Before we go into the specifics of the process on how powder coating is applied, let’s take a moment to cover powder coating as a whole. Powder coating stands out as one of the most recent advancements in surface finishing techniques popular today. It emerged as a novel finishing method during the s, and its environmentally friendly benefits make it the leading choice among coating systems due to its solvent-free composition. This technology can achieve a coating thickness of approximately 2-4 mils with a single coat, demonstrating exceptional efficiency in material usage.
ZHYAO Product Page
Furthermore, powder coating delivers robust mechanical properties and exceptional edge protection, ensuring that the finished product retains its integrity and appearance. Notably, this finishing method consistently yields optimal results with just one application. Additionally, it minimizes waste through its remarkable overspray recovery rate, which can reach up to 95%. All in all, powder coating proves to be a cost-effective choice, benefiting both the environment and your budget by reducing material and application expenses.
1. Steel: Steel structures are one of the most popular substrates for powder coating. It's durable, strong, and versatile, making it a prime choice for various industries. Powder-coated steel is commonly seen in automotive parts, appliances, outdoor furniture, and industrial equipment. Its ability to withstand harsh environmental conditions, such as exposure to UV rays and moisture, makes it a reliable option.
2. Aluminum: Aluminum is another highly favored substrate for powder coating. It boasts lightweight properties and excellent resistance to corrosion, therefore an ideal choice for architectural elements, outdoor structures, and aerospace components. The smooth surface of aluminum allows for a flawless powder coating finish, enhancing its aesthetic appeal.
3. Wood (MDF): Wood substrates, particularly Medium Density Fiberboard (MDF), have gained popularity in recent years for powder coating applications. Powder-coated wooden surfaces are used in furniture, cabinetry, and interior design, offering an extensive color palette and a durable finish. Powder coating provides an eco-friendly alternative to traditional wood finishes.
4. Plastic: Powder coating on plastic substrates is another innovative approach. It enhances the durability and scratch resistance of plastic materials while providing a visually appealing finish. Examples for powder coatable plastic substrates include polyamide and our own 3D-Set material for SLS 3D-Printing.
5. Pultrusion (Composite Material): Pultrusion is a composite material crafted from fibers and resins. This strong and lightweight substrate is highly corrosion-resistant, making it suitable for challenging environments. Powder coating on pultrusion materials is often found in structures like bridges, handrails, and offshore platforms, where durability and longevity are paramount.
In essence, powder coating provides a versatile and durable finish for a diverse range of substrates. The choice of substrate depends on the intended application and the specific qualities required, from the strength of steel and aluminum to the aesthetic possibilities of wood, glass, and plastic, and the specialized attributes of pultrusion and ceramic materials. Whether for functional or decorative purposes, powder coating offers a solution for enhancing the performance and appearance of countless products and structures.
Powder coating is a dry finishing process that involves the application of fine, electrostatically charged powder particles to a substrate's surface. This application method ensures an even and consistent coating, free from drips, sags, or unevenness.
Before applying the powder, the substrate must undergo thorough cleaning to remove any contaminants like oil, grease, or rust. This crucial step ensures proper adhesion and a flawless finish. The substrate is freed from dust, scale, rust, grease, dirt, and any oxide layers (for example on aluminum). There exist chemical and mechanical pre-treatment processes. To increase the corrosion protection and improve the adhesion of the powder coating a conversion layer is created on the piece during the pre-treatment. Following this, the workpiece must dry completely.
Cleaning Methods: The cleaning process involves the use of weak alkali and neutral detergents, often in dip tanks or wash stations. These stations are equipped to spray parts with hot water, steam, detergents, and other pretreatment solutions to clean and chemically prepare the surface before coating. They ensure a spotless foundation for your powder coating.
Masking Methods for Precise Applications: Sometimes, parts require specific areas to remain uncoated. This is where masking products like masking dots come into play. They're available in various shapes and forms, generally constructed of paper or plastic film coated with a pressure-sensitive adhesive. These nifty tools adhere to the substrate, safeguarding the covered areas from meeting the powder material during the coating process.
