Archives

Manual Powder Coating Gun Comparison: Box-Fed vs Hopper-Fed

Venturi Pump - Wagner Manual Powder Coating Gun

Typical venturi pump from a Wagner manual powder coating gun system.

If you’ve been shopping for a manual powder coating gun, you’ve already seen the terms “box-fed” and “hopper-fed.” In this article, we’ll explain what those terms mean, how they affect your powder coating process and how picking the right gun configuration can dramatically improve your results.

Every professional quality manual powder coating gun has an integrated delivery system for preparing the powder and bringing a steady stream to the application gun. The powder flows through the hand-held application gun as it is sprayed onto the part being coated. Both box-fed and hopper-fed delivery systems provide powder to a venturi-type powder pump, but these two preparatory feed systems have different attributes. You’ll need to consider which system will work best for you before buying a new powder coating gun.

[Author’s note: We’re showing Wagner products for this article, but other brands look very similar.]

Box-Fed Powder Coating Guns

Wagner Box-Fed Manual Powder Coating Gun

Wagner box-fed powder gun with pick-up tube shown outside of a box of powder.

A box-fed powder coating gun draws powder coating media directly from the box provided by the powder supplier. A platform holds the powder box at an angle on a stand below the gun’s controls. A powder pick-up tube is then inserted into the powder in the box. The pick-up tube hangs vertically and usually has a small amount of compressed air delivered to the tip area to break up any compacted or clumpy powder. This helps assure uniform powder flow. The tube routes the powder up to the venturi powder pump, which sends the powder to the gun itself.

During operation, the platform which holds the box constantly vibrates. This vibration causes the powder to shift around inside the box. The powder in the box moves constantly and replaces the powder that is being pulled up the tube. This prevents “rat holes” from developing in the powder still in the box. Without constant vibration, the powder would be supplied in surges, which would create problems during application and degrade the finish.

Advantages of Box-Fed Powder Coating Guns

1) Fast Start-Up: Grab a box, open it up, put the pick-up tube in and start coating!

2) Quick Color Change: It takes as little as 3-5 minutes to change colors when using a box-fed gun with air pulse cleaning. Less expensive models may require up to about 10 minutes. You simply clean or swap the hoses, switch to a different box of powder and go back to work.

3) Lower Initial Investment: If you spray a variety of colors and textures each week, the cost of buying multiple hoppers can really add up. Since the powder you buy already comes in a box, there is no extra cost associated with dealing with lots of different powders.

4) More Mobile: There’s less weight to move around your shop when working with a box instead of a hopper on the gun cart.

Disadvantages of a Box-Fed Powder Coating Gun

1) Special Effect Powders Won’t Work: Since the vibratory box feed system tends to cause larger or denser particles to settle to the bottom of the box, any powder that has distinct particle size differences can have consistency issues, especially as you get closer to the end of the box.

2) Humidity Can Cause Problems:  To get best results and prevent powder from degrading while in storage, you should keep your powder in a cool, dry, climate-controlled area. If you are starting a new project and you bring powder into a hot and humid shop environment, you can encounter troublesome powder clumping due to condensation occurring when the cool powder is exposed to the humid air.

IMPORTANT:  When working in hot or humid environments, bring out a box of powder a couple of hours before you need it and open the top to allow the powder to acclimatize to the environment before you start spraying with it.

3) Spillage And Contamination: Although it isn’t easy to do, you can tilt the gun cart by accident and spill the powder out of the box. You can also get contaminants in the powder if you try to reuse spilled powder, or if you have a dirty shop environment and leave the opened box of powder in use for a long period of time.

Hopper-Fed Powder Coating Guns

Powder Coating Gun - Wagner Hopper Fed Gun

Wagner hopper-fed powder gun with powder pump attached to a 60-liter stainless steel hopper.

A hopper-fed powder coating gun holds the powder in a sealed (usually stainless steel) container that has a perforated plastic membrane on the bottom. This membrane has tiny holes in it that allow compressed air to enter the container and constantly fluff the powder so that it flows around inside the hopper. This process is called fluidization. When you look at the top surface of the powder in a hopper that is being fluidized by compressed air, it should look like it is boiling. If you put your hand in the powder while it is being fluidized, it should feel silky smooth.

The compressed air supply to the hopper should be adjusted so that powder isn’t wasted due to excessive agitation/over-pressurization of the container. While some powders require a small amount of venting, you should adjust your system for minimal powder loss, especially if you are reclaiming the powder as an on-going process.

Specific Advantages of Hopper-Fed Powder Application Guns

1) Conditions The Powder: The fluidization process helps remove moisture in humid environments by introducing clean, dry air from the bottom of the hopper.

IMPORTANT: Never stir the hopper with a stick! It can damage the plastic membrane on the bottom of the hopper, reducing the effectiveness of the fluidization airflow.

2) Mixes The Powder: Fluidization also insures that the powder is thoroughly mixed. This is important if you are regularly spraying river textures or bonded metallic powders, or making a transition from one batch of the same powder to the next.

3) Less Chance of Powder Contamination: The hopper is sealed off from the surrounding environment and each hopper is typically used for only one type of powder.

4) Less Surging: Because the powder is better conditioned, the pump picks up the powder more consistently and the gun delivers it more uniformly.

Disadvantages of Hopper-Fed Coating Guns

1) Increased Cleaning Time: If you have only one or two hoppers for all of your colors and textures, it can take a significant amount of time to switch between colors or textures—up to one hour per change if done meticulously.

2) Cost/Storage Issues: If you buy multiple hoppers to accommodate all of your most commonly sprayed powders, it can be costly. It can also be challenging to store hoppers when they are not in use. You may end up using valuable floor space to store empty hoppers, particularly if you don’t normally carry some common powders in inventory and get them on demand from your powder vendor.

3) Reduced Throughput: If you commonly have to move the cart around a good bit because of the size or complexity of what you are coating, having a hopper-fed gun can slow you down. A gun cart loaded with a full 60-liter hopper (the most popular size) can be a bit unwieldy.

Which Powder Coating Gun Is Right For You?

Depending on your work environment, getting the right configuration can make a significant impact on your performance. If speed (how fast you can get started on a new project), agility (how fast you can change colors or textures) and lower cost are key concerns, a box-fed gun may be the right choice for you. If premium finish quality is the most important goal, a hopper-fed gun is probably the right tool for the job.

Box-fed powder coating guns are best suited for:

1) Job Shops: If you spray different powders for different jobs, guns that are box-fed let you change colors quickly between projects.

2) Regular Powder: If you don’t do a lot of special effects, box-fed guns work fine with most single color powders.

3) Small Powder Runs: If you only powder coat a small number of parts the same color during the week, a box-fed unit is perfect for projects where you’ll only be running a few pounds of a specific powder at a time.

Hopper-fed powder guns are recommended for:

1) Limited Color Applications: If you only use a handful of different powders, a hopper-fed gun is usually a better value.

2) Special Effects: As noted before, if a special effect powders are an important component of your process, having a hopper dedicated to each of these powders would be best. Special effect powder must remain fluidized to be applied properly, and a box-fed system simply won’t cut it if you need professional quality results.

3) Reclaim: If you reclaim your powder, you’ll need a hopper-fed gun. The hopper-fed system enables you to mix reclaimed powder with new virgin powder perfectly.

IMPORTANT – If you are new to reclaiming spent powder, a ratio of 60% virgin to 40% reclaimed powder is a good starting point.

4) Humidity Issues: If your powder’s characteristics or your shop environment causes clumping due to humidity, using fluidized hoppers will usually cure this issue if you have an air dryer attached to your shop’s compressed air supply.

