Take a quick peek around your office or shop and tell me you found two non-powder-coated items within one minute.
I’ll wait.
Powder coating has gained popularity over other coating methods because of its wallet-friendly price, eco-friendly features, and high-quality finish.
Paraphrasing a line in a movie, with great popularity, comes responsibility.
Not only does the powder coat need to look great, but it also needs to last.
How is that tested? Quality. Quality testing is critical in industrial powder coating applications because it finds any defects or inconsistencies in the coating process.
Quality Testing for Industrial Applications
Suppose a powder-coated component lives in harsh conditions, such as extreme heat, corrosive chemicals, and water exposure. In that case, it must undergo extensive quality testing before leaving the facility, and quality testing help ensure the coating withstands these conditions while maintaining its integrity over time.
Quality testing identifies defects or inconsistencies in the coating process and handles them before completing the project.
Discovering and fixing these issues reduces the risk of failure in the field when repairing or replacing becomes quite spendy.
Common Quality Testing Methods
Companies performing quality testing usually use one of the following methods.
Adhesion Testing
Poor powder adhesion leads to coating failure, reducing the product’s lifespan. Adhesion testing determines the bond between the coating and the substrate. This test starts by applying a strip of tape to the coated surface and then pulling it off. Quality techs measure the amount of coating left on the tape to determine the coating’s adhesion strength.
Impact Testing
In central Wisconsin, we still have several gravel roads, and having a small rock chipping your impact-resistant component isn’t simply frustrating but expensive—replacing it takes time and money.
Impact testing evaluates the impact resistance of the coating and involves dropping a weighted object onto the coated surface from a specific height. The amount of damage to the coating is measured to determine the impact resistance of the coating.
Salt Spray Testing
Walking around Rib Mountain State Park, you’ll find metal benches overlooking the beautiful scenery.
Take a closer look, and you’ll find nary a patch of rust on those benches.
Why?
Because odds are, after fabrication, the benches had an e-coat/top coat process—an e-coat bath followed by a powder coat.
The powder coating provides the first layer of protection against corrosion, while the e-coat brings the big guns, so to speak. Components are bathed in an electrostatically charged solution, covering all surfaces.
If a fabricator paints or powder coats a bench exposed to weather, a simple chip leads to rust, which looks ugly and reduces the bench’s lifespan.
Salt spray testing evaluates the corrosion resistance of the coating by exposing the coated surface to a saltwater mist for a specified period. They measure the amount of corrosion that occurs on the coated surface to determine the corrosion resistance of the coating.
What Factors Affect Quality?
Powder coating quality depends on several factors, the most important being surface preparation. But that’s only one factor; coating thickness and curing times are others:
Surface Preparation
In any process, there’s that first, crucial step. When powder coating, don’t underestimate the importance of surface preparation!
The surface must be clean, dry, and free of contaminants like oil, grease, and rust; not removing them plays a big part in problems down the road.
Coating Thickness
When it comes to coating thickness, the Goldilocks zone rules supreme.
An easy example of the Goldilocks zone is the rock we call Earth. A little closer or further away from the sun, none of us are here. Luckily, our orbit is just right.
Now, apply the Goldilocks zone to the powder coating. If the coating is too thin, it may not provide adequate protection; if it’s too thick, it may crack or chip.
It has to be just right.
Curing Time and Temperature
The Goldilocks zone also applies to curing a powder-coated project.
Too much or too little heat creates problems because poor curing produces a poor powder bond to the substrate, and a poor bond means a limited lifespan for a component.
Using the correct curing time and temperatures during the process becomes a crucial step for powder coating.
Benefits of Implementing Quality Testing
We place two watches on a table before you, and each efficiently tells time and shows the date.
At first glance, it is difficult to differentiate between the two watches based on their primary functions.
However, one is a Timex® watch, while the other is a Rolex®. Although the former is a good watch, we know the other for its legendary quality.
But what exactly is quality? According to Aristotle, quality is a habit.
When a company incorporates a quality program over an extended period, it develops a culture of pure quality that becomes a mindset.
The SeaGull Watch Company of Tianjin, China, makes Timex watches. Although their process may involve sourcing gears and springs at affordable prices, it does not equate to high-quality materials. This approach helps to make Timex watches affordable for most people. You can get an excellent Timex watch for less than $100.
