Archives

Proper Grounding Techniques for Powder Coating

Powder Coated Parts After CuringOne of the keys to successful powder coating application is proper grounding. A good ground acts like glue to the powder being sprayed on the part, making it easy to get a uniform, high-quality finish with high transfer efficiency. A weak ground can cause a host of issues, such as light coverage areas, Faraday cage problems, larger hook marks, generally uneven powder application, dirtier spray booth filters, and poor transfer efficiency. In extreme cases, improper grounding can cause the operator to get shocked.

How to Get Proper Grounding for Your Powder Coating Gun

There are four main areas where your grounding technique needs to be addressed:

Grounding Rod. We have mentioned in previous articles that the best starting ground for manual spray applications is a 6’ to 10’ copper grounding rod installed just outside of the powder spray enclosure. Permanently attach a ground strap of at least a 14-gauge wire with a good clamp on the end that will be used to ground parts. When the ground rod is in rather sandy or dry soil, a small amount of water can be poured into the grounding rod hole and allowed to soak in prior to powder coating.

Clamp And Copper Grounding Rod For Powder Coating

For the best ground, make sure your clamp (left) is attached to a copper grounding rod outside the spray booth (right).

When using this grounding method, the powder will stick to the part like glue. The powder will resist being shaken off when moved or when encountering mild air movement.

IMPORTANT: Using just the grounding clamp supplied with the gun unit is inferior to using a grounding rod, but it’s better than nothing until you get your grounding rod installed.

Parts Rack or Cart. You will need good metal-to-metal contact from the grounding rod clamp to the part. If you clamp the cart in the same place each time, be sure to blow or wipe off the powder around the clamp attachment area each time BEFORE the cart enters the curing oven. This will prevent you from having to grind off this area every time you use the cart.

Custom Parts Racks For Powder Coating

When parts are attached directly to the rack or cart frame, metal-to-metal contact is usually achieved by the part shielding the rack’s contact points. It’s important to note that if you do not hang parts on every contact point, powder will accumulate on the exposed points and will have to be removed before using the rack again. Some operators use high temp tape or other masking agents to protect areas of the rack from powder that can become baked over the exposed metal.

If you use racks that have movable hooks to attach the parts using a bar or similar contact points, you need to grind the tops of the bars every 5-6 coating cycles. This will ensure a good ground and proper transfer efficiency. If you hear popping sounds while applying the powder or see small instances of electrical arcing from hook to rack, flag that rack to be cleaned via grinding or stripping before using it in the next coating cycle.

Racks can usually be manufactured by any local metal fabrication shop. Many job shops make their own. When designing racks or carts, remember to concentrate parts so they are two feet from the floor to about six feet high. This will allow the operators to spray all areas fairly easily.

HParts Being Powder Coated On Hooksooks. As with the cart, you need good metal-to-metal contact with the cart and the parts. Most shops can get 5-6 uses from a hook before it starts becoming insulated by baked-on powder. Some powder coaters just replace the hooks with new ones, but others have them cleaned. Cost analysis will tell you which is more efficient. If you are getting arcing and the rack has been cleaned, then you need to clean or replace your hooks. Mighty Hook is a great source for hooks, plugs, and tape. http://www.mightyhook.com/default.aspx

Parts. Not all parts ground well. Because of their mass, some parts can be tough to ground properly. Also, if parts have been coated before, they can be more challenging to ground. Sometimes the racks don’t ground parts adequately because the parts hang too far from the grounding point. In these cases, you can clamp directly to the part in question. After spraying the powder, just remove the clamp and spray the clamped section last to keep from getting surface defects.

If you’re worried that you might not be getting a good ground, use a megohmmeter (often called a “megger” after the company that makes these types of test instruments: http://us.megger.com/) to check the resistance from area to area. If the resistance exceeds 1 megohm from ground to part, work backwards at all the contact points to determine where the loss of ground is occurring.

Using professional quality powder coating equipment can solve many of your coating issues. All of Reliant Finishing Systems’ equipment is designed to provide the best finishes possible for today’s powder coating operations. Find out more about Reliant equipment here, or give one of our systems specialists a call today.

