Despite the rise of digital printing, flexography still accounts for some 90% of printed labels in the market today. The anilox roll functions in much the same way as the engine propels an automobile. And if the anilox roll is dirty, it is a virtual impossibility to produce a crisp image.
“If the anilox roll is the heart of the flexo printing process and critical to maintaining a well-run operation, then proper cleaning, care and maintenance of your anilox inventory is essential to your survival,” explains Ryan Potter, VP of sales at Flexo Wash US. “The absence of good cleaning practices always will lead to inconsistent print results and increased downtime.”
If the anilox cannot carry the specified volume of ink to create the desired ink film thickness, many variables will be affected. “Whether its brand color matching, ink densities, print quality or even press speeds, the anilox can affect one or all of these variables due to ineffective cleaning practices,” says Peter Mulheran, sales manager at Eaglewood Technologies. “Conversely, if the anilox is dirty and remains dirty, there are operator workarounds that are detrimental to the anilox and/or the printing press.
“It’s always much more cost effective and prudent to be proactive rather than reactive when it comes to anilox maintenance,” he adds.
Shortcuts can ultimately prove detrimental. Increasing blade pressure on the anilox can return some color matching or density improvements but only by sacrificing the surface of the anilox. This practice wears out the anilox prematurely, increases the potential for scoring lines and puts undue stress on the anilox.
Sonic Solutions provides ultrasonic cleaning systems for anilox rolls and sleeves, which are available from 6" to more than 10 feet. “The cleaning process consists of two steps,” explains Joe Walczak, president, Sonic Solutions. “The first is soaking the roll to allow the chemical solution to soften the inks and resins that are dried within the cells of the anilox. The second step is to apply the ultrasonics to gently vacuum the contents out of the cells. It is quite an efficient process that can remove 100% of the dirt within the cells, even the tiniest of crevices in the pours of the ceramics.”
Bill Warner, vice president of Allison Systems, says that anilox cleaning is a commonly neglected practice. In addition, many anilox rolls are often sent out for reconditioning, when all they need is to be cleaned.
“When neglected, the process is more tedious and can often require other methods of cleaning that utilize specialized equipment to achieve the desired results,” says Warner.
A roll that has not been maintained will have the effects of being “plugged,” where the cells of the roller are blocked with ink. The roller will subsequently fail to transfer ink to its intended surface. “This ‘plugging’ can also leave tiny pinhole-sized holes on the finished label,” notes Rick Principato, president and CEO at Tower Products. “In the case of photopolymer plates, if the plate is not properly cleaned, this will drastically affect the image quality of a label, as new ink may not be able to adhere properly to the image area. Even worse, the plate itself may end up totally unusable if ink has been left on it for too long.
“When it comes to cleaning anilox rolls, it’s all about unplugging and removing ink and debris buildup in the roller cells,” says Principato. “The rolls are covered in ink while in use, and ink within the cells can dry very quickly due to how tiny the cells are, so removing it quickly is paramount.”
Dirty anilox rolls will lead to inconsistent print quality, increased downtime and excessive waste–nothing particularly advantageous for a label converter.
“Converters cannot wait on cleaning their rolls until the anilox cannot perform anymore,” adds Potter, whose company currently has over 20 anilox cleaners on the market. “The market is too competitive. Plugged and dirty anilox rolls create surface tension, which prevent cells from accepting and releasing the correct ink volume. This, in turn, always results in bad print quality. You must have a clean anilox roll to have a quality print job.”
There are other downsides to dirty anilox rolls, too. “Each time the operator stops the press, it sits idle and more ink and paper are wasted, as well as the operator’s time. Should the operator not catch the problem and the print job goes to the customer, they may just reject the entire order or go to another printer entirely,” says Walczak.
The anilox cleaning process has improved, much like many other facets of the labels and package printing industry. “Features, such as the traceability program, allow for the entire anilox inventory to be seamlessly tracked and monitored throughout their life cycles,” states Mulheran. “Our Sitexco System provides significant cleaning improvements, and microscopes can be easily connected to the PC touchscreen for roll analysis and auditing. The Sitexco System does not require mixing or disposal of any chemicals, media or consumables of any kind.”