An inexpensive Rolex runs about $5,000, and the watch enjoys the precision expected from Swiss watchmakers.
The quality of a Rolex watch is a crucial aspect reflected in:
- The steel used
- Manufacturing technology
- Rigorous quality control
- And the fact that every Rolex timepiece is crafted by hand in Switzerland.
Why in the world are we talking about watches, you ask?
Simple. Manufacturers who spend the capital on quality people, processes, and tools to run their quality department produce next-level components—every time.
Among the benefits found in excellent quality control include:
Improved Quality
Does the finished component meet specifications? Knowing the answer improves product quality and reduces the risk of defects not seen until it’s in the field.
Reduced Production Costs
Doing it right the first time is a dated cliché. Unless you’re Mozart, it doesn’t happen.
Using a rigid quality department finds and eliminates defects. Eventually, if disciplined, the production improves its process, streamlining it by reducing waste and eliminating mistakes.
The result? Eventually getting there: eliminating wasteful processing that reduces the cost of production.
Improved Customer Satisfaction
Improved Quality + Reduced Production Costs =?
Answer: Happy Customers
If a powder company provides exceptional quality at lower production costs, it should exceed customer expectations, right?
Proper quality testing, as explained above, results in increased customer satisfaction and loyalty.
Easy, right?
Well, not quite; it all sounds great until theory meets reality.
Quality Testing Challenges
As we know, life doesn’t occur in a vacuum, and all plans fall prey to the Butterfly Effect. The butterfly effect says that small things have big effects— a butterfly flapping its wings causes a hurricane far away.
There are several challenges quality testing must overcome. Here are three:
Variability in Testing Methods
As the idiom goes, there’s more than one way of skinning a cat. In this case, there’s more than one way to test powder coat quality. Each test result depends on the method and person performing the test. Consistently using the same testing methods ensure consistent data points, providing reliable results.
Environmental Factors
Wisconsin weather is great: if you don’t like what you see, wait an hour, and it changes! We range from -35 ºF with wind chills double that to 110 ºF with dew points in the 70º range.
Those drastic variations directly affect testing results, making environmentally controlled facilities a critical piece of the quality testing puzzle.
Equipment Calibration
We see the inspection stickers at gas pumps and the scales at meat counters, ensuring the device is calibrated for accuracy.
The same holds for testing equipment. Regular calibration ensures accurate and reliable results.
Technology Advancements
Life moves fast, but technology is faster! For example, look at GPT-3 and how it’s changing the digital world nearly overnight.
Technological advancements haven’t ignored quality testing for powder coating; examples include:
Non-Destructive Testing
I spend a great deal of time in Photoshop editing images. One lesson I learned long ago is the ability to edit without destroying the image I’m working on. Photoshop provides tools to change, not destroy, images.
For testing powder coating, infrared thermography evaluates the coating’s quality without damaging the surface, reducing waste and improving efficiency.
Digital Imaging
Digital imaging visually evaluates the quality of the coating, helping identify defects or inconsistencies that may not be apparent through traditional testing methods.
Automated Testing
Automated powder coating quality testing uses specialized equipment and software to assess the quality of powder coatings.
Some common methods of automated powder coating quality testing include:
- Spectrophotometry: Measures the color and gloss of the coating, ensuring it meets the desired specifications.
- Electrostatic charge measurement: Measures the charge on the powder particles, ensuring the coating is uniform and consistent.
- Cross-cut adhesion testing: Makes a crosshatch pattern on the coated surface and uses tape to determine the coating’s adhesion strength.
- Film thickness measurement: Measures the coating’s thickness, ensuring it meets the required specifications.
- Gravimetric testing: Weighs the coated part before and after baking to determine the amount of powder that adhered to the surface.
In Sum
The future of quality testing in industrial powder coating is bright, with technological advancements likely leading to further improvements in the testing process, making it faster, more accurate, and more efficient.
As the demand for high-quality powder coating continues to grow, quality testing becomes increasingly important, ensuring a powder-coated job meets a customer’s expectations while living a long, happy life sitting atop Rib Mountain!