Tips For Touching-Up A Powder Coated Finish

Pump Casting With Powder Coated FinishOne of the many advantages powder coating has over wet paint is the variety of ways you can fine-tune and rework a powder coated finish. This article discusses some of the different touch-up techniques you can use to clean up your work and get the best overall quality for your powder coating projects.

Why Should You Touch-Up Your Powder Coated Finish

Visual Appeal. This is the obvious reason for fixing a powder coated finish. To most customers, if it doesn’t look right, it isn’t acceptable.

Performance. Some powder coatings are purely functional, so they don’t need to be aesthetically perfect. Usually there are one or more standards (such as corrosion resistance) that have to be met. A defect can compromise the finish integrity and cause a part to fail to meet a specific customer’s standards.

Warranty. If the powder coated part has any sort of warranty, then special care should be made to make sure the part passes end-of-the line QC testing. A part may look great and have no apparent defects, but if it does not pass the customer’s minimum testing standards, a repair or rework is needed.

When Is The Right Time To Do Touch-Up Work?

The best time to catch your coating mistakes is prior to curing the powder. The powder can easily be blown off with compressed air or wiped off and then reapplied with very little hassle. Get in the habit of checking your parts for application errors before you start the curing process. Every mistake you catch here will save you time, effort and money later.

Common Powder Coating Touch-up Techniques After Curing

It’s not always possible to catch coating errors, especially if there are overbaking or underbaking issues with your oven. When dealing with a defective finish, you should ask yourself: will a touched-up surface be acceptable -both visually and from a performance standpoint-or should you repaint? In either case, if you have to resolve a finish problem, here are some of the most effective techniques to use once a powder coated part has been cured using Reliant’s products:

Liquid Paint Touch-Up

Many manufacturers use color-matched liquid enamels to cover hook marks, missed areas, Faraday areas, re-welds, sanded spots, handling damage and other defects.

Pros – cheap, fast, least labor intensive, little skill required

Cons – not visually appealing on a class A part, visual “halo” around repair, repair is not as durable as the rest of finish, repair may fade or chalk faster than surrounding powder coated finish

Usable with most decorative finishes. This repair method is fine except for on the primary surface a customer can see.

Re-coating

In some instances, your powder process can allow for a repainted finish to go over a previously painted part with no prep work. Usually the part must be freshly powder coated with no contamination on the surface.

Some chemistry is not compatible with this method and the surface will need to be abraded (blasted with abrasive grit or scuffed with sandpaper) and then wiped down with alcohol. If the part has been cured for more than a week, it will almost always need to be abraded and cleaned before re-coating. 

Pros – Less expensive and faster than stripping, better corrosion protection than liquid enamel

Cons – Adhesion risk (always do a test part and check adhesion), too much film build-up could cause issues (weight, measurement tolerances, extreme temperature checking)

Many small parts manufacturers will re-run parts after inspection if they have light powder coverage or other easily repaired surface defects. In the closet hardware and racking industries it is especially common for facilities to repaint parts once or twice if they are having an acceptable amount of rejects.

Tip: Remember to use your powder gun’s re-coat settings to properly apply a second coat

Sanding And Buffing

Sanding and buffing the powder finish can eliminate surface trash and some defects. This also helps smooth out orange peel that naturally occurs with most powder coatings on parts where the powder thickness is excessive in a particular area. Sanding companies like 3M have a series of abrasive and buffing compounds that allow shops to sand out defects and then bring the surface back to a smooth shine.

Pro’s – Mirror-like finish, faster to buff than to repaint

Con’s – Burn-throughs will need to be repainted or touched up with a liquid paint, labor-intensive, requires moderate skill

In the automotive and other transportation industries, manufacturers will sometimes sand and buff out Class A type parts such as hoods or panels that need to have a mirror-like defect free finish. This is similar to work done with wet paint. It takes some experimentation to develop a successful sanding and buffing process.