With either feed system, you can be successful powder coating a wide range of substrates with multiple types of powders. If you decide on a box-fed system first, you can always add a hopper later. With most professional quality systems, a hopper can be attached right to the box feed controller and only requires a small fluidizing air tube attachment. Although it may cost a little more to have your gun configured this way, it enables a single gun to give you the benefits of both systems.

Have questions about powder coating guns? Looking to add a new gun to your existing coating operation? Feel free to give us a call. Our systems specialists will be happy to help you get the powder coating gun you need.

Using Iron Phosphate To Get A Better Powder Coated Finish

Pic for steam unit pageWe’ve talked a lot about pretreatment in previous articles: why it’s important to get your parts clean and what pretreatment options you have. But from a production standpoint, why is pretreatment important? Why add another step to your powder coating process? We’ll examine this using one of the most commonly powder coated materials: steel.

If you are powder coating, chances are that at some point you’ll be powder coating steel. Powder is easily applied to steel parts and generally provides a good finish. But what if you need the powder coating on your steel parts to last longer or to be more wear-resistant? You may be providing parts that will be subject to high-impact or are handled regularly, or parts that must last a certain amount of time. Simply applying the powder and curing the part won’t achieve the result you or your customers need. In order to get those results, you’ll need to add a pretreatment step before you apply the powder.

One of the most popular and effective forms of pretreatment for steel is iron phosphate. Iron phosphate is a conversion coating that provides a barrier against oxidation. It is most effective on bare (uncoated), clean steel.

How Can Iron Phosphate Improve My Powder Coated Finish?

Adding an iron phosphate stage to your pretreatment can dramatically improve the quality and longevity of your powder coating.

Iron phosphate provides increased adhesion. This is especially useful for slick surfaces. Iron phosphate pretreatment causes a small amount of surface material to be deposited on the parts being treated. This material is slightly textured so the powder can grip it. If the parts are occasionally bumped during their use, this improved adhesion is especially helpful because it keeps the coating intact.

Iron phosphate provides increased corrosion resistance. Most powders provide a salt-spray rating of 250 hours on clean metal, but what happens when the protective powder coating is scratched or worn? Phosphate adds a second layer of protection and can extend the salt-spray rating to 500-1500 hours, depending on the process.

How Can Iron Phosphate Be Applied?

There are a number of different ways to apply iron phosphate to your parts before you apply the powder coating.

Hand wipe: While not very efficient or consistent, there are chemicals that can be hand wiped on and then rinsed off to form an iron phosphate layer.

Hand spray: Professional quality wand systems, also known as spray wands, are very good at delivering iron phosphate chemicals to the surface of most parts. Iron phosphate works well with heat, so gas fueled or electrically heated sprayers work best. These sprayers may include pressure wash, wet steam or dry steam features. A rinse/seal step is often required as part of the process to prevent streaking or chalking that can interfere with the powder coating. Spraying is often done inside a stainless steel booth, often called a manual wash station, and/or may take place over top of a grated wash stage that allows spent chemistry to be contained and potentially recycled.

You can see a hand-operated spray wand in the video by Electro-steam below:

Dip: Heated chemical vats, also known as dip tanks, are a great way to pretreat baskets of small parts that have hard to reach areas. This often involves multiple stages performed in a series of tanks with rinse stages in between.

Automatic spray: This is generally the most effective and consistent way to apply iron phosphate chemistry, but it is also the most expensive. Multi-stage spray systems are typically part of an automated coating line where the parts travel by conveyor at a pre-set rate. A multiple stage pretreatment system can have as few as 2 stages or as many as 8 or more stages. For higher-end architectural finishes, multiple applications of phosphate create an excellent corrosion barrier and other agents in the chemistry clean the part to allow for nearly defect-free parts when powder coating is applied.

Where Can I Find An Iron Phosphate Supplier?

Search online for companies like Bulk Chemicals, Chemetall, Dubois, or Houghton. These companies and others can provide you with information about local suppliers or will have a local distributor contact you to help you select the proper chemicals.

Your local powder supplier can suggest a chemical supplier who will have products that work well with the powders you are using.

Thomas Register & related industry guides may also be able to provide you with an iron phosphate supplier. You can get a lot of information from industry guides like Thomasnet.com, but you may have to play around with your search settings to find companies that will do business on a smaller scale.

As a general rule, avoid online outlets that cater to the hobbyist and DIY markets. They may have chemical products of inferior quality or from sources that vary from batch to batch. Parts preparation is one of the most important steps in the coating process—don’t risk costly reworks by using cheap, no-name chemistry sold online by the bucket.

Have any questions on pretreatment? Need to add pretreatment to your powder coating operation? Reliant provides blast rooms and wash stations for use with your existing equipment, or we can implement your pretreatment requirements into the design of your new coating system. Whatever you need, from hand-wash spray units to fully automated wash stations, Reliant Finishing Systems can provide a quality system at an unbeatable price. Call one of our system specialists today to get started.

 

How A Powder Coating Oven Recorder Can Help Solve Your Curing Problems

Powder Coating ovens from Reliant Finishing SystemsWhether you’re just starting to powder coat or your powder line has been operational for years, you need to have an accurate picture of what’s going on inside your curing oven if you want the best results. Fortunately, there are a number of maintenance and troubleshooting tools available to help get the best finishes possible from your coating equipment. One of these tools is a powder coating oven recorder, also known as an oven data recorder, which can help identify curing problems, increase your throughput, and optimize your oven’s fuel efficiency.

When Should I Use A Powder Coating Oven Recorder?

When first starting to powder coat, it is a good idea to run an oven data recorder to determine exactly how fast your metal parts reach the proper powder curing temperature. This is important because powder companies formulate their powder to cure with specific metal temperatures and curing cycles in mind.

Depending on your market and your customer’s specifications, you may want to run a powder coating oven recorder whenever you add a new type of powder to your process. You may also want to check the oven’s performance if you are working with parts that are much heavier, thinner, larger or smaller than usual, or made of a different material (such as swapping to aluminum from steel). This is especially important if your customer has stringent finish requirements.

Identifying Powder Over-Bake and Under-Bake

The primary reason for checking your metal temperatures is to make sure you are not over-baking or under-baking your powder. Over-baking usually refers to curing the powder at higher than recommended temperatures, while under-baking means the opposite. These terms are also used when talking about the amount of time that the part surface is at curing temperature. Too long can cause over-baking and too little can result in under-baking.

Over-baking powder can lead to brittleness, flaking, discoloration (yellowing or browning), and lack of gloss. Under-baking powder can cause excessive orange peel, poor chemical resistance, lack of adhesion, inconsistent gloss, and poor resistance to corrosion. If your powder is exhibiting any of these problems, it may indicate that your oven is getting too hot or not getting hot enough. An oven recorder can help identify if your oven temperature (https://www.reliantfinishingsystems.com/powder-coating-equipment/powder-coating-ovens/) is not reaching the desired range or if there are hot spots or cold spots in the cabin that are impacting your curing results. If the temperature in the oven is not within the necessary range, or it is significantly inconsistent inside the cabin, you’ll end up dealing with curing problems even if they are not immediately detectable. A high quality powder coating oven recorder is the best tool to use when you need to identify those issues.

