Powder coating is a type of coating that is applied as a dry powder to a surface and then cured under heat. The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional liquid coatings, which can be used on plastic, glass, or metal surface.
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The powder coating is usually done by electrostatic spray deposition (ESD) or fluidized-bed application. Both two methods provide great gloss levels, textures, various colors, and high-quality surfaces, making them used on a variety of products, including medical devices, architectural applications, automotive, and even fiberboard avionics.
Powder coating is usually divided into two main categories. There are thermoplastic, thermosets. In addition, there are also divided into three categories, including Thermoplastic, Thermoset, and UV Curable Powder Coating. The UV curable is the most advanced technique.
This article will introduce three types of powder coatings. You can decide which type to choose based on the parts’ materials, durability, cost-effectiveness, and quality.
Thermoplastics are those which soften with heating and can be processed after that to gain specific strength and chemical properties with cooling. In thermoplastic powder coating, the dry powder is coated on desired part/material with heating the powder melts and covers the desired workpiece, and gains the specific mechanical strength on cooling.
Specifically for industrial purposes, thermoplastic coatings are implemented for endurance, esthetics, and safety purposes. Some of the thermoplastic powders used in the industry are mentioned below.
Nylon
Nylon is an excellent thermoplastic powder coating material with excellent durability and impact resistance. It is FDA approved and food graded, that is why it is commonly used in household and kitchen products such as dishwashers and for food storage items. It also has a low friction coefficient, which makes him ideal for the surface finishing of gears and mechanical Tools.
Polyvinyl Chloride (PVC)
The PVC coating is introduced in the market when the powder coating is in its initial stage, these coatings are pliable, sleek, and durable and show resistance to most of the solvents. polyvinyl-chloride is engineered with the polymerization technique in the presence of vinyl chloride, and it is produced in the industry on large scale. The basic benefit of these coating is in terms of chemical and electrical insulation. Moreover, they have excellent spray resistance, FDA-approved food staining resistance, and good dielectric and physical strength.
Polyester
The polyester coating is famous for its durable finish, weather and temperature resistance, esthetic look, and for its resistance to abrasions. For these reasons, this type is mostly used for outdoor automobile and avionics parts. Due to their aesthetic looks and physical strength, they are also ideal for architectural purposes.
Acrylic
Acrylic powder coating shows high-quality surface esthetics and high impact resistance, this process needs a little bit high curing temperature, that’s why it is mostly considered an expensive powder coating.
It shows excellent alkali resistance which is ideal to be used for components like washing machines and ship structures. Acrylic powder coating is applicable through electrostatic spraying to get ideal chemical resistance, weather ability outstanding smoothness, physical strength, and durability.
In thermoset powder coating The thermoset resigns are broken down to powder material, Which is fabricated on the desired material as a thin film. They provide improved chemical and physical characteristics in the aspect of esthetics, and corrosion resistance than ordinary oil coating.
In the modern, the thermostat material technology improved a lot, The ability to engineer thermostats resigns to increase their physical and chemical properties as per the targeted object, improving this niche a lot in specialized roles in surface finishing technique. The following are two common thermoset materials.
Epoxy
Epoxy is a type of thermoset powder coating that uses epoxy resin as the binder. Epoxy-coated surfaces are hard and brittle in nature, they are not good weather-resistant and mostly got dull with the passage of time. Due to these factors, they are mostly applicable to those materials which do not interact with direct UV light. But they show excellent durability, chemical resistance, and adhesion properties, which are often used in industrial and commercial applications where these properties are required.
Epoxy-polyester hybrid
Epoxy-polyester hybrid powder coatings offer the benefits of both epoxy and polyester. They have excellent chemical resistance and durability, making them ideal for a variety of applications. These powder coatings are also able to resist UV light and abrasion, making them an excellent choice for outdoor applications.