Tip: The sooner you buff after curing, the easier it is to work with the finish. Power coating gets very hard 1-3 days after curing.

IMPORTANT! Be sure to have the buffing operation isolated from the finishing operation. Many of the waxes and compounds used for buffing and polishing do not react well with painting and powder coating processes and can cause defects like “fish-eyes.”

 Fillers And Putties

There are many products like Bondo and Lab-metal that can be used to fill gaps and seal holes prior to powder coating. Before adding a filler to your process, make sure it is compatible with 400° to 450° F curing temperatures and that it is recommended for powder coating.

Pros – Eliminates re-welding for small areas, surface defects are much less noticeable if repaired prior to powder coating, parts do not need to be taken off-line for repair

Cons – Powder may have trouble being electrostatically attracted to the repair, in a large area adhesion can be suspect, may cause powder finish to “shimmer” or look different over repair

Trailer companies often use filler-putty to bridge gaps in their dump-style trailers. Tiger Drylac has a two-component filler that has some conductive elements for good results when used under a powder coated finish. Here is a link to their data sheet:

http://www.tiger-coatings.us/fileadmin/user_upload/downloads_us_new/product-data-sheets/tiger-drylac/special-products/Epo_Strong_Series_93-70080_Epoxy_Repair_Kit.pdf

Total Strip And Repaint

If there is a catastrophic finish failure, starting over after taking the finish off down to the bare metal can sometimes be the only solution. Major powder coating issues, like severe adhesion problems in high-performance parts, often require a total repaint. Pretreatment failures, parts contamination after pretreatment, underbaking, and overbaking can also cause problems that are so bad that the only answer is to totally strip the coating off and redo the process (after you have identified and corrected the fault in the process). Remember, the finish is only as strong as its weakest layer, so if you notice flaking once the finish is cured, it will need to be completely redone.

Pros – Once the process is fixed, you have high quality parts going to the customer and you don’t have to worry about field failures and the possibility of costly claims in the future

Cons – Costliest and most time-consuming solution

For demanding projects like government contracts, high-performance industrial components, engine parts, military equipment, parts that will be exposed to a highly corrosive environment or impact/abrasion in the field, the only way to insure quality compliance for parts that have badly defective finishes is to re-work the parts down to the metal.

The Nail Polish Fix

We’ve just outlined the most common touch-up and re-work methods, but there is another technique that can sometimes get positive results. An uncommon method for fixing small finish imperfections is to put a small amount of the powder in a clear lacquer and use it as touch-up paint. It’s possible to use hair spray, nail polish and other lacquers in a hobby situation, but bulk materials will be needed in a professional environment. Although the touched-up area will visually match the cured powder paint, the repaired area will not have the same durability as the cured surface. Remember, if you need the same surface integrity and durability in your touch-up areas as you do with the powder coated finish, you will probably need to use a two-component catalyzed topcoat and possibly a zinc-rich epoxy primer for appropriate corrosion resistance.

Meet Expectations With The Right Powder Coated Finish

To retain business and keep customers happy, you need to know exactly what each customer expects from the powder coated finish you are providing. Once you know that, you can develop a process that includes a repeatable touch-up system that addresses defective finishes of all types. Proper touch-up and re-work techniques help ensure great finished products.

Using professional quality equipment can solve many of your coating issues, including overbake and underbake problems associated with outdated or inferior quality ovens. All of Reliant Finishing Systems’ equipment is designed to provide the best finishes possible for today’s powder coating operations. Find out more about Reliant equipment here, or give one of our systems specialists a call today.

Understanding Powder Coating Gun Settings

When you first start powder coating, adjusting your powder coating gun settings can be confusing. We’ll cover the most important terms and settings for everyday powder coating situations and addresses some common issues you may encounter. Once you understand how electrostatic powder guns work and know what the basic gun settings do, you can improve your powder coating results quickly and confidently.

Author’s Note: All examples in this article use the Wagner EPG controller for illustrative purposes, but other brand-name professional quality guns have similar controls.

