Anodizing vs Powder Coating: What is best for your Metal?

Once you’ve worked through the stages of selecting a material, designing and manufacturing your part, it only makes sense to select the type of finishing that best fits your project’s application. From wet painting to metal plating there are many different options. In this article, we’ll be discussing the pros and cons of Anodizing vs Powder Coating.

How Does Anodizing Work?

Anodizing is an electrochemical process that chemically alters the outer oxide layer of aluminum parts. It is conducted using a bath of electrolyte solution and an electric circuit, in a similar way to electroplating.

A sacrificial anode is placed in the bath, along with the parts to be anodized, a current is applied and aluminum ions flow from the anode (the part) to the cathode, this makes the surface of the part porous.

This same process then attracts oxygen ions to the surface of the anode (the part), causing a thick and durable anodized layer to be formed. Various chemical solutions can be added to the solution in an intermediary step to add color and texture to the finish.

What Metals Can Be Anodized?

By far the most commonly anodized material is aluminum. But other non-ferrous materials can be anodized, such as Titanium and Magnesium.

Pros and Cons of Anodizing:

• Durability- Because the anodizing finish is absorbed into the top layer of aluminum oxide, it cannot flake or wear off.
• Quality – Because the coating is applied using an electrolyte bath, the finish is perfectly consistent across the whole part, with no risk of paint runs or missed areas.
• Cost – Set-up costs can be higher for smaller batches when compared to wet painting.
• Range of materials – if the anodized finish is a requirement, the range of materials available is substantially diminished to aluminum, magnesium or titanium. All of these are more expensive than steel.

How Does Powder Coating Work?

Powder coating is a relatively inexpensive way of coating parts in a reasonably durable finish. Generally, a thermoset plastic is applied in powdered form to the part. To aid in even coverage, the parts and powder are electrostatically charged.

This results in an even coating of consistent thickness. It also helps the powder stick to some areas that are not directly in the spray of the powder gun, something that wet spray painting can never achieve.

Once the powder is applied, the parts are baked in large ovens, many coating companies use automated track systems to pass the parts through curing ovens, the time required in the oven is dependent on the mass of the parts.

What Metals Can Be Powder Coated?

All the common metals used in industry can be powder coated, including steel, stainless steel and aluminum. The only real limitation is that the material can withstand the 400-degree F curing process.

Pros and cons of Powder Coating:

• Cheap – due to the automated nature of the process, parts can be coated with a uniform finish, good enough for industrial use with much less prep time needed than conventional painting.
• Uniformed – Thanks to the electrostatic nature of the powder application, and the powder’s tendency to self-level when curing, the completed finish is uniform and free of streaks, patches or runs.
• Not as effective for heavy parts – Because the entire part needs to reach the curing temperature of the plastic, without the outside getting too hot, heavy or thick components need a longer cure time. With surging energy prices this can add economy to the process of wet spraying.
• Cracking – Thermoset powder coating can sometimes leave a brittle coating on the parts, if these are subject to scratches or impacts, the paint can chip off in small areas.

When to use Powder Coating or Anodizing?

In general, anodizing is preferred for high-performance or precision parts. For one it leaves a more durable and better looking finish, but it also allows part tolerances to be kept much closer to the original specification. Powder coating cannot achieve the same thickness accuracy as anodizing.

Powder coating, though, is much better at covering larger or unwieldy parts, such as sheet metal components, frameworks and large brackets. It is also able to be used on materials other than aluminum, such as steel and stainless steel.

Typical projects using anodizing:

Anodizing is often seen wherever precision aluminum parts are commonplace, such as in motorsport or aerospace. Common uses include:

• Motorcycle brake levers and bracketry
• Aerospace components
• Lighting and furniture
• Architectural claddings or fascias

Typical projects using powder coating:

Powder Coating is generally a more industrial process, commonly used simply as the cheapest way to protect a part from corrosion, which enables steel to be used where stainless steel is too expensive or unnecessary.

Common powder-coated parts include:

• Industrial bracketry
• Framework for machinery
• Sheet metal covers and enclosures
• Agricultural machinery

Conclusion

Anodizing and Powder Coating are both invaluable to the modern engineering industry, between them, parts from the most simple tools and equipment up to NASA-grade space components can be protected from corrosion and visually improved.

For more information about powder coating or anodizing don’t hesitate to read our more in-depth blogs, if you’re ready to start your project, and need materials, find your local Metal Supermarkets store today.