The Role of Chemical Pretreatment: Chemical pretreatment involves the use of chemicals to clean the surface, which promotes adhesion of the powder coating to adhere on slick or difficult metals. This process is typically carried out using a series of spray nozzles or an alkaline immersion dip. Parts undergo multiple stages to ensure optimal surface preparation. Chemical pretreatment processes can either be automatic comprising of a conveyer line with multiple stages or manual operated using spray parts with wands or hoses.
First, the substrates are cleaned using an alkaline, acidic, or neutral cleaner (generally alkaline). Following this, parts are surface treated with a conversion coating, after which an acid etches the surface to prepare it for subsequent operations. The specific type of conversion coating can vary based on the material being coated and the desired properties of the final product.
A rinse stage is typically included between each pretreatment stage to remove any residual chemicals and contaminants. Lastly, a RO (Reverse Osmosis) or DI (Deionization) Rinse is applied to improve coating performance and reduce pretreatment chemical usage. It is important to note however that this rinse shouldn’t contain any chlorides or fluorides to prevent further chemical contamination.
Mechanical Pretreatment for Tough Contaminants: Mechanical pretreatment involves the use of abrasive media which essentially means rubbing or grinding to polish or clean a substrate. For certain applications where inorganic contaminants like rust, mill scale, and laser oxide need removal, this pretreatment method is preferred. Techniques like sand or shot blasting use high-velocity air to drive abrasive materials (like sand, grit, or steel shot) toward the substrate. This creates an anchor pattern on the part's surface, significantly improving the adhesion of the powder coating to the substrate. Several different types of abrasives are available, and their use depends on the type of finish and contaminant to be removed. For instance, Walnut shells would be used for de-burring while plastic grit will be used to remove paint. Similarly, glass beads are preferred if the end goal is to get a matte and satin finish.
Mechanical cleaning can be used independently or alongside a chemical treatment. While it enhances adhesion, it does not offer additional corrosion protection. In many cases, after mechanical blasting, the surface is coated with a suitable primer to add extra corrosion protection. The primer may also incorporate zinc-containing materials for further enhancements.
Spray systems are pivotal in the powder application process, offering efficient and precise coating application across various surfaces and part geometries. Spray systems in powder coating include components such as the powder hopper for holding the coating materials, an application gun for spraying, a feed system for transporting the powder from the hopper to the gun, a control unit that regulates and fine-tunes various application parameters, as well as air-supply and recovery systems. So, what makes a good powder coating spraying system? Let’s find out!
A notable characteristic of effective spray systems lies in their field-serviceable design and utilization of quick-turn components. This strategic approach simplifies maintenance procedures, leading to reduced downtime and ensuring a continuous, reliable performance throughout various coating tasks. When considering spray systems focus on adaptability as well and choose ones with versatile configurations, as they offer flexibility to cater to diverse coating requirements.
An innovative pump design is another important consideration as it further enhances the functionality of the overall system by optimizing energy consumption, contributing to both efficiency and sustainability in coating processes. Lastly, all-digital control unit are becoming more common, providing precise control over electrostatic and pneumatic settings. This level of control is crucial in achieving optimal coating performance, ultimately leading to the production of high-quality finished products.
In contrast, fluidized bed powder coating is somewhat different. Here's how it works:
Employing oscillators, reciprocators, and robots to manage spray equipment offers cost savings and ensures consistent coverage in numerous applications. Gun triggering, which involves automatically turning the spray gun on and off based on part positioning, reduces overspray, leading to reduced material consumption.
Grounding is arguably the most important aspect of a successful powder coating application. We’re saying “arguably” because this is a subjective statement and for some other factors may be more important whether that be the spraying system or the powder itself.
