Sheet Metal Powder Coating

If you're looking to protect and visually enhance sheet metal parts' surfaces, you might consider sheet metal powder coating.

Below are a handful of products that typically receive powder coating: 

• Vehicles
• Doors
• Windows 
• Railings 

While the list above is just a sampling of the types of items that receive powder coating, you might notice the trend that powder coating is applied to products with more size and bulk. 

Powder coating protects a wear-resistant surface that also resists scratches and corrosion. Modern technology provides manufacturers with the ability to provide powder coating on metallic and non-metallic surfaces. 

Before we jump into how the powder coating process works, we will cover the history of powder coating to gain a more thorough understanding of the practice. 

What Is the History of Powder Coating?

The origin of powder coating traces back to Germany in the 1950s. Scientists recognized a need for a more efficient way to apply organic polymers than spray coating. A scientist named Dr. Erwin Gemmer responded to the organic polymer dilemma by creating a new way to apply thermostatic resins by using a fluid-bed application.

Dr. Erwin Gemmer received the patent for his fluid-bed process in 1955. 

Gemmer's fluid-bed process took hold among the public between 1958-1965 and was utilized for its ability to provide electrical insulation, fight corrosion, and protect against abrasion. The fluid-bed application was innovative because previous powder coating application methods involved flame spraying.

It didn't take long for powder coating to evolve as the 1960s brought forth electrostatic applications. 

Electrostatic Application

One of the main issues with the original powder coating method was its inability to control the layer's thickness being produced. 

Cue the entrance of electrostatic application. 

The perks of electrostatic application include a more straightforward application through a spray gun and the ability to control the thickness of the layer being created. 

Dr. Erwin Gemmer's original powder coating process was mostly practiced in Europe and the United States. Once Electrostatic application was invented—it spread worldwide. 

The Overlooked Powder Coating Process 

The 1970s experienced a new powder coating application method that never took hold. Powder slurry application was the name of this powder coating method born and died in the 1970s. 

Processed powder coatings during powder slurry applications were broken up in a sand mill and surfactants and water. The mixture was then sprayed using standard application equipment for a near-identical result as other methods. While this slurry process sounds excellent in theory, a common complaint from manufacturers was that the material clotted during the application process. 

The Current Status of Powder Coatings 

Powder coating is a staple of modern manufacturing and continues to experience evolution through practice refinement. The goal of evolving powder coating techniques is to create a more broad range of applications in automotive, general, and appliance markets. 

With the automotive industry, a vehicle's body, trim, wheels, and hood are all areas that benefit from the powder coating application. It's equally as easy to see how the appliance industry benefits from the resistance and aesthetic perks that powder coating offers. 

Curing is a significant component of the powder coating process that's being improved today. Modern technology must have the capability to cure powder coatings that emphasize appearance at high speeds. Today's rapid level curing is achieved through matching infrared wavelength toward coating and substrate. 

An influx of powder coating manufacturing equipment suppliers and more raw materials supports industrial ability to provide stock product options and small custom batches for powder coating. 

Today, we can use powder coating on sensitive materials like plastic, thanks to refined techniques. Digitalization is going to play a crucial part in the continual growth of powder coating. 

Now that we've provided a brief history of powder coating, let's look at what's going on behind the curtain during the actual process. 

How Does Powder Coating Work? 

The first step of powder coating is pretreating the surface. Pretreatment is composed of multiple steps. 

Once the pieces being worked on are fastened to holders or racks. It's important to note that the pieces being worked on go through the entire coating process when linked to the racks. Manufacturers use racks to help make sure that the workpieces are grounded and experience electrical conductivity. 

During pretreatment, dust, scale, grease, and other undesirable residue is removed. Blasting, grinding, and brushing do a great job of cleaning of parts in pretreatment. After pretreatment, pieces are dried through adhesive water dryers before the paint application begins. 

Powder coating paint application consists of multiple steps, with the first being in-feed and the paint's preparation. Batches of paint are immediately placed into containers while recycled powder is mixed with new powder coating. Paint particles are swirled and shaken to enhance flow properties. 

Transporting paint particles exists through mass and precision conveying. Mass conveying involves transporting more than 5 kg of paint powder per minute. Accuracy conveying consists of powder coating, reaching the spray gun through 50-100g every minute. 

Digital dense phase conveying can be used for mass and precision conveying and benefits manufacturers by not requiring fluidization of the paint powder.

Next up is the charging and application of the paint. 

Paint Charging and Application 

Powder spray pistols are the tools used to carry out powder coating. Most companies use digitally controlled and fully automatic powder coating. Spray booths are often utilized to create a safe application zone. By electrically charging the paint particles, the paint can be applied. 

Ionization is an application method that involves paint particles being guided along an electrode that features voltage levels of 30-100 kV. The point in providing high levels of voltage is to ionize the particle's ambient air. If you're wondering what ambient air is, it's the air in its natural state. 

After the paint particles pass the electric field, air ions gather on the surface. Another electrode at the tip of the powder spray pistol absorbs the ions and dissipates the charge. Ionization is praised for its universal application capabilities. 

The last primary charging application technique for powder coating is Triboelectric charging. 

Electrostatic charges in Triboelectric charging are created by contacting the paint particles with the spray pistol's walls. The frictional process of Triboelectric charging involves electrons being released from the pistol wall coating materials. 

Electrostatic charge can be maintained during atomization in Triboelectric charging. 

Why?

Particles are separated quickly from the spray pistol. 

Triboelectric charging is often used for powder coating jobs that require multiple layers of paint. 

These are the primary powder coating paint charging and application methods, but feel free to learn about other alternative methods. 

Dane Manufacturing Powder Coating

Powder coating is an essential practice at Dane Manufacturing, as most metals can be powder coated. 

Dane Manufacturing provides superior powder coating services thanks to:

• Economic and environmental sustainability
• Class A Paint Line
• Comfort and Efficiency 

We focus on economic and environmental sustainability during powder coating to benefit both our customers and our community. 

Class A Paint line ensures protection against typical dirt in and around a coating operation to provide you with an exceptional final product. 

Our top of the line ovens serves to minimize natural gas consumption and direct heat away from staff for a more safe working environment. 

Dane Manufacturing is proud to provide our customers with powder coating finishes that resist scratches, corrosion, abrasion, chemicals, and detergents.