A properly cleaned anilox roll will lead to higher output on a flexographic press while simultaneously reducing downtime, material usage and labor costs. However, when looking for the weak link in production, anilox cleaning might not be the first culprit printers point to. And even when a dirty anilox is properly identified, converters must overcome the challenge of truly getting the anilox clean.

The last two years have only exacerbated the need for enhanced cleaning technologies. Workforce challenges – associated with the pandemic or not – and supply chain issues have emphasized pressroom efficiency, especially since converters cannot afford the costs associated with rejected prints.

Speed and quality, of course, are still paramount. “Since the pandemic, the printing industry experienced massive surges in demand and production needs, all with major labor shortages,” notes Patrick Potter, president, Flexo Wash. “As the printing industry modernizes and the production demand increases, the cleaning process needs to modernize as well. There comes a point where so much money is lost by the printer if their cleaning systems are not up to par. Downtime, ineffective manual cleaning or poorly automated cleaning systems all take a heavy toll on a printer. A fully-automatic cleaning system is part and parcel of a successful printing operation. Printers either realize this immediately or it becomes a big pain point in their process.”

There are questions that converters should ask when looking into cleaning methods, says Mark Principato, director of flexographic products and international sales, Tower Products. The first question should target the types of inks being utilized and if the converter has previously had difficulty removing those inks from the anilox roll. “You also have to assess whether you have the right equipment to perform these tasks, too,” he notes. “Ink technologies are continuously improving along with the presses. The challenges are staying ahead of the inks and figuring out the best chemical formulations to remove them without harming the rolls.”

As with a press or finishing solution, it is critical for converters to use anilox cleaning products that are tailored to their individual needs. While one product or method might work well for one converter, an entirely different setup would suit another. For example, liquid anilox cleaning might work for one label printer, while laser would be optimal for a different company.

“There is no cleaning solution that fits every need,” explains Peter Mulheran, vice president and general manager, Eaglewood Technologies. “We believe in understanding the current and future needs of our prospective customers to better understand which technology is best for them. Whether it’s a sustainability initiative, a desire for better control over their anilox inventory, or they’re looking to simply upgrade a legacy asset, Eaglewood truly has the best available technologies.”

There are three methods converters will face when selecting a system: liquid, laser and ultrasonic. With the liquid methods, converters utilize a cleaning solution or some other particle, like sodium bicarbonate, and immerse it under high pressure against the roll.  Think of a power washer, as an example. The laser cleaners essentially burn away the dirt and debris off the roll. At these high temperatures, the contaminates are basically evaporated off and turned into dust. These systems are the most expensive in the marketplace and have a good niche with the largest of anilox rolls – typically seven feet or longer.

“Ultrasonic systems have really evolved to become a great way to clean anilox rolls,” states Joe Walczak, president, Sonic Solutions. “With this method, the cleaning solution used works to soften the debris in the cells of the anilox, and then the ultrasonics gently and safely vacuums the dirt off the roll. It’s really a great way to thoroughly clean off the anilox.”

The newest ink technologies have not simplified the task, either. In fact, challenges present themselves even when the inks are still wet.

Paper Converting Machine Company (PCMC), a Barry-Wehmiller Company, offers the Laser Meridian Elite and has customers successfully cleaning anilox rollers utilizing water-based inks, solvent-based inks, UV inks and coatings without difficulty. “As a standard feature, we offer four options for roll cleaning duration, such as light, medium, heavy,  or maximum, based upon anilox engraving type, anilox cell geometry (lpi, bcm), ink pigments, and frequency of roll cleaning,” states Rich Stratz, strategic accounts and Western States sales manager, PCMC.

“Today’s inks and coatings can be difficult to clean, even when they are still wet,” adds Potter. “The longer an ink or coating has been allowed to dry in the cells, the more difficult the cleaning process can be.”

Not only are new ink technologies requiring more scrutinized anilox tolerances, but new press technologies and brand owner demands are challenges, as well. “Flexography is evolving at an incredible pace, so all things anilox are more important now than ever,” says Mulheran. “A properly cleaned anilox will not only provide impressive print results but will stay cleaner longer while reducing ink waste. Reducing ink waste is crucial to many flexographers due to current supply chain issues.  Anything that can reduce setup times, adjustments and waste will ultimately save time and, most importantly, money.”