Powder Coating Gun Settings # 1: Kilovoltage (kV)

Powder Coating Gun kV Meter“kV” is the symbol for kilovolt. One kilovolt = 1000 volts. It is a unit of measure indicating how much electrical charge an electrostatic powder gun can produce.

The kV adjustment changes the amount of voltage charging the powder particles as they pass through the gun. The higher the setting, the stronger the charge. High settings are great for flat panels and the outside of box-like parts. A high kV setting can improve your transfer efficiency (more powder sticks to the part) and also allow you to increase the distance between the gun and the part. This can help you get very uniform coverage on flat surfaces. In some cases, excessively high kV settings can cause tiny pits or dimples in the finish due to “back-ionization.”

Lower kV settings are best for Faraday cage areas and when working with some specialty powders, such as metallics. As a general rule, the more detailed and complex the part, the lower the kV setting. Professional quality powder guns from companies like Gema, Nordson and Wagner typically have a maximum voltage setting of 100 kV. A good starting point is a setting of 50 to 80 kV for applying a single coat (or the first coat) to an uncoated part. When working with Faraday cage areas, turn down the voltage. When applying a second coat, a lower kV setting can give the best results.

What is the Faraday Cage effect? This describes what happens when you are trying to powder coat into a recessed area like the inside of a box. Highly charged powder particles are attracted to the closest grounded metal surface–the sides of the box–so they have a difficult time penetrating into the corner. This often happens with parts that have tight corners, angled features, prominent bends or recessed areas. Window and door trim, frames, boxes, wire racks, I-beam sections, angle iron, conical parts, u-shaped channels, uni-strut, grids, and other unusually shaped parts can be tough to coat without adjusting the gun’s output. By reducing the electrical charge (lowering the kV setting), you can help sprayed powder penetrate Faraday cage areas more effectively.

It is important to have a good ground. This is the physical connection that allows an electrical current to follow a path to earth. A ground is needed for the charged powder particles to effectively be drawn to the metal part. The stronger the ground, the more effectively the electrostatic process works. We recommend the use of a dedicated grounding rod. Get a copper grounding rod of at least 8’ length from an electrical supply company. Drive the grounding rod into a spot as close to your powder spray booth as possible (yes, you will have to penetrate your concrete floor if you have one). Using a good quality grounding strap of 14 gauge or heavier wire (heavier is better) and a well-made clamp, connect the ground rod to the rack or hook that is supporting your part. This will dramatically improve the performance of your coating gun, especially when dealing with complex parts. In some areas, you may need to pour a few ounces of water into the hole around the grounding rod to improve the quality of your ground.

Another way to improve results in Faraday cage areas is to aim the gun near the corner or detail area, but not directly at it. Wrap is the term that describes when sprayed powder is attracted to the back side of the part. Wrap means that the gun delivers powder to areas of the part that aren’t directly in front of the gun’s output. By having a good quality ground, you can get improved wrap on panel-shaped parts and improved penetration into Faraday cage areas.

Remember, voltage and amperage are not the same thing, so it may be important to also adjust the amperage at which the powder is being sprayed.

Powder Coating Gun Settings #2: Microamperage (µA)

Powder Coating Gun Microamperage Meter“µA” is the symbol for microampere. One microampere = 1/1,000,000th of an ampere. It is a measurement of electrical current. It indicates how much charge is moving from the gun’s electrode to the cloud of air and powder exiting the gun, and then onto the surface of the part being coated. This may be the hardest gun feature to understand.

Voltage and current (measured in microamperes) have an inverse relationship when you’re talking about powder coating guns. Voltage is a measurement of electrical “potential to do work,” while current is a measurement of the actual movement of electricity–“the work being done.” When some of the potential energy is used, it becomes current. As current increased, there is less potential (unused energy) left. A gun’s current feedback system can indicate to the operator what the electrostatic charge is doing. It is, in some ways, more useful than just looking at the kV setting. This is because the microamperage reading tells you how much of the charge is working, instead of just indicating the charge’s maximum potential like the kV setting does. On powder guns like the one shown from Wagner, you can see the effectiveness of the charge and limit how much current is possible. This allows you to understand and control how much energy is being used.

