How to Choose the Right Fastener Coating Type for Your Application？

Engineers and manufacturers often put a lot of thought into which type of fastener they need to implement their designs. However, one important aspect may be overlooked: the coating.

Depending on your application, the type of coating used on a fastener can make or break its viability. But with so many coating options to choose from, it can be difficult to decide which one is best.

We are here to help you. Let's take a look at some considerations to keep in mind when choosing the correct type of fastener coating for your application.

What is Fastener Coating?

Fastener coatings are chemicals applied to metal fasteners to improve their performance and longevity. More specifically, each coating offers varying levels of the following properties:

• Corrosion Resistance - the ability to prevent environmental degradation from chemical or electrochemical reactions. Read our previous post to learn more about fastener coatings and corrosion resistance.
• Lubricity - The thickness of the coating that helps reduce friction and wear.
• Aesthetics - For applications where design and appearance are important (such as furniture), different coatings may have different aesthetic appeal. Alternatively, in military applications, color is often an important consideration for camouflage.
• Health – Chemicals and elements used in fastener coatings can have varying effects on human health. In recent years, there have been growing calls for manufacturers to use less toxic paints.
  

Types of Fastener Coatings

There are dozens of different fastener coating types to choose from. In many cases these coatings are proprietary and belong to a certain manufacturer, but some are more common than others. 

Why is it important to choose the correct type of fastener coating?

As mentioned earlier, the biggest reason for choosing the correct type of fastener coating is that it can make or break the structural integrity of a part. The right coating protects the underlying raw metal from external conditions, extending the life of the part. Structural integrity is a must when your fasteners are working to keep vehicles, machinery and structures functioning properly.

Without the correct coating, your fasteners can be affected by a number of threats including chipping, rust, galling and exposure to other harmful chemicals.

Are there any fasteners that are not suitable for coating?

must! Fastener coatings are not required in some applications, but only if your fastener or the product it is used in is not expected to be exposed to any of the threats listed above.

If you do have an application that does not require a fastener coating, it is in your best interest to avoid it. You can save your factory a lot of time and money during the production process.

How to Choose the Right Fastener Coating Type for Your Application

Now, what you've been waiting for: How to choose the right type of fastener coating for your application. We'll take a look at one of the most reliable methods for selecting and testing fastener coatings, as well as some other important considerations to keep in mind.

National Safety Standards Test

Neutral Salt Spray (NSS) testing is a method of measuring corrosion resistance. The process involves spraying fasteners (with a specific coating) with salt spray for a specified number of hours in a test chamber. Thereafter, inspect the fasteners for corrosion. If they are free of corrosion, they pass the test.

Different types of fastener coatings withstand NSS testing for different periods of time, which helps to rank them in order of corrosion resistance from highest to lowest. This is an important test and consideration when determining the durability of fasteners and coatings, given your application and the elements that will correspond to it.

Additional Considerations for Selecting the Correct Type of Fastener Coating

In addition to NSS corrosion resistance testing, you will need to consider the following when selecting a fastener coating:

• Fastener Material – Most fasteners are made of metal, but selecting the correct coating for a particular type of metal is important. It is also important to consider the material of the fastener connection, as there are many fastener material, coating, and receiver material combinations that can cause galling or seizure.
• Availability - Finding a manufacturer that can apply a specific or rare type of fastener coating can be difficult. Or, if you can find one, they may need some extra time to find it.
• Environmental Impact - Some past common coatings are no longer suitable for new designs due to known environmental toxicity (e.g. cadmium, hexavalent chromium). Or, if you do decide to use paint that isn't environmentally friendly, you might have a hard time sourcing and paying for it today.
• Appearance - As mentioned above, if your application requires a certain aesthetic appeal, it is important that your fastener coating matches it. Many fasteners can be seen in the products and structures they hold together, so choose a coating that matches the color.
• Thickness – Some coatings can be applied in thin layers, while others tend to build up, making threads impossible to measure, and/or increasing the overall diameter of the part.
• Cost - Different fastener coatings have different price tags. Generally, the more corrosion resistant, the more expensive it is - but not always. Shop around to make sure you find one that fits your facility's budget.
  
  Selecting fasteners and coatings can be difficult. Let XIAOJUN help you find your solution! Our customer specified bolts, screws and studs are custom made to meet your application needs and can be purchased in the limited quantities you desire. Please call our team or contact us online for more information.