According to Mulheran, one of the biggest challenges in the label industry, especially as it relates to anilox cleaning, goes beyond the equipment and supplies. Therefore, optimizing the equipment – with simplicity in mind – will be critical for the future of print.

“The largest issue we see regarding the changing nature of printing is the people problem,” he states. “In many cases, the newest and greenest employees are being tasked in maintaining aniloxes. This can be problematic without the proper training and knowledge of how critical the anilox is to the flexo process. An anilox cleaning system that can clean aniloxes perfectly with a touch of a button is essential and also one that can track every anilox in inventory. This will help alleviate press constraints and free up time for pressroom personnel to focus on getting quality product out the door.  Yes, short press runs are requiring more from the press operators, but to us the people puzzle is impacting our industry more than anything.”

When dealing with issues related to production, it is quite helpful to automate one’s converting processes. This has become a staple throughout the pressroom, and anilox cleaning is no exception. PCMC has added Accelerate to its arsenal. This Industry 4.0 solution has been optimized for anilox roll cleaning reporting and to provide remote alerts to the operator regarding roll cleaning status. Optionally, PCMC offers a bar code scanner or RFID Pen Reader to simplify the start-up sequence for anilox roll cleaning and to aid roll cleaning reporting.

Due to these developments, PCMC has promoted a safe and efficient anilox cleaning process with its Laser Meridian Elite technology.

Method selection

When deciding among liquid, laser or ultrasonic anilox cleaning methods, converters must consider a range of pros and cons. Liquid anilox cleaning allows for fast cleaning, often in 10-20 minutes, and does not produce any wear and tear on the anilox rolls. Liquid systems are easy to operate and allow for daily deep cleanings.

“Companies that would most benefit from liquid cleaners have these qualifiers,” explains Flexo Wash’s Potter. “First, they clean more than 30 rolls a day. Next, they have a limited inventory for each anilox. They have a tight production schedule with multiple changeovers per day, and they have a need for deep daily cleaning. They need to clean multiple aniloxes in 10-20 minutes. Lastly, they want a lower upfront capital expense.”

“The main advantage of liquid cleaners is the ability to attack and remove ink deposits from the cells totally and effectively,” comments Tower Products’ Principato. “Most automatic cleaning units have an ultrasonic component built in, along with a high-pressure spray, which will always result in a clean roll when done on a proper maintenance schedule.”

Laser anilox cleaners also enable daily deep cleaning without the need for a water source. Highly effective on difficult inks, laser cleaning is fully automatic and does not generate any waste.
“Companies that would most benefit from the laser cleaner have three qualifiers. First, they clean less than 30 rolls per day,” adds Potter. “Next, they have a large inventory for each type of anilox. Lastly, they leave their anilox in the press longer, with fewer changeovers.”

“Converters need to understand how the manufacturer is applying the energy from the laser to the surface of the anilox, and is it truly in a safe manner to protect the anilox’s surface,” adds PCMC’s Stratz. “We spread the energy out over 150mm, plus we use 2/3 less energy at the ablation process than our previous design or competitors.”

Ultrasonic systems have really evolved, both inside the industry and out. “Ultrasonic cleaning is a proven technology that is used in numerous industries where precise cleaning is needed and required,” says Sonic Solutions’ Walczak. “Hospital operating rooms use them to clean various apparatuses, as well as NASA and the space industry. It’s a very simple but tremendously effective way to clean an anilox.”

Ultrasonic cleaning systems for anilox rolls will vary in cost depending upon the size of your rolls. They can range from under $10,000 for small 16″ anilox rolls to under $40,000 for a 72″ sleeve. “Don’t overlook ultrasonic cleaning as inferior to other technologies,” adds Walczak. “It’s a tremendously effective, efficient, thorough and safe method for cleaning anilox rolls and sleeves. Thousands of printers rely on our systems every day to keep their presses running and not sitting idle. Separate the marketing glitz from the true function of the equipment.”