Understanding An Oven Data Recorder Report

There are a number of oven recorders on the market, but the most well-known brand used in the finishing industry is Datapaq. Their oven reporting software is what we will be referencing for this article. Here is a typical Datapaq graph and printed report:

Powder Coating Oven Recorder Report - Graph

Powder Coating Oven Report - Technical Readout
That is a typical report from a walk-in size batch powder coating oven from Reliant Finishing Systems. The first thing to look at is the graph itself:

Powder Coating Oven Recorder Report - Graph Close-up
The top red line shows the air temperature probe, which measures the air temperature of the oven at a specific location, usually near the part being tested. At arrow A, the air temperature rises to the 425° F set point (the temperature that the operator wants the oven to reach) and then starts idling at +/- 5 degrees. This consistent discharge of heated air allows the metal temperatures, arrow B, to rise evenly to the desired curing temperature.

If you notice dips in the air temperature line, these represent potential problems that can hurt your throughput by increasing cure times, and may reduce your overall finish quality. This is because undesired drops in air temperature may decrease the consistency of the surface temperature of the part.

The opposite problem, spikes in the air temperature, can be just as bad. Whenever your oven’s heat system overshoots the temperature you want, you’re wasting fuel. You can also end up damaging finishes that require a delicate touch. By not recognizing the way excessive air temps influence your curing cycle, you’re also probably not operating at maximum throughput.

Some common causes of poor temperature regulation by the oven’s heat system include bad temp probes (thermocouples), insufficient insulation or insulation that has settled inside panels during shipment or handling, poor air circulation through the oven cabin, improper exhaust ventilation airflow, inadequate ducting, and faulty or outdated controls.

In batch operations, employees opening the oven randomly during the curing process to check the parts can dramatically affect the air temperature inside the oven and can lead to improper curing. Obviously, opening the doors lets out hot air but the rapid drop in temperature can also cause the oven’s heat system to go into overdrive getting the temperature back to the desired range. This wastes gas. Once the doors are closed again, the overshoot can cause the oven to overheat because the heat system cannot throttle back quickly enough once the hot air is no longer escaping from the cabin.

Using Your Oven Data Recorder On An Automated Line

When testing automatic coating lines, the powder coating oven recorder travels through the oven on the conveyor. It is not unusual to see temperature fluctuations around oven openings, during direction changes near the ends of multi-pass ovens or when the recorder gets close to the output of the heat system. Adjustments to air distribution baffles, plenum discharge dampers or exhaust intakes are typical when fine-tuning an automated line.

Here is an example of an automatic line test. This graph shows some serious temperature fluctuations:

Powder Coating Oven Recorder - Automated Line Test
Although not in color in this example, the two jagged top lines indicate the air temperatures measured as the recorder moved through the oven. The two smoother lines indicate metal temperatures. You can see how the abrupt drop in air temperature affects the metal temperature graphs. This can extend the dwell time needed in the oven, requiring a lower line speed for proper curing. Left unchanged, this can cause uncured parts to reach packing. A problem of this type with a conveyorized powder coating system may be due to a faulty burner in one of the heat units or perhaps a brief burner shut-down due to a safety switch tripping.

The powder coating oven recorder report gives you a couple charts showing the temperatures achieved and the time above these temperatures.

Powder Coating Oven Recorder - Automated Line Technical Readout

The arrow shows the cure time needed for the cure temperature specified. You can get this information from your powder supplier. The times circled are the metal parts’ time above the required curing temperature. Since these times are greater than the specified duration at the curing temperature, the parts should be fully cured when they exit the oven. If they do not reach the specified time at temperature, you’ll probably have to turn up the temperature of your oven or increase the dwell time.

Different metal thicknesses will affect your cure temperatures and times. If you are curing thin and thick parts at the same time using the same time/temp combination, you can possibly over-bake the thin parts–causing discoloration or reduction in gloss. Try to batch similar thicknesses of parts whenever possible. It’s also a good idea not to mix aluminum, stainless and mild steel parts if possible because they can have different curing characteristics. Even if you don’t use a data recorder, make sure you check the finishes you are getting with samples of all of your common parts when setting up your oven. Don’t let lack of attention to detail during set-up rob you of future profits.

When To Call In The Pros

Many powder providers will be glad to run a data recorder through your oven and share the information they discover. This allows them to help you get the best results from their products. It also gives them a chance to justifiably blame bad finishes on faulty or poorly calibrated equipment.

Larger production facilities and high-end job shops may have their own data recorders. These are usually stored and operated by finish line managers or facility maintenance technicians. In smaller shops, owners may have to request a line audit from a service company.

No matter who runs the data recorder, adjustments to the oven should usually be made by factory-authorized technicians. Shops with large coating lines may have in-house personnel trained to repair and adjust their ovens by the manufacturers or providers. That situation is uncommon, and most powder curing ovens are supported directly by the oven manufacturer, an equipment distributor or a specialized service company. When it comes to tuning your oven, we recommend that (whenever practical) you work with the company that built it.

Your powder coating oven should be started and calibrated by an experienced professional. Ideally, you should run some test parts with a data recorder early-on. After you’re in production, it is a good idea to check your oven quarterly or whenever you have a new part with significantly different thicknesses or geometry. A properly cured part is essential for your customers’ long-term satisfaction and will prevent costly returns and reworks.

Need your oven checked? Reliant Finishing Systems offers a wide array of services, including oven data recording, technical support, line audits and other troubleshooting services. Give us a call today.

Powder Coating Special Effects Can Give You Outstanding Results

Powder Coating Special Effects

Examples of powder coating special effects, provided by Espo’s Powder Coating.

As you know, powder can give you a more vibrant finish that lasts longer than traditional wet paint, and now it can rival wet paint’s ability to create jaw-dropping special effects. Many people, including coaters who have worked exclusively in a production environment, are sometimes unfamiliar with the effects that can be achieved with powder coating. In this article we’ll discuss some of the amazing powder coating special effects you can achieve with today’s powder coating technology.

Difference Between Powder Coating & Wet Paint Effects

While powder coating special effects are similar to wet paint, there are some key process differences between the two applications. Wet painters frequently use multiple layers of paint that are combined to create depth and brilliance. Liquid painters also use products that have specialized metallic or mica pigments to reflect light. These products can be applied in separate coating steps to create a custom look.

Powder coating special effects works in a similar fashion, but you have to cure, or at least partially cure, each powder layer before applying the next coat to achieve the correct results when attempting process special effects. Although this can be time consuming, you can get amazing results from multi-step effects like candy-coats and two-tone finishes.

Like certain wet paint products, there are powders that can create one-step special effects. Popular one-step effects include river textures, wrinkle textures, hammer-tone, veining, glimmer, and even holographic finishes. These one-step finishes just need to be applied carefully and evenly to your metal surface and then cured per the suppliers’ recommendations.

Process Powder Coating Special Effects

A process special effect is a special powder coated finish that can only be applied with multiple powder applications and curing steps. This includes candy colors and two-tone finishes.

Candy Colors, also known as candies: These products create finishes that have incredible depth and usually provide bright, dramatic colors. They are typically applied in 3 steps: a metallic primer provides the background, then a transparent but colored base coat is applied, and then a clear gloss topcoat completes the effect. Each coat is cured individually. The final clear is not always required, but will add durability and protection for exterior parts.

Prismatic Powders has a great example of a header done with one of their finishes here: http://www.prismaticpowders.com/gallery/detail/8296/Prismatic-Illusion-Violet-with-Clear- Vision-Top-Coat/

Two-Tone Finishes, also known as bi-tone or cut color:  A two-color finish that requires masking, and requires skill and patience to achieve the desired result. Masking a powder effect is challenging and you need to use high temperature tape in order to keep a clean line between colors. Using two colors that are intense and dramatically different will give you the best results because the second color coat usually has to cover the first coat. It can be done with some transparent coatings, but you will have to carefully plan your finish order. Like with anything you powder coat, doing small test pieces is always recommended before finishing large production pieces.