The kV setting is, in part, restricted by the power supply. While spraying a part, the load on the power supply limits the actual output, so the voltage may be lower than the setting. The current load increases as the gun gets closer to the part being sprayed. On a gun with an adjustable current limiter, when the current load reaches the set limit, the kV will quickly decrease. This helps prevent problems from too much voltage (like dimples in the coating from back-ionization), especially when the gun is too close to the part. Also, if the amperage is not limited to a certain range, the transfer efficiency may suffer in Faraday cage areas or the powder may not coat evenly if the gun-to-part distance is inconsistent. Setting the µA range to 20-25 can help with difficult to coat areas.

Powder Coating Gun Settings #3: Air-Flow/Powder Volume Dial

Powder Coating Gun Air-Flow DialWagner powder application guns automatically balance the powder output with the airflow via the main dial. The number selected is the actual maximum percentage of powder that can be used. Typically, 70% is the highest you would want to go. When working with intricate parts, this number can be much lower.

 

 

Powder Coating Gun Settings #4: The Factory Presets

Powder Coating Gun Factory PresetsThese are settings pre-determined by the gun manufacturer or the operator. They are intended for the most common scenarios encountered by typical gun users.

Flat Panel Setting: This setting provides maximum kVs and a high volume of powder being sprayed. This is for large flat panels and will provide a lot of powder wrap.

Repaint Setting: This setting is for a previously painted part that needs more powder for cosmetic or performance reasons. The kVs are reduced, as is the powder volume, since there is already powder on the part.

Faraday Cage Setting: This setting lowers the kVs, restricts current µAs, and reduces the powder flow percentage to allow powder to penetrate difficult-to-reach corners and angles.

Custom Settings: These are the settings that you use with a specific powder or part. The fourth preset is reserved for custom settings. (On the Wagner controller, you have up to 50 available custom settings that can be saved.)

My Powder Coating Gun Is Set, Now What?

Once you’ve got your powder gun adjusted correctly, you are ready to start spraying powder. Before you begin coating a part, look at the part and figure out how you will get the best and most efficient coverage while spraying. As your part becomes coated with powder, a charge will build up on the surface. It will make the Faraday areas even more challenging to coat. Therefore, it is best to coat the Faraday areas first, then spray the flat surfaces of the part.

After rehearsing what you are going to do, you need to get the powder flowing smoothly through your gun. Spray the powder coating gun away from the part until a uniform cloud is coming out with no sputtering or surging. This may take up to a second or two. Move the gun to the part and move it in a slow, controlled motion across the part, keeping a gun-to-part distance of around 8”. Keep the gun triggered and spraying until the part is done—don’t start and stop. If possible, try to get full coverage with a single pass across the entire part. Often you will need to move the gun in a controlled back-and-forth motion, starting with side-to-side movements and then switching to up-and-down passes if needed.

Inspect the coated part with a bright light to help detect thin spots. Touch up any spots you see before curing the part, but be careful not to add too much powder or to let the gun puff powder onto the touch-up areas. These common mistakes happen when you become impatient and blast the part with a heavy fog of powder or don’t let the gun’s powder flow stabilize before attempting touch-up work.

What Else Do I Need To Know?

Air Supply Problems are not uncommon. It is critical that you use only cool, dry, oil-free compressed air to power your powder application guns. Make sure you have an accurate in-line pressure gauge and a regulator that can restrict the amount of pressure reaching your gun. You may need to use a powered air dryer, and you will definitely need a filter system that traps moisture and oil.

Fluidization is what we call the small amount of air movement that aerates and fluffs the powder around the pick-up tube on a box-feed unit. An adjustable valve controls how much air is provided. The air helps break up clumps of powder before they are pulled into the pick-up tube and pumped through the gun. It is also the term used for the air movement that mixes the powder in a hopper container. In the hopper unit, there is a plastic membrane at the bottom with lots of tiny holes that allow the air to condition the powder. When adjusted correctly, it will look like the powder is slowly boiling.

