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Technology Interchange - Emerging Powder Application Technologies

Posted on Monday, December 10, 2018

To review the latest developments in application technology, these advancements have been delineated into the various components of a powder spray system including guns, delivery devices (e.g. hoppers, pumps, hoses, etc.), reclaim systems and gun movers. Color change technology and equipment specifically designed for non-traditional substrates is also included. Some really cool developments have emerged, ranging from something simple and perhaps obvious, like an LED light attached to a manual gun body, to sophisticated electrostatic charging systems.

Gun Design

One innovative advancement focuses on powder application technology with a unique rotating electrostatic powder bell applicator. The rotating bell sprayer reportedly delivers high performance, excellent finishing quality and easy integration. It also provides high transfer efficiency rates with easy maintenance. This unique technology will be showcased at the FABTECH show in November.

Undoubtedly the most fun innovation is the integration of an LED light atop a manual spray gun. It’s so popular that it is now a standard feature for some manufacturers. Manual handguns with LED lights allow an operator to better see what he is painting. The LED light receives power from the multiplier residual field around the gun, requiring no additional power source. The light can be kept on for an additional 15 seconds after the trigger is released. This new innovation is said to have reduced reject rates and increased line speeds.

Some powder applicator equipment suppliers have focused on the efficiency of a gun’s charging mechanism, continuing to improve upon technology for high efficiency, advanced corona charging. The technology lets users get the full benefit of high voltage (high transfer efficiency) and low gun current, simultaneously using the latest modulation technology (same as used in motor speed controllers, welding equipment, plating lines, and light dimmers). In addition, electrostatic scientists are finding ways to optimize duty cycles and frequencies for a wide range of powder coating conditions.

Another interesting development utilizes light weight combined with low current operation which minimizes the generation of excessive heat in the cascade, making it much more efficient and less likely to breakdown due to high temperatures. Furthermore, these types of guns are well suited for use in dry-on-dry powder systems where back ionization and Faraday cage penetration are problems because they minimize high excess free ions on corners that can lead to powder pull back.

Delivery Systems

Dense phase pumping systems debuted about 10 years ago and continue to evolve. Today’s newer models have easier serviceability, featuring one screw disassembly and longer pinch valve life. Repeatability in dense phase pumps without having to adjust for wear of a venturi style pump throat drives user acceptance of this technology. The ability to have effective flow rate outputs, with higher transfer efficiency up to four times that of a traditional pumping system, make coating large and difficult parts more time efficient. Low air output at the front of the guns prevents powder from being blown out of Faraday areas.

Spraying and cleaning performance have improved with new application pump and electrostatic gun designs. This technology enhances powder application uniformity and consistency, boosting transfer efficiency and reducing the amount of powder that is sprayed. All of this increases material utilization and makes for easier and faster color changes.

In addition, there have been developments in advanced powder feed technology that features full, closed loop, real time feedback on powder flow to the gun. This technology allows users to “dial in” a powder flow and maintain that flow throughout all types of operating conditions in real time.

advances-in-coating

Advances in application technology have improved powder application and consistency, transfer efficiency and has made color changes easier and faster.

Color change

The issue of quick color change technology is nothing new to the powder industry. The difficulty of executing a swift color change in a powder booth has haunted application engineers for decades. Thankfully, major powder system designers have continued to bolster this technology, resulting in the ability to change color in as fast as 20 seconds (spray to non-reclaim) and five to 10 minutes in reclaiming systems. The limitation is in the payback based on volume of powder sprayed, not on the various equipment available to customers. Additional approaches center around sophisticated powder management as a key element of quick color change systems. Powder management centers and the latest booth designs work in conjunction to minimize the amount of powder that is in process, which enables the user to perform a color change quickly and easily with no risk of contamination.

Reclaim Systems

Innovations in reclaim systems have augmented quicker color changes. Time to change color is minimized with the use of automation and the elimination of as much powder in process as possible. This includes technology that automatically cleans the application system (pump, hose, gun), booths that constantly return overspray powder to the feed system, and feed systems that have small powder reservoirs to allow for faster, more automated cleanup at color change.

Gun Movers

Gun movement technology is not standing still. Gun oscillators and reciprocators are becoming as “smart” as possible by tying them to vision systems that can identify the part geometry and adjust on-the-fly based on size, shape and line speed. The use of robotics continues to grow with over 200 systems now in use in North America, mainly due to a significant reduction in price. The cost of installing a fully functioning robot is approaching that of traditional gun mover systems. Robots are easily reprogrammed as customer part configurations change, making them a more desirable solution than traditional gun mover systems with limited ability to access tight recessed areas.

