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Innovative Powder Coating Oven Airflow Leads To Improved Performance

Powder Coating ovens from Reliant Finishing SystemsAt Reliant Finishing Systems, we pride ourselves on providing some of the most energy efficient powder coating ovens in the world. Our ovens reach curing temperatures much faster than many of our competitors’ ovens and at a fraction of the operating cost. If you need a powder coating oven that can provide professional quality results on a daily basis, a U.S.-built oven from Reliant Finishing Systems will get the job done, and it all starts with the powder coating oven airflow.

It Starts With The Airflow

Reliant’s innovative design uses one or more powerful direct-fired burners to heat the oven through an overhead plenum. Hot air is injected from the plenum directly through the oven’s ceiling. Each heat unit continually pulls the coldest air from the bottom of the oven back through the burner to be reheated. At the same time, the exhaust is constantly pulling cold air from the floor and enabling hotter air to move into every corner of the oven’s interior. This combination of vertically positioned heat units and floor-mounted exhausts is unique—and just plain better.

Reliant Powder Coating Oven Airflow

Typical airflow of a Reliant powder coating oven with a side-mount exhauster and rear-mounted burner and heating unit.

By comparison, many other ovens on the market use both roof-mounted heaters and roof-mounted exhaust units. We don’t use this design because it makes routine maintenance tasks and inspection much more difficult – the operator has to climb on top of the unit every time anything needs to be checked. Also, top-mounted heat units and exhaust units remove the hottest air from the oven instead of the coldest. Why would our competitors build ovens this way? The answer is that this design is much cheaper to build.

With a Reliant powder coating oven, since we’re taking the coldest air from the bottom of the oven in a constant cycle, the oven air is much more evenly heated throughout the cabin. This has two major benefits. First, the oven quickly reaches a very stable temperature. Second, that constant temperature means you won’t have to deal with hot and cold spots in your oven. By eliminating temperature inconsistencies, the powder can cure evenly and uniformly without the potential for flaking, undercuring, or overbaking. That means a better and longer-lasting finish.

But what does that mean for you? Because our ovens get to temperature quickly and sustain that temperature evenly, they require far less fuel to operate. Typically, our customers using standard models can get their ovens to 400 degrees or more within 10-15 minutes, and maintain that temperature for an entire production day with minimal energy costs. For one of our most popular models, an 8’ x 8’ x 20’ walk-in oven, heating costs are often as low as $3 per hour on average.

Get The Most Efficient Powder Coating Oven From Reliant

Reliant’s superior airflow design is just one of the reasons why we’re so proud of our powder coating ovens. A Reliant powder coating oven is built to give you reliability, fuel economy and top-notch performance at an unbeatable price. Don’t just take our word for it, ask for references so you can talk with our customers about the incredible results they are getting every day with Reliant equipment. Click here for more information on our powder coating ovens and related powder coating equipment, or give us a call today.

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.

What Finish Do You Need?

We’ve already talked about the benefits of powder coating over traditional wet paint and how setting up your own system can save you considerable time and increase your ROI. But what do you need to do now that you’ve decided to start your powder coating operation? Understanding what you are going to coat and what your powder specifications are will help you make the right decisions.

Determine What Type Of Powder Coating Finish Your Customers Want

When you start your powder coating operation, you need to know what performance specifications your customers require. This can be as easy as matching the performance of your current liquid operation or using the same powder as your current outsourced job shop. However, if you are in a highly technical industry – like supplying car or tractor parts – then there could be specification on salt-spray resistance, color retention, gloss loss, adhesion, flexibility, or hardness.

Here’s an example: If you powder coat parts for a larger manufacturer, that manufacturer may already powder coat and assemble some of their larger parts in-house. If you are, for example, supplying powder coated parts to John Deere, you will be using the same powder they use for their products. There might be no way to match their pretreat process, but you will need their powder specifications to make sure your parts integrate smoothly with their operation.

The Powder Specification Indicates What Equipment You’ll Need

The powder specification will provide you with a lot of important information, including powder thickness and cure times. This will tell you what type of oven (https://www.reliantfinishingsystems.com/powder-coating-equipment/powder-coating-ovens/) you will need as well as how much powder you have to apply. Is the thickness excessive? If yes you might need to pre-heat the part to get more powder to stick. The specifications should also say what type of pretreat process is required before coating. Iron Phosphate or Zinc Phosphate might be designated. Zirconium is also a common pretreat chemical that is used for multi-metal pretreating.

These specifications will dictate what type of pretreatment process you will need as well as what type of finish process your products will require. Once you have decided that, then you need to figure out how many you want to coat a day.

Choosing The Right Equipment For The Job

Your finish process is very dependent on the type of powder the finish specifications require and your coating equipment must be able to handle the workload in a quick and efficient manner.