Impact Fusion describes what happens when partially gelled powder sticks to sharp areas in the gun and inside the powder pump. This problem is more prominent in hot shop environments and when working with poorly conditioned powder. The stuck-on powder can be removed with a clean, fresh shop towel and denatured alcohol.

Mil Thickness is the term used when talking about the thickness of the powder coating material that has been cured over the surface of a part. One mil = 1/1,000th of an inch. A healthy human hair is about one mil thick. Most powder coated finishes are between 2 and 4 mils thick, with some finishes up to 6 mils or thicker. Achieving ideal powder thickness and uniform coverage takes practice. Make sure to keep good notes. Some coating instructors have their students spray test parts to learn about adequate powder coverage. A student sprays a part while the instructor illuminates the surface of the part with a bright pocket flashlight. Once the flashlight no longer reveals any bare metal spots, the student stops spraying. This method typically results in a finished coating that is about 2 mils thick.

Orange Peel describes the uneven, “wrinkled” finish that can happen after curing if the painter sprays too much powder on the part in some places. You can end up with areas of heavily concentrated powder that flow out into wavy sections that have something of an orange peel texture. The excessively thick powder in these areas will also make the finish more prone to chipping. If the applied powder is under-cured, especially as the result of the oven temperature being too low, the powder can also fail to flow out properly, even if it’s not too thick, causing the same type of textured defect in the finish.

Powder “Starved” Finish/Light Powder are terms used to describe the grainy texture that a defective finish can have after it is cured if the part does not get adequate powder coverage. If there wasn’t enough powder on the part for it to flow together and create a uniform coating, it can have an odd, textured appearance. Even worse, the part will likely start to rust or oxidize in these textured areas because the part’s surface isn’t fully covered by the coating material. Using a powerful flashlight or LED inspection tool can help prevent this by allowing the painter to see areas that need more powder.

A professional powder coating gun can make a huge positive impact on your operation, allowing you to coat with more accuracy, better efficiency and higher quality. Reliant Finishing Systems only offers professional powder guns from companies like Wagner. Need a new powder application gun or a complete powder coating system? Our powder coating specialists are ready to help – give us a call today!

The Basics Of Powder Coating Coverage

Powder Coating Gun And PartKnowing how much powder you need for a particular job is critical when determining cost. Without that information, it is easy to make pricing mistakes that can drain your profits or run off potential clients due to pricing that isn’t competitive.

However, calculating powder cost can be a little confusing. We’re going to show you how to calculate powder coating coverage and how to gather the information necessary to give an accurate prediction of cost per square foot.

 

The Data You Need To Calculate Powder Coating Coverage

Before you start calculating coverage costs, these are the values that you will need to know :

  • Powder Specific Gravity
  • Cost Per Pound of Powder
  • Transfer Efficiency
  • Dry Film Thickness
  • Square Footage of Metal To Be Coated (Per Part)

Powder Specific Gravity: This is usually supplied by the powder coating manufacturer on their technical data sheet. Remember that not all powders of the same color have the same specific gravity.

Cost Per Pound of Powder: Check your invoice or get the cost from your powder manufacturer or sales representative.

Transfer Efficiency: Transfer efficiency is the percentage of the powder that is being applied to the part instead of being wasted as overspray. Transfer efficiency is almost always an estimated figure and the most difficult one to determine when estimating coverage costs. It is hard to get an accurate percentage of how much powder is being applied to the part and how much is going in the filters, on the floor, on the rack, and getting stuck to the booth’s walls.

Powder Coating Gun Overspray

Transfer efficiency is directly impacted by how much powder the operator is using.

Transfer efficiency is directly related to the way the operator is applying the powder. If there is a giant cloud of powder in the booth or a heavy fog of powder blasting out of the gun, you can bet that there is more wasted powder than if the operator is spraying lightly enough to coat the face of the part and still get a gentle wrap of powder moving around the part to partially coat the other side.