TIP: When removing high-temp masking tape, try to do it when the part is around 180° to 200°F. If you wait until it’s cooled down to room temperature it can leave flakes. If you pull it too early and the part is still near curing temperature it can pull strings of applied powder off of the surface of the part. A hand-held heat gun and a good quality IR thermometer (temp gun) can help with this custom technique by heating the part if it gets too cool and preventing damage to the finish.

Tom Esposito of Espo’s Powder Coating did a fantastic blending job using no tape to produce this custom frame finish: Powder coating special effects examples from Espo’s Powder Coating

One-Step Powder Coating Special Effects

As opposed to process effects, one-step effects are sprayed and cured just like conventional powder. All major powder manufacturers have special effect finishes that can be sprayed on in one step and then cured. The most common powder coating special effects are those that create textured finishes. Wrinkle and river are some of the terms used to describe the visual effects these powders create.

It is important to note that these powders must be mixed consistently to achieve consistent results. Conventional vibratory box guns are not as effective as hopper style guns that feature hoppers with fluidizing membranes. These hoppers constantly mix the powder with air, while vibratory box-fed guns may separate the heavier particles from the lighter ones due to agitation (think of the way gold panning works). Light textures usually work fine, but the heavier veining effect powders with multiple metallic or mica flakes can give disappointing results when sprayed from a box hooked to a vibratory gun system.

Vein/River Texture: Vein textures are quite dramatic and can give a unique look to your parts. They are often used for electronic enclosures, interior industrial applications, and many interior furniture components. Be careful selecting a vein for an outdoor application. Because of the nature of the veined powder, it can cause different finish thicknesses across the part and may compromise the salt-spray durability of the powder. Unless a texture effect powder product specifically states that it is for outside use, consider it as interior-use only.

Here is a Cardinal Powder chart that shows some different vein effect powders that are available: http://www.cardinalpaint.com/products/productcat.php?pcid=2&cctid=12

Metallics: True metallics come in two qualities: bonded and unbonded. Bonded metallics have a little bit of clear powder attached to the metallic powder particles and may be suitable for one-step interior applications. Unbonded metallics need to be coated again with a clear topcoat to protect the metallic particles from oxidization. Some bonded metallics also need an extra clear coat for exterior durability.

TIP: Metallic effect powders sometimes need different gun settings due to their conductivity. If you get weird patterns when spraying metallics, turn down your kV setting to the 20 to 40 range and see if that helps.

Micas: These specialty powders create finishes that look similar to metallics but are more pearlescent or opaque. They can be used on interior or exterior parts and are typically cheaper than the bonded metallic effect powders.

Hammer-Tones: These powders usually combine the river effects with pearlescent mica pigments. Consistent film thickness is important to maintaining a consistent hammered finish appearance.

As you can see, powder coated finishes can offer impressive custom looks. Modern powders can produce a wide range of special effects that can take your project to the next level.

Have you used any of these powder coating special effects before? Especially proud of your work? Even if you don’t use equipment from Reliant Finishing Systems, send your pics to info@reliantfinishingsystems.com so we can share your work with others who have an interest in powder effects.

You can also share them on our Facebook page at www.facebook.com/reliantfinishingystems

Powder Coating Gun Comparison

HGS_3903_CropWhen you’re setting up a manual coating line, one of the main decisions you’ll have to make is which powder coating gun system best complements your operation. To help you make your decision, we’re taking a look at the top three manual powder guns on the market – from Wagner, Gema and Nordson – to see what each one has to offer.

Disclaimer: For the purpose of this article, we’ve limited our reviews to these three manufacturers. While there are many other powder coating guns out there, these three brands produce the best available guns in the powder application industry. Since your coating success is ultimately determined by the quality of the finished product, having a powder coating gun that can give you consistent and professional results is vital to your operation.

Powder Coating Guns From the Big Three: Side-By-Side Comparison

All three gun systems are well made and have great track records for performance and reliability, but they have subtle differences.

Here’s a simple chart with some key specifications so you can see a side-by-side comparison. The units listed are the basic vibratory box-fed models without any customization.

Wagner Sprint X Gema Optiflex 2 Nordson Encore XT
Gun Weight 490g 520g 475g
Max Powder Output 450g/min 395g/min 300g/min
Price (approximate) $5,500.00 $6,500.00 $6,000.00
Presets 50 20 20
Warranty 2 years in a one shift operation 5 years 5 years unit/ 2 years cable
Special Operation Mode PCC mode AFC mode

Wagner Sprint X Powder Coating Gun

Manual Powder Coating Gun From Wagner

 

The Wagner Sprint X is the lowest priced of the brand name, premium quality manual application units. Because of its lower price, the Sprint X is extremely popular with first-time buyers, but the consistent results it provides makes it a top-choice for established operations as well.

The warranty is adequate for most buyers and Wagner is noted for having common repair parts available on short notice. Like previous Wagner models, the Sprint X includes both upgradability and backwards-compatibility features that the other units can’t match.

Wagner introduced a new controller design a couple years ago with all of the key functions tied to an intuitive rotary dial. It provides a great deal of flexibility for different types of powder and varied coating situations.

It’s very easy to assemble the gun, plug in the cables and hoses, and start shooting powder using the three main presets. However, if you like to have lots of custom settings for different powders and coating situations, you can program up to 47 more settings into the unit’s memory. With 50 total presets, the Sprint X has more than twice as many available settings as the other guns in this review.

The 450 gram-per-minute application rate is also the most powder output of any of the units reviewed. Although the unit is capable of finely-controlled powder application, it is a natural choice if “blow and go” is your preferred method of powder coating.

Wagner introduced a new gun several months ago with the Sprint X designation. The result is a smaller and lighter design, and you can adjust powder volume on the gun without having to walk back to the main controller. Because of the change to the lighter design, the current gun is a bit more fragile than some previous models. Try not to drop it or over-tighten its plastic screws when taking it apart for inspection or component replacement.

Gema Optiflex 2 Powder Coating Gun

Manual Powder Coating Gun from Gema

The Gema Optiflex 2 is the most expensive of the three gun units reviewed, but that price includes incredible durability backed up with the best warranty provided by any of the major brands. If you are looking for a powder coating gun that will work – and work for a long time – then the Optiflex 2 is a great choice.

The Optiflex 2 powder coating gun is very easy to pick up and start coating with. It is easy to assemble and sprays excellently out of the box. The pump picks up the powder smoothly and has little to no built-in surge when triggered. In our experience, the Optiflex 2 sprays the “softest” of the three units. This can help with multiple coat situations, like when you are spraying candy colors.

The system has a total of 20 presets, which is adequate for the vast majority of coaters. The gun is a bit heavier than the other models reviewed, but it is robust and easy to use. Like the other guns, it has limited controls built-in.

When needed, the 395 gram-per-minute output is more than enough for most applications. The PCC mode helps with Faraday cage areas and tight corners by pulling some of the free ions out of the charge field. This allows operators to get closer to the part in difficult areas and perform detail work without having to change settings.

Nordson Encore XT Powder Coating Gun

Manual Powder Coating Gun from Nordson

The Encore XT is the mid-priced powder coating gun in this review. We were pleasantly surprised by the price since Nordson has historically been the highest priced manual gun option on the market. Nordson is very well known for their high-end automatic guns and spray systems, and we were glad to see their latest model meet their high-quality standards while still being very price-competitive.

The Encore XT model features 20 presets, allowing you to customize up to 17 settings that be saved by the controller. As an added convenience, you can cycle through the settings on the gun itself so you don’t have to walk back to the main unit to make a change. The gun is also surprisingly light and easy to wield.