The anilox cleaning process can vary from company to company. For Eaglewood, the anilox is placed inside the machine, and the operator then selects which anilox needs deep cleaning, and turns it on. “Every cylinder will leave the machine perfectly clean, every time,” adds Mulheran, whose company offers the Sanilox roll cleaning system, as well. “This translates into improved color matching, improved densities, improved print quality, reduced down-time, reduced ink and substrate waste, and a more sustainable method for cleaning.”
Flexo Wash, for example, offers two solutions: The Liquid Anilox Cleaner and the Laser Anilox Cleaner. For the Liquid Anilox Cleaner, the automated cleaning process involves a low pressure spraying of the roll with a cleaning solution, followed by a high-pressure water rinse and an air blow dry to finish. For the Laser Anilox Cleaner, the cleaning is done through the process of ablation. The high-frequency laser cleans the anilox with a precisely-defined pulse, which ensures an even distribution of energy.
“Flexo Wash offers environmentally-friendly cleaning solutions for all our cleaning systems. The liquids are recirculated, minimizing their use and lowering your costs,” says Potter. “The laser, on the other hand, evaporates the ink, then an extraction system removes the leftover particles, dust and fumes. The cleaning program automatically stops when all the extraction processes are finalized.”
Warner adds that it is best to clean anilox rolls soon after being removed from the press. “The liquid cleaning products we provide are manually applied to the anilox roll using either the Erazor sponge or a cleaning brush. When using these products, remember that a little product goes a long way,” he notes. “Using more product is usually not necessary or beneficial. The product is applied to the surface of the roll in a circular motion, and then the dissolved ink can be removed from the anilox with Press Cleen wipes or a lint free cloth. When all the ink is removed, the roll is rinsed with clean water. After rinsing, it is very important to dry the anilox roll to avoid water stains.”
This is not a simple process, either. “Today’s inks and coatings can be difficult to clean, even when they are still wet,” says Potter. “The longer an ink or coating has been allowed to dry in the cells, the more difficult the cleaning process can be.”
Advancements in cleaning
Modern anilox rolls feature thinner cell walls, higher line screens and can accommodate tougher inks. Not all anilox cleaning methods are created equally, either. The technology has advanced considerably in recent years, with suppliers fine-tuning their products to enhance the flexo printing process.
“Flexo Wash’s cleaning technology has adapted to modern advancements. We use a safe and gentle cleaning method that does not damage even the thinnest of cell walls,” explains Potter. “In fact, the cleaning method offered by Flexo Wash means that you can both deep clean the rolls and wash them on a daily basis without harming even the highest line screens. It does not matter if the anilox is wet or dry. It does not matter if you need to clean water-based, solvent and/or UV inks, adhesives, lacquers, varnishes, laminates, etc. We can clean them all.”
The anilox cleaning process has evolved to meet the demands of today’s label converters. Automation, specifically, has helped anilox cleaning suppliers meet converters’ timeline for quick turnaround times and inline cleaning.
“Anilox cleaning technologies have changed significantly in the recent years,” says Eaglewood’s Mulheran. “While laser has been around for about 10 years now, it is now becoming widely accepted as the preferred anilox cleaning method. Days of scrubbing aniloxes by hand with a brush and surfactant are no longer.”
Mulheran adds that the Sitexco laser system makes the process repeatable, sustainable and simple. “The machine can clean, measure, track and control the most important variable in the flexographic print process,” he says. “It’s not just cleaning anymore, it’s inventory management.”
Wash and blasting systems have been around for some time, and Sonic Solutions’ Walczak says the technologies “have become quite archaic.” The evolution of ultrasonics has made the cleaning process that much more efficient. “This technology has evolved to increase the level of ultrasonics to be even safer for the highest line count rolls,” he says. “Laser cleaning is quite new and very expensive – over $100,000 – and the long-term effect on the anilox rolls is still not understood.”
Walczak adds that ultrasonic anilox cleaning is “really quite a hands-off operation.”
When it comes to the anilox roll, time is money. “Cleaning has certainly become a lot less time-consuming in recent years due to the emergence of automated photopolymer and anilox cleaning machines,” says Tower Products’ Principato. “Tower has gained its reputation in this area by developing machine-compatible chemistries. Washes like our Smartflex UV Flexo Cleaner and Smartflex Flexo Wash Plus were designed specifically for this purpose. The key to a great cleaning process is to use products specifically designed for our industry.”
