How Does Powder coating booth Work?

If the product you want to powder coat has a lot of debris (rust, laser scale, preexisting paint), then you will likely need a Blast Room. A blast room is an enclosure where you use compressed air to propel abrasive material against the surface of your parts. Depending on the situation, you would typically use either an appropriate blast media (grit) or steel shot to blast all the unwanted debris off your part until it has a clean metal surface that’s ready for powder coating. Blast rooms are especially useful for job shops that work with raw materials that aren’t pristine, such as plate steel or tube stock that has areas of oxidation or welding residue. (For more information on getting the right blast room, go here.)

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If oils, solvents or chemical residue covers any part of your products’ surface, you’ll want to consider a Wash Station. A wash station is where you spray your parts with a detergent and/or chemical pretreatment agent, such as iron phosphate. Using hot water or steam to clean and then chemically prep parts is quite common. A wash station helps you increase powder adhesion and improve finish quality, even if the parts have already been blasted. Some wash stations require you to apply the chemistry manually using a spray wand. Other washers are automated and the parts travel through the cleaning, rinsing and prep stages on a conveyor.

In some operations, pretreatment requires the use of a Dry-Off Oven. This is commonly an appliance similar to a curing oven, but where the just-washed parts are heated in order to evaporate any water or chemistry still on them. This step can also help parts reach an optimum temperature for powder application.

Pretreatment equipment is incredibly useful for your operation and can make a big difference in the quality of your work, but an elaborate system isn’t always required for powder coating. While we can’t stress how important it is to have a clean surface before you apply powder, expensive pretreatment equipment isn’t mandatory for entry level coating operations where hands-on cleaning (such as with a tack rag and solvent) can be employed as needed.

Application: Powder Guns and Powder Spray Booths

Powder coating application is almost always done with a special Powder Spray Gun. In order for powder coating to work effectively, the powder must be electrostatically charged. The only way to apply this charge is with a spray gun designed exclusively for powder coating. Compressed air moves powder through the gun from a hopper or directly from the box the powder is stored in. The compressed air blows powder out of the gun as a tightly formed cloud. As the powder leaves the gun, it receives an electrostatic charge. Once charged, the powder cloud envelopes the part and the powder sticks to the surface of the grounded part (which is one of the reasons why powder coating equipment is so easy for new operators to use).

If you want to powder coat, you need a powder coating gun. There are many types of powder spray guns available on the market. We always recommend investing in a professional-grade powder gun, as they are more reliable and provide better results.

Once you have your powder gun, you’ll need to have a place to use it. Whenever you spray powder, some of the powder will end up on the floor and in the air instead of on your products. This leftover powder is referred to as overspray. Keeping this overspray out of your workspace is one of the functions of the Powder Spray Booth.

The powder spray booth is designed to keep the rest of your shop clean while providing a well-lit area for you to apply powder coating. All powder spray booths will have one or more exhaust fans. The exhaust will use filters to capture at least some of the overspray. If the exhaust works properly and the filters are maintained, the airflow in the booth should keep the overspray inside the enclosure and enable the painter to see what he’s doing. If your shop environment includes welding or blasting areas, filtered doors on the spray booth can keep airborne contaminants out of your powder coated finish.

Numerous booth configurations are available, and getting the ideal booth depends largely on what you’re coating, your floor space availability, and your workflow requirements. Powder spray booths can be open-faced or have doors on one end. They can also be tunnel style enclosures with the filtration built into the floor or wall(s). If you have space constraints, a Powder Spray Wall may help you get the airflow and filtration you need. A spray wall is just a large filtration system—essentially a spray booth without walls or a roof.

If you want to recycle your powder, you need to make sure your powder spray booth is built with a reclamation system. Usually this system will rely on pleated cartridge filters. These help you recover some of the overspray and reuse it. This can be very cost-effective if you are planning to use only one color and type of powder for your coating. The spent powder is trapped in the filters and then dislodged into a recovery bin for reuse. In more advanced systems, the powder is automatically reconditioned, mixed with virgin powder, and then returned to the supply hopper feeding the powder gun(s). If you are planning to reclaim a variety of colors, a set of removable filter modules is required. Unfortunately, the cost of buying multiple reclaim modules can add up quickly because you can only reclaim one color in each filter module.

No matter what type of booth you decide on, you’ll need a powder spray booth if you want to get quality results and maintain reasonable throughput from your coating operation. (For more information on what size powder spray booth you might need, click here.)

If you have stringent finish requirements, you may also need a Clean Room (also called an Environmental Room). This is usually a climate-controlled room built around the powder application area. The purpose of a clean room is to eliminate airborne contaminants and control the temperature and humidity during powder application to prevent any sort of contamination, clumping or consistency issues when applying the powder. Clean rooms are often recommended if your shop environment is particularly dirty or your products require an exact specification for adhesion or salt spray tolerance. (For more about requirements, click here.)