UV curable powder coatings are a coating that cures under ultraviolet light. Unlike traditional methods, which require heat to cure, UV curable powder coatings can be cured at much lower temperatures. This makes them ideal for use on delicate or heat-sensitive materials. It also has a shorter curing time than traditional powder coatings.
UV curable powder coatings provide a number of advantages over traditional ones, including faster curing times, improved durability, and greater flexibility in terms of color selection. They are typically more expensive than traditional methods, but the improved performance can justify the additional cost.
The powder coating mechanism is divided into different stages that are essential for smooth and high-quality work. The whole working process can be divided into three steps.
If you want a smooth and high-quality surface finishing of your workpiece, you need to implement some pre-treatment techniques, the presence of dust, oil, and grease pigments affects the coat on the material, so the workpiece should be treated accordingly.
If your workpiece is covered with derbies like pre-existing paint, and rust then you need to process it in a blast room, the room mechanism uses compressed air to blow up all the unwanted debris from the workpiece, The pressure, and the conditions are chosen as per required conditions. if the workpiece is covered with excessive pre-exist paint then might need iron blasting for that.
On the other hand, if your workpiece contains strains of oil, grease, or another chemical solvent then it is essential to wash it with some chemical like iron phosphate for steel, zinc phosphate for galvanized steel, and chromium phosphate for non-chromium treatments. other than these ordinary pre-treatment procedures many other new groups of technologies are used these days, that use transitional metals and other organo-metals are used with the formulation of zinc sulfate, these procedures are ideal for cost reduction, and for a low uniform finish.
Powder coating application is also done in various ways that are decided as per the production necessity, price bracket, and materials selection, the two most common methods are electrostatic spray deposition and fluidized bed powder coating.
In the electrostatic deposition method, the charged powder particles are deposited on the workpiece by the electrostatic process, The application process of an electrostatic charge spray gun, a powder feeder, and a powder spray unit, The electronic spray gun is both operated manually or through computer numerical control and it gives charge to the powder through the HIT generator. When the application process starts, the electrostatic spray gun starts spraying negatively charged powder.
These charged Particles are thrown toward the positively charged grounded workpiece and got stuck at the surface of the workpiece due to the presence of electrostatic attraction. The workpiece is heated after powder deposition for some time for a smooth surface finishing. To produce thicker coatings one has to repeat or cycle or adjust the spray accordingly.
The parts of electrostatic powder coating are widely used in a variety of industries, including automotive, architectural, furniture, and appliances. It offers a number of advantages over traditional liquid paint finishes, including better durability, improved resistance to chipping and scratching, and a smoother overall appearance.
Unlike ESD, the fluidized bed powder coat is a type of powder coating that uses a fluidized bed to apply the powder coating to the workpiece. The workpiece is placed in the fluidized bed and the powder is applied to the workpiece using a spray gun. The powder is then cured using heat or ultraviolet light. The fluidized bed helps to evenly distribute the powder over the workpiece and the spray gun ensures that the powder is evenly applied.
The fluidized bed powder coat is a durable finish that is resistant to chipping, scratching, and fading. It is also a low-maintenance finish that does not require polishing or waxing.
Finally, the electrostatically deposited or fluidized bed powder coated part is cured in the curing oven for several minutes, the curing schedule depends upon the parts, materials, and the finishing requirements, The thick film parts take more time than thin-film parts. Normally the ideal curing time is 10 to 20 minutes with 350-400 degrees temperature. It melted the powders under these conditions and gives a smooth high-quality finish.
Powder coating is a far superior option to traditional wet paint for both protective and ornamental purposes; it provides a wide range of color options with a high-level surface finish, but it also has some disadvantages. Read on to learn more.
Durability
Durability is the key advantage of powder-coated parts, mostly the powder-coated material are resistive to fading, chipping, scratching, and wearing, They are ideal for physical strength, durable finish, and environmental resistance than spray painting.
