Monthly Archives: January 2017

What Coaters Need To Know About Powder Coating Particle Size

Powder Coating Particle Size

When troubleshooting your powder coating, you may find specific issues caused by the powder coating particle size.  Unfortunately, while a lot of information is available on this subject, most of it is very technical in nature and doesn’t explain the real-world production issues that are caused by improper powder coating particle dispersion. If you’re looking for practical knowledge to improve your results, these basic guidelines will help you identify finish problems related to particle size.

How Powder Manufacturing Creates Different Particle Sizes

When powder is manufactured, it is combined in a giant mixer, melted, cooled into a big sheet, and then broken up into pieces. It is then ground and sifted through a screen to the specific particle size the powder manufacturer has designated.

During the manufacturing process, there are three types of particles produced: standard, fine and large.

Standard Particle: This particle size is what the manufacturer wants to put in the box. The size range of the particle is very tightly controlled, Standard particles will produce the best possible finish and generate proven, heavily tested results.

Fine Particle: This particle is very small and could cause some finishing issues like picture-framing if there was too much allowed to be packaged. The fine powder particles build up at a different rate from the standard particles, especially in areas of “wrap”, and cause unacceptable variations in the finish.

An excessive amount of fine particles can also contribute to application guns spitting or sputtering because fine particles can be fluidized more easily than standard particles. During the grinding process, powder manufacturers have suction hoses above the grinders to catch a lot of these fine particles that would not otherwise be sifted out. Fine particles, by nature, float in the air more than standard particles. That’s why the suction hoses can catch most them.

For more information, visit this powder troubleshooting guide from Tiger Drylac. Specifically, on page 16 of the document, they show a good example of “picture framing” due to excessive build-up of fine powder. http://www.tiger-coatings.com/fileadmin/user_upload/downloads_us_new/technical-information-sheet/tiger-drylac/TIGER_Drylac_Troubleshooting_Guide.pdf

Large Particles: This particle is too big to pass through the final filter screen. Sometimes manufacturers will re-grind these large particles to get good powder out of them, but sometimes they just throw them away. If large particles wind up in a box of powder because of a manufacturing error or flaws in the screening equipment, they do not hold a charge as well as a standard particle and will most likely wind up on the floor of a spray booth. In addition to decreasing your transfer efficiency, an excessive number of large particles can cause the part surface to be more susceptible to powder loss during pre-cure handling, resulting in thin spots that can’t otherwise be explained. (to learn about Transfer Efficiency, read more here.)

Some fine particles and some large particles will wind up in the powder box regardless of the process being used. The powder coating manufacturer has a particle size distribution analysis machine to measure samples of powder and see how much variation the powder particles have. In a normal box of powder, there shouldn’t be enough large or fine particles to cause problems. 

Typical distribution of powder coating particle size in different powders.

What Is The Powder Coating Particle Size Supposed To Be?

There is no standard answer, because each different type of powder has specific particle size requirements due to the special effects components or pigment used in its formulation. Regardless of size, the key to good powder is generally to have as tight a particle size spread as possible.

Typically, smaller particles carry better charge and fill voids in the coated surface better, but they do not penetrate Faraday Cage areas well. To get a powder that both holds a charge well and creates an even distribution, the manufacturer will usually decide on a happy medium for the average particle size based on laboratory and sample production testing.

Here is an example of a graph of a sample of powder:

Powder Coating Particle Graph

As you can see, there is a curve to the distribution. That means that some particles are a little bigger and some are a little smaller. The more peaked the curve is, the more reliable your finish should be. If the curve is flattened and you have a lot of fine particles or large particles, you could have more finishing problems and/or worse transfer efficiency.

Powder Coating Issues Related To Powder Particle Size

Powder coating particle size discrepancies can create issues with the quality of your finish and can increase your applied cost. These problems can be especially troublesome in a production environment, especially if you use a reclaim system as opposed to spray-to-waste. If you don’t reclaim and reuse spent powder, the particle size in the box is all you have to worry about. If you reclaim your powder, then you need to consider powder particle size even more closely. It’s likely you will have some adjustments to make to achieve your best finish.