Of course, deciding between each method is a collaborative process, one that involves an understanding of the unique needs of the customer. “It’s important to dive deep into understanding current cleaning requirements and future needs of each flexographic printer/converter,” says Eaglewood’s Mulheran. “Up-front costs, consumables, sustainability, usage, cleaning speeds, and throughput are all critical in understanding what is best for them. If a company only represents one type of technology, to us that’s a red flag. They may try and persuade a prospective customer into using something that isn’t an ideal fit.”

Sustainable endeavors

Although not the first process that comes to mind, using the right anilox cleaning technology can foster an improved carbon footprint. Now more than ever, brands and consumers are demanding more environmentally-friendly processes. Plus, improving one’s operations can also impact a printer’s bottom line.

“Sustainability initiatives must reduce environmental impact, cannot negatively affect profitability, and improve employee quality of life,” remarks Eaglewood’s Mulheran. “Anilox cleaning can reduce environmental impact, but can it also reduce costs and improve employee quality of life? Yes, to all of these. The right technology can accomplish all of these by eliminating water usage, reducing operating costs and providing process improvements.”

Businesses across the board are seeing more demands for environmental sustainability. “For our industry, we recommend that printers start evaluating their cleaning processes as the first step,” states Flexo Wash’s Potter. “In addition to new products and built-in upgrades, we have a line of environmental solutions that can be combined with the different Flexo Wash cleaning units to reduce the water and/or liquid consumption. All our products are continuously optimized to ensure better reuse and less consumption of both water and cleaning liquid.”

Additionally, Potter notes, an effective anilox cleaning system can reduce wasted ink, substrates and press run time during job setups by ensuring that the anilox is well maintained and always operating at optimal performance.

“The more often rolls are cleaned, the longer the rolls will last and their ability to hold ink extends tremendously,” says Tower Products’ Principato. “Because of this, the press room minimizes wasteful spending on constant resurfacing or totally replacing rolls.”

According to PCMC’s Stratz, laser anilox cleaning fits the bill for converters looking for a sustainable solution. “With laser cleaning you get a very green and sustainable solution, since you are not using any of the earth’s resources like water, chemicals and drains,” he says. “With a laser you simply have some ablated ink dust that is landfilled after about every 75th cleaning. The particles are less than five microns, too.”

New products

Suppliers have developed a wide range of technologies to meet every converter’s cleaning needs. Eaglewood Technologies, with a focus on continuous improvement, has optimized the Sitexco+ Laser Anilox Cleaning system. It has been designed to allow for enhanced cleaning capabilities, cleaning speeds and safety to the anilox. 

“Historically, laser anilox cleaning could subject the anilox to too much laser energy,” says Eaglewood’s Mulheran. “With the Sitexco+ technology, that is a thing of the past. The cell-by-cell cleaning capabilities of the Sitexco+ technology offer superior cleaning results with no long-term impact on the anilox cells, no matter the line screen.”

Meanwhile, Flexo Wash’s Laser Anilox Cleaner is safe, effective and environmentally friendly. Most recently, the company introduced its LaserX series, which guarantees cleaning in half the time, an advanced laser technology, and a high degree of safety.

“The LaserX series promises all the same high-quality cleaning but twice as fast,” comments Flexo Wash’s Potter. “This is an optimal choice for printers wanting to invest in new technology from a trusted company that has reduced cleaning time.”

PCMC has patented a rotary scanner design that offers customers smarter, safer and faster anilox cleaning. PCMC’s wider devices permit sequential cleaning of multiple anilox rollers via a single make-ready. Cleaning multiple rolls in a single pass is advantageous for printers with a large volume of anilox rollers for cleaning.“The PCMC Meridian Elite is one of the most cost-effective solutions available,” explains Stratz. “It only uses ½ kW hour of power every 20 minutes when cleaning. On average, our customers are done cleaning in 15-20 minutes.”

Sonic Solutions has seen its technology vastly improve in recent years. The company has adjusted its ultrasonic frequencies to 68 kHz from the industry standard of 32 kHz.  “Our modified power generators are now external to the cleaning system,” says Walczak. “This keeps these critical electronic components safer from the cleaning solutions and also becomes interchangeable. This means that if for some reason the system goes down, a temporary loaner generator can get you up and running again in a day instead of a month.”