They are ideally ultraviolent light protected, that’s all due to the engineered materials and other additives, unlike the conventional liquid coatings they are not faded out in an open environment, that’s why most automobile and aerospace industries use this technique.
Furthermore, rust issue is very much common for metal parts, the powder coatings provide stunning results for metals, it does not prevent the upper surface of the metal parts, but also prevents them from rusting for a long time. Anti-rust is the most famous property of powder coating than conventional paint.
Cost-effectiveness
It is a more cost-effective option than liquid paint. Although it has a higher initial purchase cost, it requires less energy to cure. Additionally, powder coating provides a more durable finish than liquid paint, which means that products coated with powder will last longer.
High quality
The powder coating finishes produce high-quality parts with a clean surface finish and modern aesthetics. The product’s physical strength, wear and tear resistance, and other properties have all been increased.
Environment-friendly
Powder coating is an ideal environmentally friendly method because it is devoid of all forms of harmful chemicals and solvents due to the presence of volatile organic compounds. Furthermore, This powder is applied to the surface and then cured under heat. The excess powder is then recycled, so there is very little waste generated by the process.
Higher initial costs
The initial setup cost of the powder coating industry is a little bit high, due to the high raw material cost. However, compared to conventional paint over a substantial amount of time, it is far less expensive, as traditional paint degrades after 1 or 2 years, whereas powder coat lasts for decades.
Powders can’t be mixed
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In the case of wet paint, one can mix multiple colors to create a new one that achieves the desired outcomes, but this is not possible with powder paint. Powders cannot be blended, they must be used separately. However, there is a broad choice of colors to pick from.
Thin coats
Powder coating is not ideal for thin coats, it can be operable to a minimum of 40 to 60 microns, if you are desired to do a much thinner coat than this, then it is advisable to use wet paints for better results.
Difficult to touch-ups
Touch-ups are simple to make with wet paints, but not with powder coats, since one must complete the entire procedure if a touch-up is required, therefore one must be an expert in this mechanism.
Due to high industrial benefits, these powder coating products have a wide range of applications in different industries, and their use is increasing by the day.
Automobile: Powder coating finishes are mainly used in all types of automobile industries, mostly it is used for the manufacturing of wheels, door handles, motorbike frames, Break components, radiators, metal surfaces, shock absorbers, oil filters, battery trays, and coils.
Architectural and Steel Industry: Due to their physical strength, corrosion resistance, high gloss, and aesthetic looks powder coated products are used in the architectural industry in stadiums, aluminum windows and doors, fencing, sheet metal, household appliances, and building facades.
Outdoor Applications: Due to its durability, ultraviolet light protection, and long-lasting, powder-coated materials are mostly used in the sports industry, agricultural machinery, outdoor products, and signs.
Electronics: Powder coating is widely used in the electronics industry. Powder-coated household wires, electric equipment, and daily electric tools are safer and more beneficial than a wet coating, this is all due to their modified properties of electroconductivity and electric dissipativity.
Medical Industry: In the medical industry, sterilized tools and smooth surface finishing are essential; powder-coated finishing is used on medical equipment, disinfection machines, etc.
Powder coating is a robust and long-lasting technology, there are several things that you can do to ensure that your coat finish turns out perfect. Here are a few tips:
This is probably the most important step in getting a good powder coat finish. If the surface is not prepared properly, the powder will not adhere well and will not give you the desired results. Make sure to sand or grind the surface smooth and free of any contaminants before you start powder coating.
There are different types of powder for different applications. Make sure to choose the right powder coating materials for your project. If you are unsure, consult with a professional powder coat finish company.
Picture framing is a common problem when powder coat finishes and can be caused by several factors. Most often, it occurs when too much powder is applied to the component, resulting in a thicker film around the edges. Other causes can include aiming the spray gun directly at the edges of the component, or having the gun settings set too high.