For example, if you have to use a super-durable polyester baked at 385-400 F for 10-15 minutes, then you need an oven that is large enough and has enough power to cure the powder in an even and timely process. But if you are coating low cure epoxies, they only needs 8-10 minutes at 325 F for full cure. You wouldn’t need as powerful an oven to cure the epoxies as you would with the super-durable polyester.

If you plan on doing both, then engineer your equipment to the higher end. I always ask manufacturers to look five years down the road for their projected production requirements and possible finish improvements they would like to see.

Asking the Right Questions Before You Get Started

Ask your powder supplier for the curing and application specifics. This will help you decide on the basic system you would like to implement. Not all powders are the same though many are similar. Remember cure time is part temperature at cure time. The heating up of the metal does not technically count as cure time.

Your Process Decides Basic Equipment Selection

Once you know your proposed finish process, you can easily decide which equipment is right for you and your customers. Finishing can be broken down into three basic elements which help inform you on what sort of equipment you’ll be installing:

Metal Preparation – sand-blast, cleaning, solvent wiping, pretreating, and/or drying

Application – hand-spray, multiple coats, automatic spray, and/or possible priming

Curing – batch oven, conveyor oven, and/or IR oven

We have a lot to talk about in future articles, including pretreatment selection, powder chemistry and equipment selection, but suffice to say, having the finishing details first helps with the more expensive equipment decisions later.

Need help? Please give one of our systems specialists a call today, or check out our Resources page for more educational information on coating equipment, powder coating and more.

 

Bringing Your Powder Coating In-House

We’ve already covered many of the advantages powder coating has over liquid paint: how it can cost you significantly less and is more durable all while being a cleaner and safer process. This time we will discuss when manufacturers are outsourcing their finishing to a job shop and are deciding whether or not to bring their powder coating in-house.

Yellow Powder Coated Rims

Adding a powder coating line can help increase quality and reduce cost. (Photo courtesy of Espo’s Powder Coating in New York. Reliant equipment shown).

Getting Control Over The Finish

Every manufacturer I’ve worked with told me that improved quality was the number one reason for bringing their finishing in-house. This isn’t to say all job shops have poor quality, but they may not have the tight specifications that the manufacturer would like. Irregular thickness, adhesion problems, surface defects, gloss, color mismatch, and damage are all characteristics of outsourced coatings, and all of them create costly delays. For many manufacturers, adding an in-house line was easily worth the investment to control the defects from their outsourced partners .

The Costs of Outsourcing vs Coating In-House

As an example of typical powder coating costs, I looked at a large chain automotive parts retailer. To buy an uncoated wheel rim it costs roughly $50. For this same wheel rim, it costs $100 for a single color powder coat. For an exotic two-coat color (such as Hyper Silver) the wheel rim can reach $450. Granted the last wheel is far more stylized and the finish must be perfect, but the mark-up involved can be substantial.

Outsourced Cost: 4 Rims x $50.00 = $200.00 + Freight

In the above example, if brought in-house, the materials cost for doing a set of 4 wheel rims would be about 1 pound of powder. Say $7.50 a pound for a normal color. Pretreatment chemicals would cost about $0.50 per gallon of water. You would use approximately 2.5 gallons of water to clean 4 wheel rims, so $1.25 for chemicals. Well-insulated ovens have a gas/power cost of about $5-8 an hour, so let’s say $6.50 an hour. It only takes ½ an hour to cure the 4 rims, so energy cost of $3.25. Labor would be approximately $20 an hour and you could cycle 4 rims every 30 minutes, so $10 labor in 4 rims cost.

In-house Cost: $7.50 (1 lb of powder) + $1.25 (pretreatment chemicals) + $3.25 (Oven operating cost) + $10 (1/2 hour labor) =  $22.00 for all / $5.50 per rim

The total part cost for finishing in-house would be $7.50(powder) + $1.25(pretreat) + $3.25(oven) + $10 (labor) = $22 for 4 rims or $5.50 cost per rim. This is a rough estimate and doesn’t include all costs but if the wheel manufacturer was having their wheels painted somewhere else, the $50 cost versus $5.50 cost is significant. This example also only factors for a small batch of 4 rims; with a larger coating production run, the in-house cost goes down even further.

Manufacturers know their cost of outsourcing by how much they pay per part. But there are other costs besides raw production to consider. Shipping the part back and forth, packaging the part, inventory costs of parts coated and waiting to be coated, delay of available parts costs, and damage to parts are all factors when comparing outsourced to in-house coating.

Flexibility and Rush Delivery Favor In-House Operations

Often times manufacturers need a small parts run fairly fast to avoid costly delays. Whether you’re replacing something that may have been fabricated wrong, or a slip up on a pick list that they didn’t have the correct inventory, being able to fix these issues prior to shipping is valuable. Having the powder coating in-house allows for quick turn-around for these and other unforeseen issues. As we’ve already discussed, since powder coated items can be finished, cured and packed quickly, having the ability to coat in-house can save days of delay.