From a safety perspective, ungrounded parts can accumulate charge, posing a risk of electrical discharge when approached. This discharge can not only be startling but also hazardous. Discharges across small distances between charged surfaces and ground can contain enough energy to ignite the powder being sprayed from the gun, further emphasizing the safety aspect.
On a quality level, maintaining a solid ground is crucial for achieving consistent film thickness and uniformity in powder application. Issues such as Faraday cage penetration and back ionization can arise without proper grounding. A study conducted by Kolene Corporation highlighted that maintaining an excellent ground during the powder application process significantly improved powder-coated surface topography.
Lastly, from a cost perspective, poor grounding adversely affects transfer efficiency and minimum film thickness. Inefficient grounding can result in excessive powder usage to achieve the desired film thickness, leading to increased waste and expenses.
To ensure effective grounding, it is essential to have a traceable path from the part to the powder coating earth ground rod, with no breakdown in electrical conductivity. Using an 8 to 10-foot ground rod, preferably longer in high resistivity soil conditions, and measuring resistance between ground rods can help ensure a reliable ground. Employing solid copper ground bars of appropriate length further enhances the effectiveness of the grounding system. Overall, proper grounding is a critical factor in achieving both safety and efficiency in powder coating applications.
What if you want to powder coat the same substrate twice? Well, that's exactly what the two coat process is. The two-coat process involves applying two coatings onto the same substrate, aiming to improve the finish's appearance while safeguarding it from environmental factors. This method, particularly prevalent in powder coating, presents various applications demanding precision and technique. Partial curing emerges as a pivotal technique, facilitating optimal crosslinking and adhesion between the coats.
So, how does the two coat application process work? First, the base coat undergoes pre-gelling at 392°F (200°C) for 2-3 minutes, ensuring superior inter-coat bonding. Subsequently, the substrate cools to 175-200°F (79-93°C) before applying the topcoat, followed by a full curing cycle. Common scenarios employing partial curing include primer with a topcoat for enhanced protection and clear coat atop a basecoat for aesthetic modifications. Specialized two-coat methods like Candies, Chromes, and Metallics necessitate adherence to specific curing parameters to achieve desired effects. Additionally, meticulous attention to timing and contamination prevention is imperative for optimal outcomes. Remember, consulting manufacturers and comprehending technical details are crucial for successful two-coat applications.
To grasp the intricacies of this process, delve into our detailed blog regarding the two coat process for insights and tips.
After application, the coated substrate is subjected to high temperature curing in an oven. During this process, the powder particles melt and fuse, forming a robust and durable finish. The powder coating is cured in an oven at temperatures between 110 and 250 °C. Various factors such as heating time and substrate thickness affect the final curing time. Thermoset powder coatings require specific heat energy and time to trigger the chemical reaction needed for cross-linking into a film. When exposed to heat, the powder material melts, forms a smooth film, and starts to cross-link, eventually reaching full cure. Different methods can be employed to provide the necessary energy for curing.
Convection Ovens: Convection ovens use a heat source (typically natural gas) and a fan to circulate heated air through an oven's duct. The hot air transfers heat to the part and the coating. This is the most common type of oven for powder curing. As the part reaches the desired temperature, it conducts heat into the coating, leading to powder curing.
Infrared (IR) Ovens: IR ovens use gas or electricity as an energy source to emit radiation in the IR wavelength band. This radiation is absorbed by the powder and the substrate directly beneath the powder without significantly heating the entire part. This approach enables a quicker temperature rise, causing the powder to flow and cure when exposed for a sufficient duration. However, curing uniformity may be influenced by the part's shape and density.
Radiation Curing Technologies: These include near-infrared, ultraviolet (UV), and electron beam (EB) processes. These technologies offer potential applications for powder coating on heat-sensitive substrates like wood, plastic parts, and assembled components with delicate features.
Generally, powder coating operation lines are measured on their efficiency, scrap/defects, and waste generated. Ideally, you’d want a high-speed operation line with minimal rework, and material wastage. So, with that in mind, here are some tips to help you get there and make the most out of your powder coating process.