One thing to note is that the maximum powder output of the Encore XT is a good bit less than the other models. This system seems best suited for skilled coaters who appreciate finesse.

With that said, the Encore XT features an AFC mode. This helps new or less skilled operators by adjusting the electrostatic settings automatically using feedback based on the gun-to-part distance. This mode is especially helpful when dealing with tight areas and Faraday cage issues.

Summary

After carefully reviewing each model, all three of these guns would be excellent choices for any manual powder coating operation. Because they have fairly comparable price points and similar features, here are our recommendations based on our most common customer needs:

For price sensitive buyers, the best option is the Wagner Sprint-X. The Wagner powder coating gun  is the lowest priced model with the most affordable replacement parts.

For maximum versatility, pick the Wagner Sprint-X . With more available setting and much more powder output, the Wagner gun is a great choice for operations coating many different types of parts.

For high-end performance (for high-end fabricators or automotive/custom work), the Gema Optiflex 2 provides a softer spray and a PCC mode that allows you to easily coat items with odd shapes.

For longevity, you can’t go wrong with the Optiflex 2. Gema has a great industry reputation for the durability of their powder coating guns, and the Optiflex 2 will last you for years. The warranty is also the best in the coating gun industry. However, the replacement parts are more expensive, so keep that in mind if price is a factor.

If you are planning on expansion, then the Nordson XT is the way to go. If you want to upgrade to an automatic line in the future, or you’re adding a batch system to supplement an existing automated line, Nordson’s Encore XT is a great complement to their well-respected Encore automatic guns. The parts are fairly interchangeable and your operators will not have to learn a new control system.

No matter which gun you choose, any of the three manufacturers we’ve reviewed will provide you with high quality equipment that will produce a finish you and your customers can be proud of.

Planning Success For Your Automatic Powder Coating Line

Best Powder Coating GunsWhether you are replacing your overworked batch system or bringing your power coating in-house, you’ve decided that a new automatic powder coating line is the way to go. You’ve done the homework and determined a new line will increase your productivity and save you thousands of dollars this fiscal year alone. You’ve placed your order and now all you have to do is sit back and wait for the new equipment to be installed, right? Wrong.

Now is the time to prepare for success with careful planning before the equipment arrives. When putting in a new automated line, there are three key things you can do to make sure you get the best outcome:  Pay attention to details, make good use of outside support and understand the challenges a major facility change may have.

Pay Attention To The Fine Details

Assess all of the factors that could impede the delivery, installation and start-up of your new automated line. Make sure you have the following items or answers before finalizing your plans:

Get detailed drawings of the proposed equipment and determine where everything will be placed.

In the preliminary stages of a project, a rough drawing is used to sketch out a plan for the automatic powder coating line. Now is the time to tighten up the drawings and look for potential obstacles that could impact the location or performance of the equipment. We recommend identifying anything in the factory that might impinge on the equipment – electrical service, air lines, HVAC equipment, sprinklers, ventilation ducts, drains, low ceilings or support beams. You also need to scout for potential facility-specific problems like having sanding or welding stations too close to the coating operation. These areas, which can generate substantial dust and debris, can contaminate your coating area and keep your new line from being successful.

When planning for powder coating, make sure you understand spray & cure times for parts. You’ll need to know how long the cool-down times will be and where the parts will be stored while cooling. You’ll also need to know where the coated parts will be packaged and the untreated parts will be stored. Plan the traffic flow in the facility so you can move your parts safely throughout the pretreatment, coating, curing and packing processes.

Set the date with a project timeline.

Like detailed drawings, a detailed time line is essential for successful line implementation. Allow for flexibility, but set specific target dates when a certain task or component needs to be completed. Make sure that all contractors have access to the initial timeline and have signed off on your targets. If the timeline has to be revised, make absolutely certain that all contractors are aware and have signed off on new deadlines. Remember that if you set unrealistic goals for the performance of your contractors, you’re setting everyone up for failure.

Set a change order budget on the front-side and stick to it.

Complications arise during large finishing line installations. They can lead to unavoidable changes to the scale or placement of the equipment. Often these changes must be performed on the fly. Changes can also lead to staggering expense increases if not carefully managed. Set a realistic change order budget that cannot be exceeded. Make certain a change is really necessary before instructing the contractor to implement a change order, but don’t let good advice go unheeded just because it may increase the installation cost. A wise but costly decision made during equipment installation is almost always better than being stuck with a system that doesn’t work as well as it could.

Plan for BIG success.

Before issuing the first PO, address your potential production needs for 5+ years down the road. Make sure the line is expandable or that you have a plan in place should you experience explosive growth.

Utilize Your Assets: Outside Contractors, Consultants & Inspectors

Due to the size and scope of adding an automated line, you will have to employ or interact with a number of outside contractors to get your equipment up and running quickly.  These are the most important people you will be working with: 

Project Manager

Since this is a complex construction project, there needs to be a project manager who is in charge of all the details.  A project manager can help set realistic time lines for when components of the line should be delivered and installed. While the project manager can be someone in-house (the finishing line manager is the most common candidate), it is more likely that someone from the equipment supplier should be managing the integration of the equipment into the facility. The project manager should be scheduling meetings with all the contractors and suppliers to ensure timely installation and then providing regular reports on the installation progress.

Consultants & Industry Experts

Getting the advice of a true expert can be invaluable when making a major investment. All established providers of automated coating equipment will have experienced technical specialists on staff, but you may want to get a second opinion from a third-party expert before finalizing the layout, purchase and installation of your new coating line. Finishing consultants are not hard to find, and may be a good investment if you are unsure how to proceed.

Powder & Pretreatment Suppliers

Keep your pretreatment and powder suppliers in the loop during the construction and installation process. Consult with them on any line changes or change-orders, especially if the changes would reduce process times, since cure times and cleaning/pretreatment dwell times are extremely important for a consistent finish. If the line changes too much in scale or there are unplanned changes to the line speed, it can negatively affect the quality of the finished product.

Code Inspectors

If you want your installation to go smoothly–no matter where you’re located–you’ll need the cooperation of the local code authorities. Make the building inspector and fire marshal your friends before construction. Reach out to city water officials and state environmental inspectors; informing them of your project beforehand allows you the opportunity to educate them on any unusual processes that they may not be familiar with before permitting deadlines are reached. Your chemical and powder suppliers can help, as can code compliance consultants. Interacting with local Authorities Having Jurisdiction (AHJs) during the planning stage can pay huge dividends down the road.

Be Prepared For Facility Changes & Possible Challenges

As the construction of your new equipment draws to a close, your facility will be going through a learning period as your staff integrates new processes into their workflow. Here are some common issues to be aware of:

Production Learning Curve

Plan for less efficiency at the launch of your new coating operation due to material adjustments, reworks, and employee learning curve. While powder coating is much easier than applying wet paint, there needs to be grace periods as your coaters learn how to consistently prepare the parts, apply powder to the correct thickness, and get it cured properly without damaging the finish. You’re going to encounter mistakes as your personnel learn to operate and service the equipment, so keep this in mind as production begins.

Schedule Your Preventative Maintenance From The Very Beginning

Make sure you have an employee responsible for a preventative maintenance plan and make your employees stick to it. Your maintenance schedule should include routine cleanings and filter inspections, chemistry checks and gun testing, as well as more involved tasks like burner inspections and bearing lubrication. Review your maintenance routine every Friday or Monday (or both) until it becomes a habit. Adjust service intervals as necessary, but always err on the side of caution. It’s better to change filters a little too soon or spend a little more time cleaning your guns than to rework an afternoon’s worth of bad parts.