Curing: Powder Curing Ovens

After your product is powder coated, the final step is to place it inside a specially designed Powder Curing Oven. They usually operate between 325° and 450° Fahrenheit. Once the oven is up to temperature, the temperature stabilizes. The coated products are exposed to precisely heated air for a set period of time. Once the curing process is complete, the parts are removed and allowed to cool before being handled.

Some ovens use infrared emitters to heat the surface of the coated parts, but these types of electric powered or gas catalytic ovens can be costly to buy and expensive to maintain. More commonly, ovens rely on electric heating elements or a natural gas or LP-fueled heat system. These more conventional ovens typically rely on heated air moving over the parts for convection curing.

The time it takes to cure the powder varies greatly depending on the size, shape and thickness of the parts being coated. A small, light-gauge bracket can take as little as ten minutes to cure completely, while a 20’ section of heavy-walled pipe may take over an hour to cure properly.

If you want to powder coat at a professional level, the type of oven you choose is critical.  Not only are brand-name powder curing ovens designed specifically to generate premium coating results, they are also highly efficient appliances in terms of fuel usage and energy costs. It’s likely that you’ll be using your oven several hours per week, so the cost of an inefficient design can quickly sap your profits.

Similar to powder spray booths, powder curing ovens come in multiple sizes and configurations. (For more information on what size powder coating oven you will need, click here.)

Professional Powder Coating Systems Layouts

There are two basic configurations for any powder coating line: batch or automated.

A Batch Powder Coating Line is usually a system where the parts are prepared, coated and cured in batches of multiple parts, with operators handling up to dozens or hundreds of parts at a time. The products are usually hung on metal rolling racks, which move with the parts throughout the coating process. (Remember: high-temperature or metal casters for your racks are very important!) With a batch line, parts are usually moved from stage to stage manually, and the term “batch coating system” is also commonly used to describe operations where large objects are coated individually after being moved by hand or with machine.

An Automated Powder Coating Line uses basically the same appliances as a batch system, but connects many or all of the stages via a motorized conveyor that moves the parts through at a constant rate. The products are usually loaded onto the conveyor at a set location and move through each stage, where either manual operators or automated devices clean and prep the parts and apply powder to them. Once coated, the parts move through the curing oven and then cool as they travel along the conveyor to a point where they can be unloaded.

(For more information on whether a batch coating line or an automated coating line is right for your business, follow this link to learn more about the advantages and disadvantages of each system.)

Powder Coating Equipment From Reliant Finishing Systems

Hopefully this Beginner’s Guide to Powder Coating Equipment has answered your basic questions about what powder coating is, how it is done, and what you need to start your first powder coating line. If you would like to learn more, please give us a call at (888) 770-. Reliant Finishing Systems’ specialists can help! We’ll guide you through the process of setting up a powder coating shop or adding coating capabilities to your existing fab shop or manufacturing facility. Whether it’s your very first powder coating system or you’re upgrading to a complete automated line, you can trust Reliant to provide you with sound advice and affordable, high quality equipment.

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Powder coating provides a durable, lasting alternative to liquid paint. Its application process requires careful pretreatment and an electrostatic charge to adhere the pigmented coating onto the surface. With powder coating, surfaces have protection and visual enhancement, making this finish an ideal option for many industries.

Table of Contents

• Powder Coating Definition
  • What Is Powder Coating Made Of?
  • Types of Powder Coating
  • What Is Powder Coating Used For?
• How Does Powder Coating Work?
  • How Powder Coating Sticks to Surfaces
  • How Powder Coating Protects Surfaces From Corrosion
• What Is the Powder Coating Process?

Powder Coating Definition

Powder coating is a dry powder applied to a charged surface, creating a thicker coating in one application more than a single coat of paint. An electrostatic charge holds the coating onto the surface, which remains in place after curing the object. Due to the intensive process required to prepare and coat the surface, powder coating is a practical approach for large-volume orders.

What Is Powder Coating Made Of? 

Powder coatings consist of several ingredients. A polymer resin creates the finish’s core. Additional elements in the coating include ingredients to help with curing, pigments to add color, and flow modifiers. These parts work together to create a colored, protective surface that performs well in many environments after curing.

Types of Powder Coating

Generally, there are two types of powder coating – thermoplastic and thermoset. These differ in their curing methods and properties.