As powder-coating applications take the finishing industry by storm, clients are coming to Richards-Wilcox Conveyor for help designing, integrating and reconfiguring their own finishing lines.
These clients have a lot of questions about powder coating. But there’s one we’ve been hearing more than any other:
“When designing a powder-coating line, should I invest in a manual batch-type system or an automated line?”
The answer isn’t as clear-cut as you might think. In fact, it all depends on your workflow, your volume, your budget, and your floorspace.
Let’s take a closer look.
For those who don’t know, a manual batch-type system is the more hands-on variety of powder-coating production line. In batch systems, operators begin by manually preparing parts, moving items from one device to another using carts or a manually operated conveyor. Once a batch of parts is ready, it is then coated and cured.
As the name suggests, an automated line automates this process. Rather than using human labor to prepare batches of parts, an automated conveyor system continuously moves individual parts through the entire process, from prep and drying to application, curing and cooling.
So, which is better: manual batch or automated?
The truth is that neither system is inherently better—both have their benefits and drawbacks. One is more efficient, while the other is more flexible. One is more expensive, while the other is more labor-intensive.
How do you find the right system for you? Start by considering these four factors.
In general, automated lines are best suited to coating higher volumes of parts, as long as those parts have consistent sizes and shapes. If you’re coating thousands of similarly sized parts per shift, automated is probably the right fit.
Batch systems are typically slower than their automated counterparts, but they’re also more versatile. While automated systems must be reconfigured to account for irregularly shaped parts, manual systems don’t. It may be more efficient to go manual if you’re working with lower volumes of irregular parts.
Manual systems typically require fewer components – for example, one oven can be used to both dry and cure parts – which makes them a good fit for businesses with limited floorspace.
However, just because you’re tight on space doesn’t mean an automated line is impossible. Richards-Wilcox Conveyor has worked with clients to make automated lines fit in surprisingly limited spaces.
Manual batch systems are generally slower than automated. If your powder-coating system outpaces the manufacturing process, then that may not be an issue. But if your powder coating process is delaying output, then you may need to speed things up with automation.
Automated lines can be designed for rapid throughput, creating a constant flow of parts to keep pace with other manufacturing processes. If you need speed, go automated.
Manual batch-types systems are typically seen as the budget-friendly alternative to automated lines. The upfront cost of manual systems is significantly less; and although they require more human labor, their maintenance costs and operating costs are often much lower.
Then again, the relative efficiency of a system all depends on the other three factors we listed here. If your system is operating at full capacity, producing thousands of products per shift and keeping pace with your other manufacturing processes, an automated line may be necessary to help you meet production goals.
Whether it’s a smaller manual operation or a large-scale automated line, Richards-Wilcox can create a system that maximizes your efficiency and helps your business achieve its goals.
From designing layouts and installing conveyors to integrating robotics and automation, we leverage decades of experience and key partnerships to create the right solution for your needs.
For more Manual powder coating lineinformation, please contact us. We will provide professional answers.
Learn more about our work with finishing line systems.
We are interested in installing a powder coating line. What should we consider? B.R.
I have advised many future powder coaters, written several articles and taught many seminars on this very topic. The most often asked question is “How much is it going to cost to convert to powder coating?” It seems that this simple question would have an equally simple answer, but it doesn’t. That’s because every powder coating system is custom designed using standard components to meet specific quality, performance, part size and production requirements. “Right-sizing” your powder coating system ensures that you end up with a process that will accommodate your products in the volumes you need to produce at the quality your customer expects.
You should consider several issues before you purchase a powder coating system:
Will powder coating work with your product? This may seem obvious, but you should verify that there is a powder coating material available that meets all your functional performance and visual appearance objectives. Next you should verify that your products can be powder coated (Can your products conduct an electrical ground of less than one megohm for safe electrostatic powder application or handle preheating for flocking applications? Can your product withstand the cure temperature for standard powders or the flow temperature for UV curables?). If the answers to these questions are yes, then proceed to the next issue.