 Having your coating in-house is also instrumental for the research and development of new colors or new fabricating designs that you would rather keep private. This finishing flexibility allows for the experimentation with new technologies and improved quality processes that can give companies a competitive advantage.

Deciding When an In-house System Is Right For You

When deciding whether to install a new powder coating system in your operation, the real challenge is comparing all your costs to see if the benefits are worth the investment, labor and learning curve of developing a good finish process. Training and flexibility are very important when starting a new finishing process, as is setting realistic goals or expectations (though we can certainly help you get up to speed with your new equipment). Remember to keep a good relationship with your job shop vendor, since you may need them in the interim and if your finishing capacity gets maxed out.

Ultimately, if you are only coating a few things a year and don’t anticipate adding powder coating to your process, outsourcing can be a very effective way to handle your coating needs. However, if you’re already outsourcing a sizable amount of work every month and are concerned about cost, quality or delivery deadlines – or all three – it’s time to consider bringing you powder coating in-house.

Looking for additional information to help your purchasing and powder coating operation? Please check our Resources page.

Advantages of Powder Coating Over Liquid Coating

In the previous article, I talked about pure cost per square foot savings and general material cost savings of powder coating over liquid coating. Today I’ll discuss some of the other advantage of powder coating that can save you significant time and money.

Curing Times Are Significantly Faster With Powder

Powder coating can help you get the results you want in a fraction of the time.

Powder coating can help you get the results you want in a fraction of the time.

The average catalyzed automotive or industrial liquid polyurethane is 2-4 hours cure to touch. The drying time can be accelerated by baking at around 235 F for 45 minutes, but that will only get the parts dry enough for limited handling. In most case, an extended cure time of about 1 hour is required before the parts can be assembled. Most liquid coated parts cannot be packed for shipment unless they have had an overnight dry time.

After the metal reaches a part temperature close to 400 F, powder coating cures on average in 10 minutes. Sometimes thick metal requires 30-45 minutes in the oven (and sometimes longer for especially dense objects). But after the part has cooled to handling temperature, it can be assembled and packed right away. Powder coating results in hours of saved process time and fewer parts in inventory waiting to be assembled or shipped.

Environmental Impact And Flammability Concerns Are Significantly Decreased With Powder

The average VOC (volatile organic content) of liquid coatings is between 3.5 to 5.5 pounds per gallon. This usually means about 1/3 to ½ of a gallon of paint goes into the atmosphere as emitted solvents. Many manufacturers have limits on how many tons (yes tons) of solvent they can put into the atmosphere. They have to pay for permits and will pay fines if they exceed their limit on these emissions. Powder has zero emitted solvents and no solvent flammability concerns. Using powder simplifies the permit process, reduces insurance risk, and generally provides a much more environmentally friendly process.

Processing Time And Number of Coats Are Greatly Reduced With Powder Coating

A regular polyester powder coating is comparable to a two component liquid polyurethane over an epoxy primer. Both systems need good clean metal that has had some kind of pretreatment to achieve maximum salt spray resistance. The liquid system then needs an additional primer to aid the topcoat in further durability and adhesion. Powder can eliminate the primer and be directly applied to the clean pretreated metal.

Powder also is 100% solids while liquid coatings average 50% solids. So if you have a paint thickness specification of 4 mils DFT(dry film thickness), then you can achieve this with one pass of powder. It will take 2-3 passes of the liquid coating, with some dry time in-between, to achieve the same thickness.

Powder Coating Is More Energy Efficient Than Liquid Coating

Powder coating equipment is generally much more energy efficient than equipment used for liquid paint. Because of safety concerns, liquid paint equipment uses more air and requires more air changes to filter out VOCs.

A liquid paint booth sized at 8’H x 10’W x 10’L uses approximately 16,000 cfm. A similarly sized powder spray booth uses approximately 8000 cfm, half what the liquid booth does. This means smaller fans and less shop air drawn through the booth when using powder. Liquid booths must also be exhausted to the outside to vent their emitted solvents. Since powder coating has no solvents, powder booths can be exhausted back into the shop by using HEPA filters on the final filter. The air is cleaner than the supply air that went into the booth.

If you are using a liquid coating oven to reduce your drying time, it will require more air exchanges than a powder coating oven. Since the powder oven can recycle its hot air more, it uses the burner less, thus saving energy.

Start Your Operation With Quality Equipment

Reliant Finishing Systems is a U.S. leading manufacturer of efficient and affordable powder coating equipment, from small batch systems for rims and wheels to large automated systems for constant throughput and rapid production. Whether you need to replace your existing coating equipment or are bringing a new operation in-house, our systems specialists can help. Give us a call today.