Quality Assurance Program

You will need a QA inspector that has the authority to reject defective finishes. Review your QA standards often to make sure they are not too strict or too lenient. Ensure employees are properly trained on testing the finish and that they understand the standards they are expected to meet. When changing to new powders or chemicals, hold a mandatory orientation session where workers can ask questions and experiment with new materials and processes.

Realistic Expectations

No matter what you do, there will be complications. Unexpected construction delays, paperwork hassles, defects from the wrong settings or under-trained employees, costly chemical adjustments, and unanticipated issues of all types can impact your new line every step of the way. The good news is that most of these issues can be quickly solved – if not prevented outright – by careful planning, good advice and attention to detail. Once your new line is installed and debugged, you’ll be glad you made the decision to upgrade your capabilities.

Deciding If An Automated Coating System Is Right For Your Operation

Automated powder spray boothsNow that you understand the selection process for a batch powder coating operation, it’s time to determine if a batch line or automated coating system is the right solution for your operation.

Are you launching a large coating operation from scratch and can’t decide what type of line will work best? Have you been powder coating with batch equipment but need to increase throughput? Perhaps you’re bringing powder coating in-house to finish the products your company manufactures, but you’re not sure how to do it. The decision to install an automated finishing system is a considerable one. Before you make the investment, you need to ask yourself if an automated system is right for your company’s operation style and daily coating requirements.

You Need To Powder Coat More Items Per Day

The number one reason to move from a batch line to an automated coating system is to increase throughput. If your business needs to produce a high volume of powder coated parts on a daily or weekly basis, and these parts are somewhat similar in size, you should consider installing an automated line. Since automated coating is a continual process, you’ll almost always be able to coat more parts in a set period of time than if you coated them manually in small batches. But, many problems with throughput can be resolved with less expensive batch equipment.

If you already have a batch system in place, and your production quota is exceeding your current throughput, determine if there is a bottleneck slowing down your operation. If your bottleneck is at the cure cycle, can you add another oven (https://www.reliantfinishingsystems.com/powder-coating-equipment/powder-coating-ovens/) to improve your capacity? If you’re losing time loading and unloading the parts on racks, is it cost effective to add more employees or build more racks? Evaluate your current system and see if you’ve done all of the simple and affordable expansions to your current operation. Bring in a consultant if you need expert advice. Sometimes a simple fix, like adding another gun or hiring an assistant for your coater, can significantly increase your throughput. If you have already upgraded your batch system and solved all of your bottleneck and speed issues, investing in an automated line is the next logical step to increase production.

You Need To Increase Your Powder Coating Consistency

If you need stringent quality control, an automatic line provides repeatable and consistent finish quality that is tough to match with a manual coating operation. Automatic gun systems from companies like Wagner, Nordson and Gema can be programmed to apply specific amounts of powder at just the right setting for best coverage. The process can be repeated automatically for each part. As long as the equipment is properly maintained, the results are ideal and consistent. If your current manual approach is too erratic because your coater is having trouble keeping up, or your customer’s finish requirements are very specific, an automatic system can provide highly consistent results when properly operated and maintained by skilled employees.

Your Parts Must Meet Stringent Coating Specifications

There are several common finishing specifications that you may be asked to meet in order to capture and retain a client’s business. Some of these finish standards require you to employ a specific pretreatment process to achieve acceptable results. Others may simply require finished parts to pass a durability test. Depending on your industry or your end-customer uses, your powder coated parts may need to meet national specifications before they can be used in the field.

One group of standards includes the AAMA (American Architectural Manufacturers Association) 2603, 2604, and 2605 aluminum specifications. Here is a link to a chart with a comparison of the three standards:http://www.aamanet.org/upload/file/2603-2604-2605_Comparisons_4-6-11.pdf

Each standard requires more extensive pretreatment and powder quality processes than the lower one. For example, the 2603 specification can be passed by a manual operation, but the 2604, and definitely the 2605, require an automatic pretreatment process (usually of 4-5 stages or more). Dip tanks can work for specialty parts, but if you are looking at part counts of 1,000-2,000 per day, manual solutions are just not practical. Hanging parts on an automatic line is the most efficient way to prepare large quantities of them consistently. Knowing your production requirements and parts specifications makes your system decision process much simpler.

You Need To Reduce Labor Costs

Cost management is an integral part of efficient production. Reducing labor costs on a per part basis can propel a company forward. Automatic lines can almost always reduce the amount of labor required when compared to their manual counterparts, but there is a minimum of how few employees it takes to run an automatic line.

Typically in a small automatic line you will need someone to load the parts, another person to run the automatic spray booth and perform manual touch-up of problem areas, someone to inspect/unload the parts, and a finish line manager who makes sure the employees are doing a quality job and the equipment is running properly. At least one person needs to know how to adjust the pretreatment section and how to maintain the equipment so that the line remains operational. A minimum of 3-5 employees is recommended for even a small automatic line.

You Don’t Need A Great Deal Of Versatility

Automated lines are sized based on the largest, densest parts that will be coated. The pretreatment and curing processes are often calibrated to get premium results with specific parts. Shops that routinely deal with parts that are in the same general size and density range are the best suited for automated coating lines. If you have parts that are substantially different in size and density (such as 10’ long sections of 3” wide railing, heavy 15” by 15” by 20” machine parts and thin 4’ by 4’ by 4’ pre-assembled frames), an automated curing line may not be practical. Although a single automated system can be set up to accommodate all of these parts, the costs to buy and operate it may be prohibitive.

The other consideration that may make an automated system impractical is if your company does not operate in a fairly consistent way from day to day. Specifically, if jobs are frequently being leap-frogged in line ahead of other work or your operating hours vary widely from day to day. It takes a while to get an automated system up and running, and it takes longer than batch equipment to shut down at the end of the day. Shuffling parts around, changing set-ups and re-starting the line can quickly offset the benefits that make an automatic line effective. Automated powder coating lines get the best results when they are used in a consistent and routine manner.

Comparing the Benefits Of An Automated Finishing System Versus A Batch System

If you can satisfy your production and cost requirements with a batch system, you are better served with the flexibility and lower cost of a well-made batch system. However, if your production quotas or part specifications require it, an automated line may be the obvious solution. We always recommend that you have a clear understanding of your production goals before making a system purchase.

If you’re still debating whether you need an automated powder coating system, here’s a summary of  the benefits and drawbacks of an automated line, as compared to a batch system.

Automated Finishing System Benefits:

  1. More parts per shift
  2. Repeatable finish quality
  3. Better pretreatment options
  4. Reduced labor per part
  5. Efficient use of labor due to constant process
  6. Lower powder cost per part  (especially if reclaiming powder)
  7. A single automated line is more energy efficiency than multiple batch appliances
  8. Consistent, high-end finishes are possible with a quality system

Automated Finishing System Drawbacks:

  1. Less flexibility: Parts have to be hung on line in a specific way. Parts are also limited to a certain height, length or width. Changes to any aspect of the coating process can cause costly downtime.
  2. Substantial cost increase: The capital equipment cost is significant greater, usually 3-5 times that of a comparable batch system
  3. Color changes are more difficult: Reclaim booths are usually for just one color unless you buy a cyclonic or equivalent type powder recovery system. Even then, changing colors is not easy in a reclaim operation. A spray-to-waste booth positioned in line immediately after a reclaim booth is not uncommon, but this increases the total equipment cost as well as the footprint of the installed equipment.
  4. Increased training expense: Automatic equipment requires better educated, well-trained employees to operate it. Employee retention is important after they have been trained because of potential downtime when dealing with new hires.
  5. Increased maintenance: Automatic lines must be vigorously maintained or they won’t function correctly. Poor maintenance practices can lead to lost production time and wasted labor waiting on the line to be fixed.
  6. A problem anywhere is a problem everywhere: Unlike batch systems, where the processes are isolated, a failure in one area of an automated system causes a backlash throughout the line. If a coater has a serious problem in the powder booth of a batch line, other parts can still be prepped and cured while the problem is addressed. If there is a problem in the spray booth of an automated line, the other processes will also come to a halt as soon as the conveyor is stopped.