Is powder coating economical for you? There are operational cost analyses that can be preformed to determine if powder coating can save you money or cost you more. Most of the time powder coating will be less expensive than liquid coatings, but running the numbers will ensure that you won’t be surprised after you install the equipment. The Powder Coating Institute (PCI) has a spreadsheet application that will assist you in determining the operational cost of a powder coating system and will allow you to compare this cost with your existing or a competing finishing technology. You can obtain the spreadsheet free by calling PCI at 703-684-.
Do you have some equipment in your existing finishing process that can be used to support the new powder coating process, or must you buy a completely new system? If some of your equipment is compatible for use in your new powder coating process, is it in good shape? You can certainly reduce the cost of converting to powder coating if some of your finishing system components are compatible to the new process (washer, dry-off oven, cure oven, etc.)
Is there a Return on Investment (ROI) or payback target that needs to be met? You can obtain budgetary quotations for the equipment and installation costs of your new system and use the operational cost/savings analysis (see No. 2) to determine the ROI or payback for the new powder coating process. Compare your answer to your target.
At this point, you have addressed all the preliminary issues that need to be answered before you can determine if powder coating is right for you. Several issues will affect both the size and cost for your new powder coating system. We will deal with these issues individually.
How many parts do you have to coat per unit of time? What is the optimum hang pattern for these parts? What effect will downtime for color change have on the available production time? Is there future production growth that needs to be accommodated? What will be the anticipated reject rate from this process? These issues are used to determine if a batch or conveyorized operation can support your production needs. Also, if your process is going to be conveyorized, these issues are used to calculate line speed.
What is the aggregate part size for your new system? This aggregate part size is the height of your tallest part, the width of your widest part and the length of your longest part. Often these three dimensions do not occur on the same part.
What is the product quality you are looking to achieve with this new powder coating process? The quality issues that need to be identified are:
a. Corrosion requirements will affect the pretreatment system configuration (number and length of the washer stages).b. Appearance requirements will determine if an environmental room is necessary.
c. Coating requirements will determine the configuration of the cure process (IR, UV, convection, temperature, time, etc.)
d. How many colors will you be using and will these colors be reclaimed or sprayed-to-waste?
The above-mentioned issues size every powder coating system. In powder coating, the bigger the system, the higher the cost. Since most of the powder coating process is time dependent (i.e., washer stage duration, cure time, dry-off time, etc.), the faster the line speed the larger the equipment and the higher the equipment costs. Furthermore, the larger the product the more equipment is necessary to coat it and taller equipment also increases system cost.
Careful consideration of the issues discussed here will ensure that you obtain a system that is “right-sized” for your needs. A system that is too large will mean that you spent too much for it and will penalize you every minute of operation because it is more costly to operate. Conversely, if you undersize your powder coating system it will become a bottleneck, causing all sorts of production scheduling problems.
Removing Cured Powder Coatings
Question: What methods are available for removing cured powder coatings, and what are the pros and cons of these methods?
Anodizing Vs. Powder Coat
I am an engineer on a large yacht build project and urgently need information and advice on choosing a finish for the aluminum deck plates in the engine room.
Calculating the Cost of Powder Coating
How can you calculate the cost of powder coating a component if you only know its surface area? Powder coating expert Rodger Talbert has the answer.
Traffic coatings are a useful tool for preventative maintenance on busy surfaces. As the first line of defense against the elements and physical contact, coatings serve a critical role in protecting against damage and deterioration to high-traffic pedestrian and vehicle contact surfaces.
Various coatings offer robust applications with traffic slip resistance, aesthetic appeal and intensive waterproofing. From an engineering perspective, coatings are valued for their ability to prevent premature deterioration and wear while increasing the longevity of road surfaces, pedestrian areas and vertical construction.