To avoid picture framing, pay attention to the spray dispersal and gun when applying the powder. Try not to aim at the edges directly, and watch the flow carefully to adjust your gun settings problem.
If you are using a powder coating gun, make sure that the tip is the correct size for the job. A too-small tip will result in the powder not being able to flow properly and will cause uneven coverage. A too-large tip will result in over-spray.
Also, you should have the correct voltage settings on your powder coating gun. Too much voltage will cause the powder to bead up and will not adhere properly to the surface. Too little voltage will result in poor coverage.
Curing is what actually sets the powder and gives it its final finish. Be sure to cure the powder according to the manufacturer’s instructions. This step is usually done in an oven at a specific temperature for a specific amount of time. Once the powder is cured, you need to inspect your powder coat finish for any imperfections.
Powder coating is a dry finishing process that uses finely ground particles of pigment and resin to give surface gloss levels and a consistent finish. It provides a more durable finish than traditional paint and is available in a wide variety of colors and finishes. If you are considering powder coating for your projects, you may need to spend lots of time getting the right expertise and experience to get the best results.
But no worries, here at WayKen, we offer professional finishing services to help you get the most out of the powder coating process. Our team has years of experience in providing cost-effective surface finish solutions for a variety of industries, so you can be confident that your parts will look great and meet your expectations. Upload your CAD files and let’s get started!
What is the difference between powder coatings and wet paint？
Both processes contain pigments, additives, and chemicals, however, the main difference is the presence of Solvent, Wet paint contains a solvent, that keeps him in liquid form, mostly wet paints didn’t show contraction and expansion, whereas the powder coat holds well on surfaces, and show contraction and expansion as per conditions., which makes him more durable and long-lasting
How much does powder coating cost?
The cost of powder coating depends on a number of factors, including the type of powder used, the size of the surface to be coated, and the complexity of the coating process. In general, powder coating is less expensive than traditional liquid paint finishes. The average cost for powder coating services is $75-$150 per square foot.
Why powder coat is better than conventional ordinary paint?
Powder coat is usually used to create a hard coating finish that is tougher than conventional paint. It is more durable than regular paint and can resist corrosion, chipping, and fading. It is also easier to apply evenly than regular paint and can be applied to a variety of surfaces.
Why industrial powder coating is green?
Powder Coating doesn’t use volatile organic compounds that contain methylene chloride, benzene, and formaldehyde. This is safer for painters and those who come into direct contact with the product. In addition, the powder itself doesn’t have any carcinogens or heavy metals. You can recycle powder coating materials and receive up to 92% of the original powder.
When I was a kid, my big brother took me to my first (other than animated) movie called The Dirty Dozen. It was an army movie where the government needed a few men to complete a very dangerous mission where it was likely no one would make it out alive. So they selected a team of misfits from the Army prison system and gave them a choice to continue to do their time or join this team.
The list of powder coating tips that follow are my own Dirty Dozen — misfits that are typically ignored, misunderstood or not given enough attention. Before we get started, let there be no mistake, there are many others — I simply selected these 12 from a list I created through the years and advice I received from fellow experts in the industry.
The reality is running a powder line has some procedures that are considered “must do” or nothing can be processed — but these items, the Dirty Dozen, can be handled poorly or even ignored in some cases, and you can still get powder coated parts. I want to go deeper into the top 12 aspects of powder coating that can take your operation to a new, improved level.
Keep in mind that many of these Dirty Dozen work together and with poor management of one, one or more of the others can be negatively effected.
The architecture of a specification could be the subject of an article on its own. I want to make it clear that writing a specification is a very important way to elevate your coating operation as it will become the tool by which you determine a pass or failure of the coated part. The specification clearly defines all the areas that will be measured to provide a quality product, explains how to measure those areas, and most importantly, identifies how to determine if a coated part is rejected. The specification, if written properly, should remove the majority of the subjectivity in the evaluation process. Your specification defines all the tests your coated product must pass to meet your expectations and/or those of your market. However, in order to start this process, two things must be known:
Make sure when developing your specification that you are not reinventing the wheel. Use templates your powder vendor can supply you, as well as ASTM test methods, AAMA guidelines, and guidelines from PCI and/or APCA, just to name a few.