“Virgin” powder, straight out of the box, will typically be more conductive than reclaimed powder. The reason for this is that there are some large particles, as well as some inert particles that were part of the original powder formulation. These particles are most likely to fall off the part and get recycled back into the powder supply. As you use more reclaimed powder, this percentage grows and your powder does not adhere as well to the parts. Most powder experts recommend a ratio of at least 60% virgin powder to 40% or less reclaimed powder to get acceptable finish results.

Remember, the fine particles will usually adhere to the part or get stuck in the exhaust filters of the booth, so it’s mostly the heavy particles (that are the least attractive to the parts) that get recycled. Some particles, even those of ideal size, will stick together due to contamination or partial gelling in hot environments. These clumps of small and standard particles act like large particles and don’t stick to the parts during spraying. It is important to hand filter all of your reclaimed powder or use an automatic sieve to filter reclaimed powder being pumped back into your powder hopper.

What If I Think I Have A Powder Problem?

Powder Coating And Color Chart

If you think you may be having a finish issue that’s linked to a problem with your powder, always start by contacting your powder supplier. Powder coating vendors have access to tools that the average powder coating shop or finish line manager does not. Listen to your powder supplier and follow their suggestions. Don’t be shy about asking them to look into potential powder problems, but remember that most coating defects are due to process issues, not defective powder coating media.

In a spray-to-waste environment, your supplier may elect to replace questionable powder or have it analyzed to confirm that it isn’t defective. It’s likely that they will want to review the way your using their product, and they may find a production issue that you’ve overlooked.

If you do a lot of reclaim, your powder supplier can test your virgin and reclaim samples to let you know what you can expect from your powder as far as average powder particle size. By keeping good ratios of virgin and reclaim, you can adjust your guns to the appropriate settings to get repeatable, high-quality finishes.

Need Expert Help?

Reliant Finishing Systems is a U.S. manufacturer of high-performance powder coating equipment. In addition to building powder spray booths and powder curing ovens, we manufacture blast rooms and wash stations. We also have experienced powder coating specialists on-staff and offer line audits and on-site troubleshooting. If you need powder coating equipment or expert advice, give us a call today.

Why Powder Coating Is Good For The Environment

Powder Coated Metal One of the key advantages powder coating has over other finishing processes is how safe it is for the environment and for the people who work with it. Unlike traditional solvent-based wet paint, powder coating is considered a “green” technology that doesn’t generate harmful solvents or airborne pollutants. Compared to painting, powder coating reduces finishing line emissions, produces far less harmful waste by-product, and doesn’t pose a significant health risk to your employees or neighbors. Understanding the impact of these green benefits can help your business make the right choice when choosing a new finishing system—and help you gain support from your community.

Powder Coating Generates Negligible VOCs and No Real Air Pollution

A significant difference between industrial wet painting and powder coating is the presence of Volatile Organic Compounds, called VOCs for short. VOCs (like formaldehyde) are released into the air over time, either as the paint is cured or as it ages. VOCs damage the ozone and, if trapped indoors, can cause serious health problems to people exposed to them. Traditional liquid paint emits VOCs. Newer paint technology includes No-VOC and Low-VOC products, but these are often not capable of providing a finish that is adequately robust. By comparison, powder coated finishes are tough and durable, yet cause the emission of almost no VOCs. Powder coating media and powder coating in general is considered non-toxic, which it is why powder coating is strongly recommended if your finished product will be used or installed indoors.

Since powder coating is inert and produces almost no VOCs, applying it does not create harmful fumes or contribute to air pollution. While you will still want to spray inside a booth with a true filtered exhaust including HEPA filtration, you won’t otherwise have to duct the air from your booth to the outside atmosphere. Although powder overspray is considered a nuisance dust, properly filtered exhaust from a powder coating booth is clean enough to breathe, so you don’t have to exhaust the booth outside the shop space. This makes powder coating even more energy efficient because you won’t be wasting heated or cooled shop air by exhausting it to the outside atmosphere.

