We like powder coating. These protective finishes don’t just look deep and rich; they are, flexible, tough, eco-friendly, and durable. The process of using an electrostatic charge ensures that powder coating covers every inch of an object. This stuff is made to last. So, what if we need to remove it?
By Mark Kouri, June 18, 2021
If you use powder coating to cover parts in your production environment, you are probably already employing one or more of the four methods described below to strip your cleaning hangers and racks to prevent the build-up of powder coating each time you complete a job.
The four main ways to remove powder coating are:
- Chemical strippers
- Burn-off ovens
- Abrasives blasting
- Laser ablation
Because of its adherence and durability, powder coating is widely utilized for automotive parts, construction equipment, offshore rigs, and many other applications; but when it comes to removing powder coating, the characteristics that make it such an excellent covering can make it tough to remove. Chemical stripping, burn-off in an oven, and abrasives media blasting are the most common ways of cutting through the thick coatings.
Chemical paint stripping is commonly used on the delicate skins of aircraft, but chemical stripping methods use caustic chemical solvents to do the dirty work. They cause the powder coating to swell, soften, and/or dissolve; at which point the coating will begin to fall off, or it may be washed off. Chemical stripping is relatively inexpensive and readily available, and it does a good job of evenly removing powder coating. But it has its downside. Chemical solvents can be dangerous to work with, harmful to the environment, and can easily burn the skin and eyes of anyone coming in contact with them. Traditional chemical strippers may contain methylene chloride, phenols, or other hazardous solvents that can burn skin and eyes within seconds of contact. Proper handling and PPE (personal protective equipment) are required, as is special handling of the hazardous waste created through this process. Both the stripper and the water used to rinse the cleaned parts are considered hazardous waste and must be disposed of properly. Containment, cleanup, and disposal can be a costly and time-consuming paperwork and logistics headache.
There is one other important consideration, which may easily be overlooked when choosing the chemical stripping method—it leaves no anchor profile. An anchor profile is the microscopic texture of the surface of the substrate which gives powder coating, paints, and adhesives something to grip. Chemical stripping cleans a surface smooth; so, unless a proper anchor profile was given to the substrate before the coating was removed, it may be necessary to roughen the cleaned surface before applying a new coating. This adds an extra necessary step into the process which must be taken into account.
Burn-off ovens expose the parts to be cleaned to high heat, typically between 1,000-1,200F. At these temperatures, powder coatings ignite and burn away from the substrate, leaving only ash. The process is simple. Just load the oven, turn it on, and waiting for the oven to complete its cycle. This may be just a few minutes, or it could take several hours to burn coatings to burn off. Because of space requirements, high-cost, and special power and venting considerations, burns-off ovens aren’t for DIYers; but they are standard in many production facilities due to their capacity to process many parts at once with relatively little pollution or hazardous waste.
Burn-off ovens may work well to process parts made from steel or other hard metals, but the high heat required to burn off powder coatings may damage or destroy aluminum components. In many cases, aluminum will soften at temperatures lower than what is required to remove the powder coating.
Burn-off ovens have other disadvantages too. The ovens aren’t cheap to purchase or operate, and they take up lots of space. Parts being cleaned are offline and unavailable during the burn-off process, so production lines may be disrupted while burning is underway. And like chemical stripping, the burn-off method does not leave an anchor profile.
Abrasives Media Blasting (a.k.a. sandblasting)
Abrasive blasting, commonly known as sandblasting, is a cleaning method that has been around since the 19th century. Patented in 1870 by American soldier and inventor Benjamin Chew Tilghman, this method uses compressed air to propel abrasives (aluminum oxide grit, glass beads, silica carbide grit, etc.) at high speed towards the surface of whatever is being stripped of powder coating.
The process can be slow and cumbersome for removing powder coating. It requires lots of equipment, including an air compressor, a dust collection system, containment, a steady supply of abrasives media, PPE for the operator, and lots of clean-up and disposal. Sandblasting is noisy and is known to cause hearing loss. But that’s not the worst problem.
Crystalline silicates have been used universally in industry and architecture for decades as abrasive media, but crystalline silica dust has been irrefutably linked to lung cancer and incurable silicosis. For this reason, sandblasting using media containing more than 1% silica has been banned in most countries. The United States is not among them. Although OSHA, the CDC, and the National Institute for Occupational Safety and Health (NIOSH) have all published guidelines and/or standards to protect workers from respirable crystalline silica exposure, the practice of using silica abrasives in the U.S. has not been banned outright.
OSHA rules are making the practice less and less viable. However, as long as free silica is present in sandblasting environments, this will remain a significant health and safety risk for operators and anyone else who may be exposed to silica dust.
Laser Ablation (a.k.a. Laser Blasting™)
The latest viable cleaning method being adopted to remove powder coating looks like a page out of science fiction. Laser ablation or photoablation is the process of removing material from a surface by irradiating it with laser light. Laser Photonics’ CleanTech™ is a disruptive technology that opens up new possibilities for removing powder coating, and much more. The process is clean and fast, and when integrated with Laser Photonics’ user-programmable C-Robot, cleaning can be accomplished right on the production line, eliminating downtime and additional steps, such as removing racks, and loading and unloading ovens.
Laser Blasting with CleanTech™ uses clean laser light to vaporize powder coatings, leaving clean, bare substrate below. CleanTech™ lasers are programmable and can do both roughing and finishing work. That includes applying the desired anchor profile.
The CleanTech™ Laser Cleaning Robot is the first commercially available collaborative, easily programmable, AI-capable Laser Cleaning system in the United States. It fits right into a production environment, and goes to work, paying for itself immediately by reducing downtime and eliminating time-consuming processes.
Not All Laser Systems are Created Equal
Laser Photonics leads the way in innovative industrial laser systems. We implement solid-state fiber lasers and introduced our proprietary autofocusing C-Optics, which dramatically increase efficiency and accuracy by reducing fall-off. They are designed to handle complex contours and varying focal distances unlike anything else on the market. Our competitors can’t offer this revolutionary function, yet our Made In America laser systems remain competitively priced and incredibly reliable.
About Laser Photonics Corporation
Laser Photonics is the leading industrial Brand in high-tech laser systems for laser marking, laser cutting, laser engraving, and other material processing applications. Our systems are currently and historically used by manufacturers in the automotive, aerospace, industrial, defense, electronic, semiconductor, flat panel, and medical industries around the world. The Laser Photonics Brand of products is associated with a number of worldwide licenses and patents for innovative and ‘unique to the industry’ laser products and technologies.
Laser Photonic’s brand history is associated with better throughput, higher quality, and low cost of ownership for each of our products. We are raising the standards and working toward making everyone’s life simpler through each laser application. The Brand has, for more than 2 decades, been the industry standard workhorse of laser subtractive material processing for such world-renowned companies such as Sony, NIKE, 3M, Delphi, NNSY-Norfolk Naval Shipyard, NASA, Cannon Air Force Base, Eaton Aerospace, GE, Caterpillar, Harley-Davidson, PPG, Eli Lilly, Smith & Nephew, Millipore, DuPont, Bosch, Gables Engineering, Champion Aerospace, Smith Aerospace, Metaldyne, Dupont and Heraeus. The present license holders are committed to continue the legendary performance of Laser Photonics Brand Equipment and provide award-winning support to its past, present, and future customers.