First, thermoplastic is a coating that melts and flows when heated, yet maintains the same chemical composition once it solidifies. It offers better resistance to impacts in the finished product. Plus, it does not need a curing cycle. Instead, the coating requires time and high temperatures to melt, flow evenly over the surface. Because it does not undergo curing, it can soften and remelt when subjected to high temperatures. Thermoplastic powder application requires a much thicker millage than thermoset powder coatings and often does not offer as nice of a visual appearance as compared to a thermoset. 

Secondly, thermoset powder coatings go through an irreversible chemical change during curing to create a long-lasting, hardened coating. While thermoset coatings still melt and flow when heated, their structure chemically cross-links to form a different chemical composition than the base resin. Because the changes after curing are permanent, this type of coating will not remelt under intense temperatures. Plus, it provides better scratch resistance compared to thermoplastics. Thermoset powder coatings develop thinner films, which can be more visually appealing than some thermoplastic. However, when applied in thick layers, it can become brittle or crack.

Because these types of powder coatings have different properties, the best choice depends on the finished product’s application and use.

What Is Powder Coating Used For?

Powder coating has many applications in automotive, aerospace, manufacturing, and other industries that require durable finishes for products. Thermoplastic coatings can be beneficial in functional settings, such as dishwasher racks, playground furniture, light poles, and pipes. Meanwhile, thermoset powder coatings are useful in a wide array of applications, from lawn and garden products such as mowers or shovels to furniture, fencing, building facades, and many, many more.

How Does Powder Coating Work?

Powder coating uses an electrostatic process and curing to adhere the powder to the surface. Because the parts must undergo high temperatures to set the coating, the substrate must also be heat-resistant. However, most products coated with this finish are metal and easily hold up throughout the process.

How Powder Coating Sticks to Surfaces

Surfaces that use electrostatic applications have the metal components grounded. While the powder itself is inert, it gains an electrostatic charge as the particles pass through the spray guns. The guns have an electrode fitting that adds an electrical charge to the powder particles. When sprayed onto the grounded surface, the particles stick. They become solidified into a dense coating during the curing process that melts and sets the finish.

Another less frequently used method is a curing fluidized bed. This method heats the part first. Next, the heated part submerges into a bed of powder coating. The heat melts the coating, which covers the surface evenly. This method works for thermoplastic coatings and non-metal materials.

How Powder Coating Protects Surfaces From Corrosion  

The durable powder coating provides a thick surface over the part. It resists damage from impacts and scratches. Unlike paint, powder coating generally does not require touch-ups due to chipping or fading. It provides long-lasting color for applications in harsh environments.

What Is the Powder Coating Process?

The powder coating process includes several steps, each of which helps ensure the finish’s success, longevity, and durability.

Blasting

Blasting is a step used to remove inorganic contaminants, like welding smut, rust, and laser scale, or for previously finished surfaces. The blasting process uses abrasives to take off paint or other finishes, rust, or corrosion. By ensuring the surface does not have contamination, the finishing company can ensure better powder coating adhesion.

Pretreatment

The most critical step of the powder coating process is pretreatment. This step is so crucial that we use an eight-step pretreatment method. First, an alkaline cleaner takes off organic liquid and dust contaminants. This stage finishes with two thorough rinses to remove all surface debris and cleaning chemical. 

Next, the part undergoes an iron phosphate application to prepare the surface for better powder coating adhesion, and improved corrosion resistance. Dual rinses get all traces of the iron phosphate from the part’s surface.

A reverse-osmosis water rinse removes any remaining solutions from the surface. Finally, a chrome-free zirconium sealer covers the surface. This layer dries in place and seals the surface, readying it for the following stages of powder coating.

Primer

A primer added to the surface before the powder coating application is optional. However, it can help the finish on aluminum or steel products last up to four times longer than non-primed surfaces. Therefore, consider priming aluminum or steel components intended for outdoor use.

Masking

Masking blocks off areas of the part that do not need powder coating. It protects these areas from the coating process and ensures clean threads or machined areas. 

Coating

The coating process has either an automatic system or a professional finisher, which spray the grounded metal parts with charged powder coating. The coating sticks to the surface through electrostatic bonds.

Curing

Curing melts the resins in the powder and turns it into a durable coating. The timing and temperature used for curing depend on the coating thickness, substrate material, item size, and other factors. Professionals use these aspects of the part to calculate the precise curing time. After curing, the part cools and moves on through packaging and shipping.

Connect With Keystone Koating for Professional Powder Coating Services

Reach out to Keystone Koating for commercial or industrial-grade powder coating services. Our eight-stage pretreatment process ensures quality adhesion of powder coating that lasts. Plus, we can provide quick turnarounds for large-volume orders. With our turnkey solutions, your business benefits from a complete coating process that starts with blasting and ends with packaging and shipping. We’ve been trusted for over 30 years on industrial or commercial projects such as yours. Contact us for a quote

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