Careful cost analysis should be performed before deciding on an automatic finishing system. Automatic lines can be very beneficial and improve profitability but their functionality is very specific. They are simply not as versatile as manual batch systems. Pretreatment stages, amount and type of powder to be applied, curing schedules and cool down times must all be calculated before the equipment is manufactured. If you’d like to learn more about the various types of powder coating media, the common steps in chemical pretreatment, and other helpful information that must be taken into account when specifying an automated system, check out our other articles by visiting our Resources page.

Choosing Your Powder Coating Equipment

Custom Coating EquipmentIn previous articles, I have talked about selecting a system or process before choosing your powder coating equipment. After you have established your process and have a rough idea of the timing of each step, you can select equipment to meet your production requirements.

Setting up a powder coating shop involves many variables besides powder or pretreatment. The size of part to be coated, layout of shop to be used, labor, parts per day requirement, staging of racks or parts in process, loading area, and unloading area are all factors that must be addressed when designing a work area.

What’s The Largest Item You Will Be Powder Coating?

The first factor to consider when sizing your equipment is the size of the parts you’ll be coating. Determine the size of the largest part you will be routinely powder coating and use that as the base size for your equipment. If your typical part is small, instead decide how many you want to coat at one time and how large the rack(s) will be to accommodate your throughput.

Once you have those measurements, you’ll need equipment that is appropriately sized for your application. For the powder spray booth, typically you will need 2-3 additional feet around the part so the operator can easily apply powder to the part without walking or spraying outside the booth.

The powder oven (checkout one from Reliant) can usually be smaller than the booth, but you still must account for the size of the rack(s) in the oven. If you are using multiple racks, you will want enough space inside the oven so the racks do not bump against each other and the doors can still be completely closed.

For example: If your rack of parts is four  (4) feet wide, five (5) feet tall, and six (6) feet long, you will want an eight (8) feet wide by ten (10) feet long booth with at least an 8 foot ceiling. This will give you two (2) feet all the way around the part, so the operator does not have to move the rack while powder coating. The additional height above the rack will allow the powder to go around the parts and not get deposited on the ceiling lights. This same rack can go in a six (6) feet high, six (6) feet wide, and eight (8) feet long oven. The smaller oven helps to bake the parts more efficiently.

Shop Workflow and Layout

Exterior dimensions of the equipment need to be known so that you can plan a good shop layout. Make sure you have enough room in your shop for not only the equipment, but adequate turning space for your parts or racks, and staging areas for parts moving into and out of your pretreatment, coating and curing areas.

Powder Coating System Layout Sample

Sample powder coating system layout with curing oven, powder booth, blasting booth and wash area shown.

When laying out your shop, be certain you have enough space to satisfy your local safety code requirements. Code varies from place to place (and I strongly encourage you to make the local code inspector your friend prior to a large equipment purchase) but a good rule of thumb is to make sure all components are at least three (3) feet away from each other and the shop walls or structures. Roof height is also an issue. You want at least three (3) feet clearance above the components and you do not want sprinkler systems (unless rated for 350F) or air hoses running over your oven. Your roof supports can sometimes be closer, but you will need to determine that with your local code authority.

Walkways, emergency escape routes, and staging areas for racks are other factors to consider when planning your shop layout. Be sure and have good access to utilities such as gas and power for the booth and oven. Water should be run to the area where you plan to have pretreatment and cleaning processes. Drains or water capture alternatives are also important; depending on your finishing process, you should plan these well in advance.

How Many Parts Per Day Do You Need To Powder Coat?

Another key factor for equipment planning is production requirements. In a batch system, you are only as efficient as your slowest stage. Typically this stage will be cure time.

Since the average cure time for polyester is metal temperature reaching 400F for 10 minutes, this usually means a 20 minute dwell time for gauges around 18-16 gauge. Quarter inch angle iron can take 30-40 minutes and some castings can take 45-60 minutes to reach the part temperature of 400F for ten minutes. Of course, powders vary in cure cycles as do metals in time it takes to reach their required cure time. I recommend running an oven recorder regularly to set your dwell times to reach optimal cure times.

Figure out your slowest cycle time, I’ll assume curing, although it could be metal preparation. A typical cycle time would be 20 minutes. That gives you 24 cycles times in an 8 hour shift, if you run everything at 100% efficiency. For example, if you do muffler tubes and can rack 100 tubes per cycle, your maximum daily production rate will be 2,400 muffler tubes. If you need more production, you can add more ovens till something else becomes your lowest cycle time, or bottleneck. When labor cost starts to increase too much by adding multiple ovens or booths, then you can look at automatic solutions.

Many beginning powder coaters think of automation right away, but I would almost always recommend trying to achieve your production goals with batch systems first. That way you learn the process and what it takes to achieve a good finish. Batch systems also give more flexibility and adjust to different powders, metals, thicknesses, and process better than automated lines. Now if they have to have 10,000 parts a day, automation is probably the way to go.

Selecting The Right Powder Coating Equipment Checklist

Purchasing the correct equipment can be a little overwhelming, but by identifying the key factors, the equipment purchasing decision gets easier.

Preparation: Am I blasting and/or washing? If yes, then you need a blast booth and/or wash booth.

Preheat/Dry: Do I need to preheat my parts due to pretreat drying, process or out gassing? If yes, then decide whether an extra oven is necessary or if you have capacity with your cure oven.

Size Of Parts And Racks: This determines the size of your equipment and necessary workflow requirements.

Available Area In Shop: This determines the amount of equipment you can fit or whether you need additional shop space.

Parts Per Day: Determines the amount of booths and ovens you will need to achieve your current and future production goals.

 

Knowing Your Powder

Powder For Powder CoatingNow that we have discussed the advantages of powder coating and the benefits of bringing your coating system in house, it’s time to talk powder. There are a number of different kinds of powder available, and selecting the right one is a key component to your finishing operation.

 

The Base Powder Coating Resin

When we talk about powder quality and performance, we always reference the powder’s base resin. The base resin is what the powder is made of (polyester, epoxy, etc) and will greatly impact two things: the final coating quality and your pretreatment process.

Depending on the specific performance criteria of your customer or your parts, there are multiple base resin qualities to be considered. We always recommend researching your requirements and deciding on your powder quality prior to purchasing equipment so that you don’t buy the wrong size oven or the wrong pretreatment solution.

Polyester Powder Coatings

The most widely used base resin for powder coating is polyester. Polyester has great exterior durability, good hardness, excellent chemical resistance, and is fairly easy to cure. Most start-up powder coating operations use a form of polyester due to its performance, affordability, and ease of application.

Polyester powder comes in many varieties. A couple of the most common are:

Low-Cure: Can be cured at 325F-350F. Lower cure temperature helps with some under powered ovens or quick cure applications. The downside of low cure is shelf life reduction and reduced performance.

Super-Durable: These polyesters have specific resins for longer retention of gloss and improved color fade resistance. They are used for exterior equipment applications such as high end tractors and trucks. They also use specific pigments that are designed to be UV ray resistant. This improvement comes at a higher price and may have tighter application tolerances.