If you only have a few dollars to spend on a powder system to improve your process, buy a film gauge. This is an essential tool for all powder coatings operations. Next, put together a process to measure your film build on each part. Once you start measuring and documenting what you have, you can then start finding areas to improve your control. The idea is once you start measuring something you can then start to manage said something,
First pass transfer efficiency (FPTE) is the amount of powder sprayed from a device that sticks to the part. The remaining powder can be reclaimed or sprayed to waste. First pass transfer efficiency has many facets starting with the setup of the spray gun(s) minimizing the speed in which the powder is sprayed, giving the powder the best chance to adhere to the part. Ground, gun to part distance, set up angles using lead and lag, air flow, part geometry and last, but in many cases not least, the powder formulation — a formula that has been designed for your application.
If the idea is to maintain a consistent, high-quality appearance with your powder coating operation, then the ability to have a particle size management program is very important. This starts with a partnership with your vendor on a particle size distribution specification — a process to manage your virgin powder to reclaim ratio, optimal line density and first pass transfer efficiency.
When wanting to increase productivity, the best, most efficient and practical way is to improve your line density or at least look at this first before you start increasing line speed. While increasing line speed will in fact push product through at a faster level, it also reduces the dwell time in all areas needed to produce an optimal powder coated part. On the flip side, increasing or improving line density allows your process to improve simply by increasing the amount of product in the given silhouette.
Many training programs include being trained from the old guy who was trained by the older guy who was trained by the dead guy. While it may work, this approach does not develop any consistency, structure or true knowledge transfer. What you want to create is the ability to assure whomever is doing the job is doing it the same way every time. Develop training programs, use videos to make points and assure the new guy does it the same way as the next guy.
Once you understand the atmospheric conditions your part will be subjected to and have defined an idea of how long you want it to last in that atmosphere, you have a very good starting point. With only this information, you can narrow down to the field to if powder coating with UV resistance is required or not. From there, you take one performance requirement at a time, removing chemistries along the way.
When selecting a powder coating, the use of layers should also be considered. Additional layers can provide increased protection for times when the atmospheric condition is more harsh than what you may consider a normal application — all without the need to change your standard powder coating. The use of layers allows you to offer two performance options and allow the consumer to select the ones that will best suit their needs.
One of the most missed or ignored parts of a powder coating process is looking at the way a component of a product is engineered and/or fabricated. Look at how and where welds are placed and consider whether the part has hidden areas where powder or pretreatment will not be able to reach or protect. By taking time to consider the part design itself, you can assist your powder coating in its goal to help the part or product last longer.
In any powder coating operation, there are many air sources and they all should be checked regularly, before it’s too late. First is compressed air where not only the PSI (pounds per square inch) needs to be adequate, but also CFM (cubic feet per minute) — the volume must be maintained. But what about LFPM (lineal feet per minute) — the velocity of air moving throughout the opening of a powder booth? Your regular maintenance program should check these areas before you see an issue.
When you have trouble (and you will have trouble) — what process do you use? The natural impulse is to start turning knobs until the problem goes away. If this works (and in some cases it may), it only shows that you have turned the correct knob. In the process, you have also most likely turned a knob or two that were not needed to address the problem and will impact something else. The best and most practical way to troubleshoot is to use the SIRE method.
The SIRE method allows you to take the time and find the root of the problem by using the process of elimination.
I left this one for last, but it should be considered as something you do in the beginning: Pick good partners to join you in the journey. Your application equipment partner, your powder coating vendor and/or your chemical pretreatment supplier — all of these organizations want you to have an optimal, self-sustaining process and have expertise in-house to help you get there!
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