Systems for non-traditional substrates

Interestingly, systems for non-traditional substrates such as MDF (medium density fiberboard) and plastic substrates are not a focal point for equipment suppliers. Not surprisingly, most electrostatic equipment that works for traditional metal substrates can work for application to more exotic substrates, including MDF, composites and plastics. The key to acceptable application is preparation of the surface to be coated. Non-conductive substrates require a conductive agent or coating to be applied prior to the powder application. MDF can be preheated to facilitate the attraction and deposition of electrostatically-charged powder. The reality is systems required for coating non-metal substrates are generally the same from an application and booth supplier standpoint. The limitation is in the prep and cure of the substrate, not in the application and recovery end. The question one must ask is how many resources should be spent on a science project that nets the same revenue as a traditional metal coating application. Exotic coating needs to be driven by the material supplier; the application and equipment suppliers can coat it if the material can produce the desired end user result.

The Biggest Unmet Needs in Powder Application Technology Today

Depending on who you talk to, opinions on where powder application technology needs remain unmet can vary widely. Some feel that First Pass Transfer Efficiency (FPTE) requires additional attention as less overspray means less clean-up, making any color change easier and faster to perform. Others believe that measuring the film build on parts before they enter the cure oven is a technology space ripe for advancement. Current models can tell what is being applied in a general range, but there is no onthe-fly adjustment to the application equipment. Technology that allows accurate reading of pre-cure parts to compare to specification for final cure as well as a feedback loop that then makes changes to the appropriate application devices to correct deviations real time would provide more efficient powder use and a significant reduction of reject and/or rework parts.

It’s no surprise that a march toward achieving Industry 4.0 is evident on a number of fronts. Improvements will continue to be made in material handling, allowing for better control and management of the powder while spraying and cleaning. This includes incorporating automation controls linking machines together and enhanced communication and data sharing for the emerging trends associated with Industry 4.0.

Integral to Industry 4.0 is the gathering and using of information that allows for remote information collection which avails intervention. Currently, apps exist to monitor the equipment, but the ability to make remote adjustments —e.g. if KV is low or flow rates are off set points—is only available on a limited basis. Some manufacturers recently introduced this function. Question also remains in terms of information overload. Asking for information is easy but doing something with the output is often not achieved.

industry-linking-machine

Industry 4.0 improvements continue to be made by linking machines together through automation controls and improved communication and data sharing.

Not all unmet needs in the industry are tied to technological advancements. A somewhat obvious, less technical challenge is the importance of ground for successful powder coating. Often overlooked if not completely ignored in the field, we need to find a way to quantify the cost of bad ground. Until that is done, investments required for improving ground path will not happen.

Another ongoing issue in the industry is education. We could have the best technology in the world, but it is useless without a skilled workforce that understands it and knows how to operate it at an appropriate level. Simply stated, we need to find a better way to communicate and deliver training. There seems to be a lot of turnover when it comes to painters and too often training of new painters consists of handing them a gun and telling them to spray the part.

Opportunities for Growth

Interestingly, one of the most prevalent growth areas in the powder coating industry continues to be the traditional conversions from old paint technology to powder. Liquid to powder conversions are still happening and each of these conversions is a great opportunity for growth within the powder market. Hands down, powder coatings are the best solution for companies looking for “green” coating solutions. Any company that is considering a conversion to waterborne coatings as a finish solution should strongly consider converting to powder coatings. The economic, environmental, and performance advantages make powder coatings an excellent choice.

Service, training and technology may be the next growth areas in the powder industry according to some experts. With unemployment in the U.S. at historic lows, the employable workforce has jobs and they have options to jump to other jobs. Turnover creates an endless need for suppliers to provide constant training and service packages to keep equipment running. In some cases, technology has to fill the gap when there aren’t employees to maintain the finishing line. Therefore, the need for robotics and intuitive equipment that pushes information to management in real time between failures continues to grow.

Forecasting the Future

Gazing into the crystal ball, powder application experts appear to see evolution rather than revolution. Most are working on technology that addresses the challenges above and approaching markets that make sense for powder without tying up resources chasing science projects. The focus is on products that we believe will lead the industry in technological advancements and application performance which are demanding process solutions that spray less powder, create fewer rejects, use less labor, and increase productivity.

It is clear that innovation is alive and well in the powder coating application technology sphere. The engineering stalwarts in the industry are busy working away at incremental advances in part visibility, powder pump design, improved electrostatic control and real time, remote feedback loops. The industry is in good hands with the strong commitment of spray equipment designers and manufacturers.

Contributors

Gema USA Inc.
www.gemapowdercoating.com

Nordson Corporation
www.nordson.com/powder

Parker Ionics
www.parkerionics.com

Sames Kremlin Inc.
www.sames-kremlin.com

Kevin Biller is technical editor of Powder Coated Tough and president of The Powder Coating Research Group. He can be reached at kevinbiller@yahoo.com.

Author: PCT Editor