The major upside to utilizing traffic coatings is the protection of underlying materials and ability to negate physical damage. It’s always worth exploring traffic coatings in-depth to determine if an application is right for your project.
When examining traffic coatings, ask these simple questions to get started:
What are you trying to accomplish?
What is the substrate material?
What is the surface condition currently?
What is the exposure?
In terms of outcomes, durability is often a top priority. Slip resistance, waterproofing and appearance are also frequent causes for implementing a coating. The substrate material and general condition will also influence the coating selection and the ability to actually deliver protection. Too much wear and deterioration on a surface will benefit from resurfacing or patching before the installation of traffic coatings.
Lastly, the exposure determines the necessary robustness of traffic coating systems. Pedestrian-only surfaces can benefit from a light pedestrian traffic coating while high-traffic vehicle contact and heavy equipment exposure will call for a heavier application.
The general benefits of implementing traffic coatings are:
Protection of substrate (building materials)
Reduced surface repair costs
Sustainability of the road surface
Extended warranty offered for coatings (5 years)
While the few cons include:
Upfront costs for material and application
Difficulty finding certified contractors
Potential to choose the wrong coating
Most engineers agree that the pros outweigh the cons. Upfront costs are often an issue but when traffic coatings are selected and applied by experienced and certified contractors, the long-term protection and return on investment are advantageous.
Traffic surfaces vary in material construction and traffic types. The appropriate traffic coating type is determined based on these factors. In order from lightest to most intensive in application and protection, you will encounter penetrating sealers, cementitious coatings, urethane coatings, and heavy-duty epoxy overlays.
Light penetrating sealers are excellent for vertical structure applications but also for light horizontal traffic surfaces. They are the most cost-effective at less than $2/square foot and are excellent for masonry and cement-based structures. Penetrating sealers are breathable so no vapor lock is experienced but they still provide a layer of waterproofing.
As the lightest application, penetrating sealers are not designed for high-traffic, horizontal surfaces and they will not provide slip resistance. They do however fend off chemical contact that rapidly deteriorates masonry and concrete structures.
Designed for higher-traffic areas, this application is cement-based and waterproofing and chemical resistance are two of the major benefits for vertical and horizontal surfaces. It offers a low VOC which is less odorous on application. The breathable properties prevent vapor lock and the application options are wide. It works very well for vinyl, wood, cement, masonry, pool decks, marble, and more. The three- to five-year lifespan is attractive and the only downside is a lack of elasticity. Surfaces with high flex will benefit from a more elastic coating that will not delaminate or debond on flexible surfaces where structural movement is anticipated.
Urethane top coatings are the most popular traffic coatings designed for high-traffic, horizontal applications. They work equally well in occupied or unoccupied spaces and are common on elevated parking structures or over top of occupied spaces. Urethane provides excellent waterproofing alongside minor chemical resistance. The concrete and rebar receive significant protection, extending the overall lifespan.
Flexibility and UV stability make urethane very durable in a variety of environments. Aesthetically, it will maintain color and as an integrated topcoat, installation is less labor-intensive while providing a fully encapsulated, evenly distributed aggregate. Slip resistance is an attractive property for elevated parking structures as well.
Note: Not all urethanes are integrated topcoats. The option is specific to traffic coatings.
Urethane coatings do require annual maintenance, especially after contact with snowplows and heavy equipment. Overall, the coating has few cons and offers an effective means of protecting high-traffic surfaces.
The highest level of durability and protection offered comes in the form of epoxy. Urethane remains more popular but epoxy offers custom mixtures and aggregates available for utilization across a wider range of surface types. The ability to customize and increase slip resistance and add bigger aggregates makes epoxy unique.
Epoxy can withstand high levels of traffic and abuse, making it a great solution for parking garages, pavement parking, DOT applications and warehouse floors. The material is breathable, preventing vapor lock and it looks great aesthetically. The application is rigid and is best used on low-flex surfaces.
Want more information on Semi automatic coating line? Feel free to contact us.