Powder Coating Produces Significantly Less Hazardous Waste Than Wet Paint

Traditional wet paint lines produce hazardous waste in two key areas: Retouching and Disposal. Because of the chemical composition of wet paint, coating defects often require costly reworks using solvents. These chemicals produce harmful fumes and the used solvents are considered hazardous waste. In addition, stripped and discarded paint may also be hazardous waste and should be disposed of properly – which can be an expensive and time-consuming process that many shops ignore.

Since powder is considered inert and does not require special handling or disposal, powder coating media is much safer to handle and isn’t hazardous to retouch. Fixing a mistake is also much easier (provided you catch it before curing). Instead of using harsh chemicals, if you find a mistake on a powder coated part, you can simply wipe the part clean or used compressed air to remove the uncured powder and reapply it. Any waste powder can be swept up and handled without special safety equipment, and it can be discarded with normal shop trash.

Powder Can Be Recycled

Powder coating is a two-stage process. First, your product is sprayed with powder using an electrostatically charged powder gun. The powder adheres to the part, but must then be cured inside a powder coating oven to melt the powder so that is flows together and locks onto the part. This process creates a strong and very durable bond that lasts and helps protect the metal underneath. (You can even increase this durability with different pretreatment methods – for more information on pretreatment, take a look at our Pretreatment Primer.) But what about the powder you spray that doesn’t adhere to the part?

The excess sprayed powder can be recycled using a process called powder reclamation. This works best when only one or two primary colors are used for your products, as multiple color changes can drive up equipment costs considerably (for more information, see our powder coating gun article here). However, if you are only using spray one or two colors most of the time, then you can see significant savings by reclaiming the powder overspray that gets trapped in the filters or falls to the floor of your spray booth. (For more information on how much powder you can reclaim to increase powder transfer efficiency, click here.)

Powder Coating Already Complies With Environmental Regulations

Because powder coating is considered non-toxic, is inert and produces negligible VOCs, it already meets or exceeds many national environmental protection standards. Although your shop will need to clarify with your local authorities, powder coating is considered safer and will not require the same level of oversight and waste disposal care that wet paint operations do. Also, because powder coating media doesn’t present a spill hazard, you don’t to invest in a paint mix room or storage room.  As long as the powder coating equipment you purchase meets national safety codes, your operation will already meet or exceed national environmental regulations.

All Reliant Finishing Systems’ Equipment Is Produced To Meet Or Exceed National Codes

If you’re looking for safe and effective powder coating equipment, look no further than Reliant Finishing Systems. Our powder spray booths and powder curing ovens are designed specifically for powder coating applications and can be customized to fit your shop’s exact application. Whether you’re a finish line manager seeking a turn-key automated powder coating line, an established powder coater in the market for new equipment, or a fab shop owner wanting to get started with powder coating, Reliant can help.

Have questions? Email us or give one of our systems specialists a call today or visit our Resources page.

 

Dealing With Unhappy Powder Coating Customers

powder-caoted-part-with-coating-contamination

If your powder coating has chips, bubbles or has contamination (shown above) your customers won’t be pleased.

As a job shop owner, powder coating specialist or coating line manager, you’ve probably dealt with unhappy powder coating customers. Dissatisfied clients can have a number of complaints: some customers are sensitive to price, others may be sensitive to turn-around times or coating mil thicknesses, others may be unhappy with overall finish quality or other issues. Unfortunately, you may not know why a customer is unhappy until the very end of the project or after the order has shipped. Whether they complain face-to-face, you hear about their remarks from someone else, or you see a negative review online, a dissatisfied customer can be frustrating to you and disruptive for your business. What’s worse, if you ignore them, it’s likely that a problem customer will only get worse. Business experts agree that when it comes to dealing with mad customers, there’s only one “right” way to react: Contact them, take some kind of action to address their grievance, and most importantly, act quickly.