Proper ground and powder coating gun quality can have a significant effect on transfer efficiency. A shop with a dedicated ground rod that is connected to the parts rack or hooks, or to an uncoated portion of the parts, can always get better transfer than one that doesn’t. Likewise, a shop using a professional quality electrostatic gun with adjustments for powder flow, voltage and current can get better results than one using a hobby gun.

For estimation purposes, if this is a new operation with untrained painters, the transfer efficiency can be as low as 25%-30%. After proper instruction, experience, gun adjustment, and proper ground, the transfer efficiency can reach 70%. If you are reclaiming the powder by collecting and reusing the powder, you could possibly reach 85%.

One way to calculate transfer efficiency percentage is to determine how much powder is applied to a part in the time necessary to fully coat that part. You will need a high quality digital scale and a timer to do this. First, weigh your part before you spray it. Get your timer ready and spray the part until it is fully coated and ready to cure. Record the time it took to coat. Now, weigh the part again to learn how much powder was deposited. Next, turn off the gun electrostatics but do not adjust the powder flow or air and spray the powder gun into a porous filter bag that will trap the powder but allow the air to flow through (you can get these online or from your powder supplier). Spray powder for the same length of time it took to spray the part. Weigh the bag before and after to measure how much powder was applied. Then apply the following formula:

Powder Deposited (the weight of the powder on the part) divided by Powder Applied (the weight of the powder in the bag) multiplied by 100 will give you the basic transfer efficiency percentage.

Powder Coating Gun Applying PowderDry Film Thickness: This is the amount of powder you would like to apply to the part, measured in terms of coating thickness. You can measure a part with a DFT gauge to get an average of the mil thickness across a section of the part’s surface. You should take as many readings as possible, then average them, to get the most accurate estimate of the overall average thickness.

Square Footage of Metal in Your Part: This might take a bit of calculation but it will give you the cost per part at the end of this exercise.

Powder Coating Coverage Formula

Now that you have all the data you need, you can apply the powder coating coverage formula.

Assumption: The Powder Coating Industry standard is 192.3 square feet of coverage per pound of powder. This pound of powder would be at 1.0 specific gravity and applied at a thickness of 1 mil with 100% transfer efficiency. In other words, this is how much surface a common powder could cover if no powder was wasted and you only needed a thickness of 1/1000th of an inch.

So the formula would be:

Actual Coverage Rate (ACR) = 192.3/Specific Gravity/Mils x Transfer Efficiency (as a decimal)

Example: Powder A has a 1.5 specific gravity and is being sprayed at 2 mils with 50% transfer efficiency. The powder cost is $5.00 per pound. The part being sprayed has 3 square feet of surface area.

ACR = 192.3/1.5 (specific gravity)/2 (mil thickness) x .50 (transfer efficiency)

ACR = 32.05 square feet per pound of Powder A

Next, take your cost per pound and divide it by your ACR.

Cost per square foot = $5.00 (cost of one pound of powder)/32.05(ACR) = cost is $0.16 per square foot of coverage by Powder A

Multiply this cost by the square footage of your part’s surface area and you’ll know the cost of the applied powder.

Cost Per Part = 3 (square feet of part) x $0.16 (cost per square foot) = $0.48 per part in powder cost

Now that you know how to do this by hand, Interpon has a nice online calculator that you can use here: http://www.interpon.us/our-coatings/powder-coverage-calculator/

Knowing what your cost is for powder coverage will prevent you from making costly budgeting mistakes and keep your prices competitive.

Powder Coating Gun For All ApplicationsIn order to maximize your profits you have to maximize your transfer efficiency, and the best transfer efficiency comes from professional powder coating guns. Professional guns provide multiple settings and factory-presets to get the right amount of powder onto your parts without excessive waste. Reliant Finishing Systems only provides professional quality powder application guns from industry-leading companies like Wagner. When you buy from Reliant, you know you’ll be getting the gun you need to get the job done right.

Looking for a new powder coating gun or new powder coating system? Give us a call today – our systems specialists are standing by to answer your questions and help improve your operation.

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.