive compound affects the surface while the buffing wheel smooths it out.
Between the compound and the cloth wheel or pad, buff polishing can easily remove imperfections from metal. You can even buff polish other materials, like glass, wood, and even some stones. However, it’s especially effective for finishing steel surfaces after CNC machining.
8. Sanding
Sanding may not be as elaborate as other finishing techniques, like conversion coating, but it’s quite effective. It’s as simple as rubbing an abrasive surface against a metal to alter its texture. Sanding is a popular finishing method used for steel, aluminum, titanium, copper, and more.
The abrasive material you use depends on the type of metal you’re sanding. For example, durable materials like steel are often harder to sand than brass and copper. Sanding steel requires extra pressure and a particularly coarse sanding surface.
What is the Best Finish for Metal?
Many consumers and manufacturers alike consider powder coating to be the best finish for metal. This is largely because of how much durability and corrosion-resistance powder coating offers. It also helps that powder coating is a smooth, consistent, and affordable finishing technique.
That said, some cases call for other techniques. For example, powder coating isn’t always ideal for complex pieces with lots of unique shapes and details. Other methods like electropolishing are typically better for that.
Electroplating is another one of the most popular finishing alternatives to powder coating. That’s especially true for brands that try to achieve a smooth, shiny aesthetic.
Outstanding Metal Finishing Services
As full-service fabricators, we handle everything from drafting and CNC milling or machining to finishing. Finishing is a crucial part of the process as we want your parts and products to be as durable and presentable as possible. Between our impressive 5-stage washer/degreaser, many finishing techniques, and patented racking system, our finishing services stand out.
Call DureX at (908) 688-0800 to ask about our sheet metal fabrication and finishing services.