Tower Products has targeted its newest solutions at the pressing needs of label converters across the globe. The company has optimized its Smartflex Anilox Cleaning Gel for the changing nature of print, as run sizes continue to shrink and demands for quick turnarounds increase. “This gel gives the press operator the ability to quickly and effectively clean rolls while minimizing down time,” explains Principato. “We offer new formulations, specifically in liquid washes like the High Tech Anilox cleaner, that have been formulated to attack all types of inks.”


The anilox’s role in the cleaning process
An innate understanding of the anilox is important for converters when selecting a cleaning method. Harper Corporation of America has the luxury of providing a nuanced view of the market, since the company offers both anilox rolls and anilox cleaning solutions.

Harper advises label printers to consider the construction of their anilox when analyzing cleaning methods. For example, cold steel bases and aluminum-cladded sleeves are the two main constructions – and they feature disparate requirements.  

“These metals all react differently to inks and cleaning solutions,” explains Bill Poulson, technical solutions manager, Harper. “Is the cleaning solution compatible with the ink or coating being used? This is a question you need to ask yourself before using any detergents or cleaning products. We have water-based and solvent-based cleaners.”

Off-line cleaning systems come with a host of manufacturer requirements, too. “If you are using anilox sleeves with ultrasonic cleaners or pressure-wash cleaners, make sure you have end caps that fit well on each end of the sleeves and they have a tight seal,” states Poulson. “Compressible sleeves should never be submerged or exposed to water. Make sure the exposed aluminum cladding does not come into contact with the cleaning solution either.”

When cleaning anilox rolls by hand, label converters are advised to use a chemistry that will not attack the construction of the roller. This is especially true with aluminum base rollers or sleeves with aluminum cladding. All rollers should also be rinsed well after cleaning to remove any residual cleaning solution that is left on the roller’s surface.

Harper’s technical solutions and sales teams work diligently with converters to promote an increased understanding of the anilox and how to best service them, which includes cleaning. According to Poulson, the changing nature of printing – with greater demand for shorter runs – has not created increased challenges for the Harper team. In fact, Harper’s network of experts has promoted anilox standardization throughout pressrooms.

“We do our best to educate pressrooms in this way,” comments Poulson. “Having a standardized inventory allows for the best color management. No matter how short or long a run, you will be able to match color on the first press pull. This allows for less time changing anilox rolls on make-ready and less material waste.”

But how does this standardization take place? This can be done by running a banded roller to standardize the line screens and volume to a converter’s polymer plates and ink being used. Next, the ink room needs to be tuned to the same volumes used on-press.  

“Using Harper’s QD Proofing System allows for that correlation to press anilox rollers,” emphasizes Poulson, adding “Once the ink room knows the target volumes needed for the work their pressroom produces, they can correlate those volumes on their QD Proofer to the press. The proofer can mirror the same engravings as the presses use. This minimizes waste and downtime on-press. Therefore, ink goes to press ready to use.”

For cleaning solutions, Harper’s Ceram Clean II and Solv-It work well on all inks. Combined with its X-Cel Stain Remover Pads, this represents the company’s most popular cleaning solution. Meanwhile, Harper’s AltraWash Systems are cleaners that can be diluted from 1:1 up to 7:1 with water depending on their use. AltraWash Green is an aluminum safe product, too. The more diluted formula can be used on polymer and rubber plates.

“Our Performance Wash is a cleaner for ultrasonic and pressure- wash systems,” adds Poulson. “This cleaner is blended 1:1 with water. Most importantly, take time to have our HTS representative come in and do cleaning seminars. They will help you solve any cleaning issue you may have.”

Throughout the years, Harper Corporation has also optimized its anilox roll technology, including both hardware and software. This has taken place, most notably, with the engraving process. One such product of that advance in technology is Harper’s new XCAT engraving.  

“In addition, we are constantly working to improve the durability and performance of our coating process,” says Poulson. “Our coatings are the most consistent in the industry, which provides us the capability to engrave line screens and volumes that were unachievable in the past.

“We have always been committed to quality control,” he adds. “ISO is the foundation of the consistency of our products’ performance, and that ISO mentality has not changed at Harper. Harper utilizes the most advanced and precise measurement equipment available to ensure that this quality continues.”