What angers already-irritated customers most? Being ignored or left waiting too long for a resolution to their problems. By responding to a customer’s complaints, you validate their need to be heard. Let them know your business is willing to listen. Approach your customers with genuine concern. View customer complaints as opportunities to demonstrate your shop’s commitment to customer service. A positive, friendly outlook will likely win over frustrated customers – as long as they have realistic expectations.

Reliant Finishing Systems builds and sells powder coating appliances. They deal with customers from around the world through various websites and conventional resellers. Their staff monitors digital media constantly to provide quick responses to customers who publicly voice their dissatisfaction. They also actively contact buyers within days of providing equipment so they can learn about potential problems before they get out of hand.

When dealing with their customers, powder coating shops can assure customer satisfaction by using a similar approach. Don’t use the “No News Is Good News” approach. Have an employee or third-party company proactively reach out to all of your customers to find out what they really think about their experience with your company. By documenting all of the comments–not just the good ones–you can get a better picture of what you’re doing right and where you need to improve. Some problems are truly isolated cases of miscommunication or poor performance, while others may be part of a larger issue.

One area that powder coating shops can immediately increase customer satisfaction is through improved quality control. Many of the complaints you are likely to receive will be due to a perceived lack of finish quality, whether that is poor coverage, uneven application, bubbling, or other coating issues. By adding a rigid and consistent quality control regimen to your process, you can catch many mistakes long before they reach a customer, saving you time and increasing customer satisfaction. (For more information about adding quality control to your process, check out our Introduction to Powder Coating Quality Control Testing.)

Grow Your Business With Increased Customer Satisfaction

Michael Schuerer, President of Reliant Finishing Systems, believes that attention to customer service has helped the company’s rapid growth. “It’s important to constantly listen for negative feedback and approach it rationally when you encounter it. We’ve found that it’s easy to get defensive or discount what a particular customer has to say, but that doesn’t help you grow your business or improve your brand. Sometimes you just have to pause and look at the situation with a fresh perspective. Successful companies treat their customers with respect, even when that proves challenging. Reliant wants to make sure our customers are pleased with both the equipment and the support they receive from us, so we try hard to assure that our customer service decisions are fair and thoughtful.”

Reliant recently had a frustrated customer post something negative about the company on Facebook. Within a few hours of his post, the company called to resolve the issue. That level of awareness and responsiveness can help you grow your reputation, but it takes consistent effort. It also takes patience to remember that you’re dealing with real people who can be very emotional once they’re unhappy. It may be difficult to address a customer’s complaints, but it’s worth it in the long run.

Even if your shop’s budget prevents you from hiring a PR firm or performing elaborate customer satisfaction surveys, there are three things you can do to help keep your reputation intact:

BE AWARE. Go to business expos and civic meetings that your customers attend. Listen to what’s being said. Try to interact with customers in a way that makes it easy for you to learn just how happy or unhappy they are. Set up notifications on your Facebook page and any other online outlets you use to interact with customers or sell online. Check your pages and your customers’ blogs or forum comments routinely to make sure they are happy with your company.

BE ACTIVE. Reach out to frustrated customers immediately. If nothing else, let them know you’ve received their complaint and you’re company is working to resolve it. Problems are usually much easier to work out if the customer gets a personal touch. A face-to-face meeting is better than a phone call, and a phone call is better than an email or private message.

REMAIN ENGAGED. Keep in touch with unhappy customers to resolve their issues and, when appropriate, offer compensation for their time and trouble. Sometimes a simple apology is all that is needed. At other times you may need to consider reworking bad parts or offering a discount on future orders. By staying involved with your customers, you help assure that their complaints are resolved—and that you have the opportunity to do work for them in the future.

By staying engaged with problem customers and proactively reaching out to your existing clients, you can not only help solve their issues – you can help identify areas where your company does need to get better. A company that is known for helping to solve problems, reacts positively to critique and works to actively improve their relationships is a company whose reputation will grow and whose business prospects will increase.