According to Flexo Wash’s Potter, this is not your father’s anilox cleaning process. “With both our liquid and laser cleaners, we have the capacity to clean everything a converter has,” he says. “Both cleaners are fully-automatic, quick, safe and effective, so the cleaning process on-site is very seamless. All of our machines employ a ‘plug n’ play simplicity,’ which means the employee just needs to put in the dirty anilox rolls and hit start. The cleaning process is all done by machine now.”
The anilox roll
Anilox cleaning products, of course, only work with the anilox roll. Harper Corporation of America has manufactured and restored rolls with enhanced properties, including better surface transfer, greater volume transfer, higher line screen precision, more consistency and faster speeds.
Harper has developed solutions that range from anilox rolls to cleaning products, all designed to improve the flexo printing process. “Harper is always researching. We have a number of new engravings we offer, but we tailor to the customer’s needs along the lines of speed, transfer, substrates and ink properties,” explains Sean Teufler, technical director at Harper. “In regards to cleaning, we have developed a number of new cleaners, like Performance Wash for external autowash systems and Anilox Surface Cleaner for removing stains that may occur from other cleaners a customer may use.”
According to Teufler, anilox technology has evolved with precision through niche engravings, polishing techniques and porosity reduction. The anilox is designed to serve ink and plate needs, so it is essential to generate the proper interaction to get the correct color, printability and sustained clean print results.
The anilox roll, the cleaning solution, and the position of the anilox will all play important factors. “If this is a shutdown process in a press deck, then the anilox should stay wet with ink until ready to clean,” says Teufler. “From there, be sure to use cleaners that break down the inks, not shock them into the cells. After a little scrubbing and a rinse with the appropriate liquid, the anilox surface should be ready for drying.”
Harper will also work with customers to design products that fit their working environment. “We always begin by asking how can we help and what kind of issues they are having,” he adds. “We make what we call ‘press-area’ audits and assess the customer capability in cleaning, storage and use. From there, we recommend a number of possible improvements.”
Much like a printing press can be tailored to a label converter’s needs, anilox rolls and cleaning solutions can be optimized for a company’s unique needs, as well.
“We like to get a full picture of a how an individual company’s pressroom works,” explains Tower Products’ Principato. “This means physically looking at what kind of press, inks and existing cleaning equipment (if any) are present. The most important aspect of this, of course, is the ink. Although many like to believe a ‘one chemical cleans all’ exists, the reality is that multiple types of ink require multiple types of cleaners. Tower will work with a client to ensure the best fit, even customizing a product if needed.”
“The products and methods used for anilox cleaning vary by type of ink system used, engraving specs, and anilox roll size to name a few,” says Allison Systems’ Warner. “Each printer has, or should have, a program in place for anilox roll cleaning and maintenance. Allison Systems works with the printer to see how the products we offer fit into their existing cleaning procedures, as well as offering suggestions for products to try to improve their cleaning efficiency.”
Flexo Wash, meanwhile, offers a range of cleaning solutions that extend beyond the anilox roll. The technologies are easy to use, and are often designed to meet the customer’s specific requirements. “Flexo Wash offers cleaning systems for every need, all of which incorporate our ‘Leading Cleaning Technology.’ We have many options for cleaning not just anilox rolls, but plates, parts, rotary screens and many other components,” says Potter. “All of our systems are user-friendly and operate with touchscreen automated technology. Our sales team can customize a system that best suits any converter’s needs, helping our customers print better.”
After some key questions are answered, suppliers can implement a program to best suit their customers’ needs. “Most of our customers implement a procedure where all aniloxes are put on a strict cleaning schedule,” states Eaglewood’s Mulheran. “Every anilox has an ID–such as a serial number, RFID chip, bar code–that allows it to be tracked throughout its life cycle. This ID allows the machine operator to locate and track every time it has been cleaned, who cleaned it, how it was cleaned, and the after-cleaning volume of each cleaning directly from the touch screen interface on our Sitexco System. This provides seamless tracking of all aniloxes.”
A customer’s information can be accessed by production members from their desktops via internet access. This data streamlines setup times on the press, translating into hours of savings at the end of each month. “This in turn reduces costs and goes right to the bottom line,” adds Mulheran.