TGIC-Free: Most polyesters are made from a TGIC resin. Certain architectural specifications require TGIC-Free polyester powder coating. They are usually a little higher in price and have tighter application specifications, but they may be less sensitive to cross-powder contamination.

Example product sheet: http://www.tcipowder.com/pdfs/product-literature/tru-illusion-product-flyer.pdf

Hybrid Powder Coatings

Hybrid powder coatings are a mix of polyester and epoxy resins. Most of your special effect coatings are this quality due to the pliability of the formulation. River textures, metallics, base coats, veins, and other effects are possible with this quality of powder. They are primarily for indoor applications since the epoxy part can degrade with exposure to UV radiation. Some formulations allow polyester clear coats to be applied after the hybrid coating for exterior quality. Hybrids are usually less expensive than polyesters and usually have lower cure temperatures.

Example video: https://www.youtube.com/watch?v=d1cIz1pj_yI

Epoxy Powder Coatings

Epoxy powder coatings are used for parts that need superior chemical resistance but will not be exposed to sunlight. Under hood car parts, pipelines that are buried, and interior lab components are some common applications for epoxy powder coating. Powder primers are typically made from epoxy resins due to their affordability and extreme salt-spray performance. They usually are cured at lower temperatures than polyester and can be partially cured in the case of primers.

Example data sheet: http://www.tiger-coatings.us/fileadmin/user_upload/downloads_us_new/product-data-sheets/tiger-drylac/interior-applications/TIGER_Drylac_Series_69_Interior.pdf

Urethane Powder Coatings

Urethane powder coatings are used for high end parts that need great flexibility and exterior sunlight exposure performance. Typical applications for urethane powder coatings are marine exterior components, tight tolerance automotive parts, and impact-resistant surfaces. They are usually much higher in price than typical polyesters and are for specific applications that need them. Application is fairly normal with cure times similar to polyesters.

Example data sheet: http://www2.dupont.com/Powder/en_US/assets/downloads/tds/Channel_Green_AFG507S7.pdf

Kynar™ Powder Coatings

Kynar™ powder coatings are used primarily in aluminum applications on the outside of high-rises or anywhere that requires a ten year warranty against gloss loss and color fade. They are extremely expensive and difficult to apply correctly. They require specific pretreatment and applicators must be certified by the powder supplier with extensive testing be fore the powder coater is even approved to use the powder.

Example data sheet: http://www.ppgideascapes.com/getmedia/7ea7c346-46ac-4572-a91a-1123dcbc1554/DuranarPowder.PDF.aspx

Choosing The Right Powder For Your Process

Using this guide will help you determine the powder you need for the most common powder coating applications. However, if your process is very specific, you may also use acrylic coating, high-temp powders, and/or blends of the above resins for certain specialty purposes. Again, we always recommend researching your customer’s requirements (longevity, gloss, salt-spray resistance, etc) prior to making your powder or equipment purchase as it will determine the cure time, pretreatment required, and the application amount of the specific powder.

Once you’ve determined exactly what sort of powder and pretreatment you need, it’s time to plan your powder coating system. If you need assistance in planning please give one of our systems specialists a call.

Cleaning & Pretreatment Primer, Part One

Get_better_powder_coating_results_with_clean_partsBefore the first coat of powder ever gets applied, you have a decision to make: “How are you going to prepare your metal?

To get the best powder coating results, the surface you will be coating must be clean. Depending on the quality and type of metal, there are different levels of cleaning and pretreatment for powder coating to consider. You should also account for your customer’s requirements and how long the part should last in the field.

With all of these factors you may be wondering where to start, but it is as simple as asking:

What’s the best way to clean my metal?

What kind of pretreatment should I use?

What requirements does the finished product have?

The Best Ways To Clean Your Metal Surfaces For Powder Coating

First, determine what you’ll be coating the most often. If you are coating sheet steel, for example, you will usually only need light oil cleaning. Angle iron or castings often need sand/shot blasting to remove scale and surface rust. Aluminum is prepared differently than galvanized or regular steel; the oxidation layer of aluminum must be removed, which requires certain chemicals that provide a good etched layer for paint adhesion. Identifying which type of cleaning is right for your process is the first step in long-lasting, quality results.

The most common types of metal cleaning are:

Blasting. Blasting with sand or shot is a great way to clean up metal scale, laser scale, rough welds, or heavily rusted steel. Blasting is also used to strip off previously coated metal for refinishing. While blasting smooths out a lot of surface defects in raw metal, it does not fully clean the metal of oils or other contaminants. However, blasting does create a more adhesive surface for the powder coating after the part has been cleaned of residual soils.

Washing. Pressure washing, dipping, or automatic washing (with a soap specifically formulated for the soils specific to your fabricating process) are the most effective ways of cleaning the metal prior to the next finishing stage. Steam cleaning or hot water helps break down the oils and can reach difficult spots or gaps in the surface. Detergent is the best way of cleaning metal of oils, waxes, polishing compounds, or other substances that will prevent the powder from sticking to the metal.

Wiping. Solvent wiping is another way to clean up the metal of surface oils and contaminants, but it is an inaccurate way to clean. Since the part is manually wiped with rags, the rags can become saturated with the oil you are trying to remove.

Pretreatment For Better Powder Coating Results

Clean metal by itself can be immediately powder coated but that will not give you superior performance and weathering characteristics. A good pretreatment allows the powder coating to better bond physically to the metal, withstand exterior weathering, and prevents flash rust prior to powder coating.  Because of all the benefits associated with it, you should always consider adding metal pretreatment to your coating process.

There are a few of methods of pretreatment. The first one is chemically etching the metal with an acid based product that promotes adhesion of the powder coating to slick or difficult to adhere to metals. Aluminum is typically a very slick substrate, so it needs some sort of surface treatment to remove oxidation and to etch the surface. Etching chemicals are usually more difficult to work with than the next method.

The second method of pretreatment, phosphating, is used to improve the corrosion resistance of the product.  Iron phosphate is the oldest method of pretreatment. It is a great way to improve the adhesion of the powder as well as doubling or tripling the corrosion resistance of powder by itself. In a pure steel fabrication process, it is the most common chemical pretreatment. Zinc Phosphate is a more robust process that results in the best corrosion resistance for steel products that are meant for ships or near coastal areas.

Here are a couple of links to some data pages for iron phosphate and zinc phosphate products:

Iron Phosphate: http://www.ppgtruefinish.com/getattachment/3448357e-3e53-4cf9-bf96-a70b51160dd7/CHEMFOS-146FD.pdf.aspx

Zinc Phosphate: http://www.williams-oakey.co.uk/gardobondz3480.pdf

Besides etching and phosphating, a third method of pretreatment is Zirconium Non-Phosphate pretreatment. In essence, it is a combination etching chemical such as zirconium fluoride in a low solids acrylic sealer that bonds to the metal. This newer process is used for multi-metal operations and also combines well with cleaners for a 1-3 step spray system, depending on the chemical manufacturer.

Here is a more technical description of Zirconium: http://www.duboischemicals.com/pretreatment/links/zirconization.pdf

Meeting Your Customer’s Powder Coating Specifications

Finally, your customer’s specifications will determine the cost and complexity of your pretreatment process. If a tractor-trailer wheel needs to last 5-10 years on the road under heavy use in ice and snow, then the powder coater needs a superior pretreatment process. A decorative base for an interior table would not need the corrosion resistance as the wheel, but might need a good etch or blast profile to prevent powder loss due to being bumped from time to time. An interior fluorescent light fixture would need neither improved adhesion or corrosion resistance, but would still need clean metal for the powder to be applied defect-free.

With all these questions answered, you’ll be able to implement a pretreatment process that produces quality and consistent results for you and your customers.