If you are looking for more educational information, please check out our Resources page.

 

Switching From Liquid Paint To Powder Coating: What You Need To Know

Powder coating is a more economical and longer lasting alternative to traditional wet paint application with far less environmental impact. If you’re comparing these two finishes from a production standpoint, here’s what you need to know.

Powder Coating Is More Durable Than Liquid Paint

Powder Coated Pipes

Powder coated items are more durable and last much longer compared to liquid paint.

Switching from liquid coating to powder coating has many advantages. From a performance perspective, powder coating is more durable physically and chemically. Most liquid coatings are typically softer than an average powder coating. When coating parts like semi-truck wheel rims, this improved durability and corrosion resistance make trucks safer and longer-lasting. In the oil fields, replacing corroded pipes or junctures is expensive and leads to oil flow downtime. These parts and fixtures are perfectly suited to powder coating and benefit from its performance advantages.

Powder Coating Is More Efficient & Easier To Use

If you’ve worked with liquid paint, you know that mistakes can be time-consuming and costly. In comparison, powder coating is generally much easier to apply. Operators require less training to apply a quality finish and mistakes can be easily fixed with powder (as long as you catch them prior to curing). Since rework issues are fewer and coating is usually faster, you can coat more items on a given day. You can expect increased throughput with fewer errors by switching to powder coating.

Most Importantly, Powder Coating Is Cheaper  

Cost savings are another great benefit to powder coating and often provide a very fast return on investment.

Since everyone has different size and shaped parts they need coated, we can determine ROI by calculating a 1 square foot panel cost. For this example, we’ll eliminate the labor and fixed costs and focus on just material costs. This will show the cost savings of powder coating versus liquid coating.

For our examples, I’m going to compare the amount of powder versus the amount of liquid paint to cover a 1’ square at a standard 2.5 mils. The mil, or thousandth of an inch .001, is most commonly used in engineering or manufacturing. It is used to specify the thickness of items such as paper, film, foil, wires, paint coatings, latex gloves, plastic sheeting, and fiber. (For example, most plastic ID Cards are about 30 mils in thickness.)

I’ll be calculating material costs using the coverage formula:

192.3 / Specific Gravity / Film Thickness = Coverage (Square feet per pound)

Let’s use a 1.4 specific gravity powder at 2.5 mils. The powder costs $4 a pound and we calculate our transfer efficiency at 70%. 192.3/1.4/2.5 = 55.2 coverage at 100% TE. 55.2 * 0.7 = 38.64. $4/38.64 = $0.10.

It costs $0.10 for a powder coated 1 square foot panel at 2.5 mils.  (For more info, Akzo Nobel has a great online calculator to do this at: http://www.interpon.us/our-coatings/powder-coverage-calculator/)

To get the same 2.5 mils DFT in a traditional liquid polyurethane, it will take a different calculation. Coverage is:

 ft2/U.S. Gallon = (%Solids/100 *1604)/ DFT (For a more comprehensive description of the liquid paint coverage formula: http://www.wellservicingmagazine.com/featured-articles/2007/11/applied-cost-a-useful-tool-in-paint-purchases/)

So to get 2.5 mils DFT with 45% solids polyurethane, 1 gallon can cover 289 square feet at 100% transfer efficiency. The average price for catalyzed polyurethane is $55, so at 50% transfer efficiency we get:289/2= 144 ft2 coverage and $55/144 = $0.38 paint cost per square foot. 

It costs $0.38 for a liquid coated 1 square foot panel at 2.5 mils.

Note these are only material costs. Liquid coating usually takes multiple passes and has much longer dry time. Flammability and waste disposal are also a concern for liquid coating operations.

In this example, the powder costs 3 times less. If a liquid coating operation uses $100,000 a year on paint costs, they can cut their paint expenditure by $50-60,000 being conservative. That difference is the price of a nice medium sized powder coating batch system.

Can I Use Liquid Paint Booths For Powder Application?

Powder coating equipment reliant finishing systemsWhile it is certainly possible it is definitely not recommended. Liquid booths are geared for a larger airflow pull than their powder equivalents. Too much airflow and you start pulling powder away from the part. This wastes money. Also, if you plan on continuing your liquid operation, you do not want to use powder and liquid in the same booth. It plugs up your filters fast and is a safety hazard if you are using solvent based liquid paint.

In future articles, I’ll be explaining more of the differences between liquid paint and powder coating, including specifics on transfer efficiency, waste, and energy savings. If you have any questions at all, or any topics you’d like me to cover, please e-mail me at bruce@reliantfinishingsystems.com

Looking for more information on powder, powder coating and application techniques? Please visit our growing list of articles on our Resources page.