A properly functioning anilox roll is critical to producing stunning flexographic labels. The anilox roll is only one part of the equation, though. A clean anilox roll can make the difference between award-winning labels or costly reprints and
customer dissatisfaction.

The downside of improper anilox maintenance is significant. The anilox is often considered “the heart of the flexographic printing press” due to its direct relationship with color matching, print quality, and, ultimately, press uptime. 

“Dirty aniloxes will have a negative effect on repeatability, quality and longevity of the anilox itself,” states Peter Mulheran, president, Eaglewood Technologies. “It cannot be understated how impactful improper maintenance of an anilox will be to anyone’s print process. Not only does a stringent daily cleaning process need to be adhered to, but aniloxes should be thoroughly monitored for efficacy before problems are manifested on-press. Being able to identify when an anilox is dirty, damaged or not capable of laying down the proper ink film thickness is paramount for reducing downtime and costs.”

There are countless failures when the anilox is compromised, too. “A dirty anilox roll will have a decreased BCM volume and cause inconsistency in overall printed colors,” says Al Husti, account manager, Anderson & Vreeland.

“Compromised cells contribute to reduced cell volume and can cause an uneven appearance, or unwanted patterns to appear in the final print,” adds Stuart Mitchell, director OEM and global sales support, Sandon Global. “With the industry increasingly focused on fast turnarounds and greater volumes, this can be disastrous for productivity.”

All Printing Resources (APR) even has a phrase for when dirty aniloxes fail. “Keeping aniloxes clean is crucial to avoiding press downtime caused by ‘chasing color’,” comments Joe Settanni, director of strategic initiatives/technical representative, APR. “When the anilox is not clean, it fails to carry and release consistent and expected amounts of ink. This inconsistency can lead to an increased potential for job rejections, both internally and by the customer, significantly impacting the printer’s reputation. Moreover, it may necessitate hand scrubbing aniloxes with caustic chemicals and brushes.”

Converters would be well advised to clean their anilox rolls before they’re dirty – or they think they’re dirty. The slightest imperfection could lead to dirty print.

“Converters cannot wait on cleaning their rolls until the anilox cannot perform anymore,” states Patrick Potter, president, Flexo Wash US. “The market is too competitive and dirty anilox rolls cause inconsistent print quality, increased downtime, excessive waste, and thereby loss of competitiveness. Also, a plugged and dirty anilox creates surface tension, which prevents 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.”

Cleaning methods have improved throughout the years, as well. What was effective 20 years ago would pale in comparison to the technologies of today. “Anilox cleaning methods have certainly evolved over the years,” says Paul Teachout, technical marketing specialist, Harper Corporation of America. “From traditional hand cleaners utilizing stainless steel brushes to the more recent laser cleaning systems, they are all very effective when applied to the proper application. They can also destroy a roller if not utilized to the manufacturer’s suggested operating procedures.

Anilox cleaning innovation must occur in tandem with other areas of the flexo industry. “Ink technologies are continuously improving, along with printing presses,” states Mark Principato, international sales manager and flexographic and technical development specialist, Tower Products. “The challenges are staying ahead of the inks and figuring out the best chemical formulations to remove them without harming the rolls.”

Like other print technologies, anilox cleaning has seen a fair amount of technological trends over recent years. The advancement of laser cleaning fits the bill. “Over time, these laser systems have evolved to become safer for the ceramic material, causing minimal laser damage to the rolls,” says Settanni.

The construction of the anilox roll is also vital. “We at Sandon are committed to robust quality control processes that enable us to create coatings durable enough to withstand chemical attack during cleaning,” says Mitchell. “In particular, lower porosity coatings are better protected against chemical attack in conjunction with a sealant such as Sandon Global’s enhanced densification treatment (EDT). With a harder coating, this risk is minimized, greatly reducing or even eliminating issues that can be encountered during the cleaning process. Porosity level tolerance of 1-2% and a hardness value of 1,300 Vickers are recommended for optimal performance against corrosion, general wear and tear, and scoring.”

Like other aspects of the industry, automation has its say in anilox cleaning, too. “Automation has provided new levels of efficiency as now rollers can be moved to the units and cleaned while operators pursue other activities,” remarks Teachout. “Hand cleaners are still widely used for on-press cleaning, but the automated cleaning systems provide the deep cleaning that the rollers require on a regular scheduled PM cycle to continue to meet graphic requirements on-press. Regardless if its manual, media blast, chemical or laser, all technologies have improved over the years, providing safe and effective cleaning options for all applications.”

Choosing a cleaning method

There are many factors for label converters to keep in mind when selecting a cleaning process for their anilox rolls, whether it be liquid, laser, or ultrasonic.

“Anilox rollers come in all shapes and sizes, they can be constructed of mild steel or aluminum bases,” explains Harper’s Teachout. “The construction of the base materials must be considered when identifying the proper cleaning methods. Aggressive chemical cleaners can attack these base materials, causing corrosion that can then affect the ceramic coating. Here at Harper we offer the lowest levels of ceramic porosity in the industry to alleviate this concern. Ink chemistry can vary from high PH water based, solvent or UV, and all require different cleaning methods to break down or dissolve inks. These different chemistries will have a major influence in your decision process.”

Anderson & Vreeland’s Husti summarizes the industry’s offerings. “Ultrasonic cleaning technology is highly effective, economical, and has a minimal investment cost,” says Husti. “Ultrasonic technology has evolved and can even include dual frequencies and adjustable power. Laser is the newest cleaning technology that uses no chemicals, making it environmentally friendly. It’s a fast, high quality, effective method, which can substantially reduce cleaning times.”

“Don’t overlook ultrasonic cleaning as inferior to other technologies,” adds Joe Walczak, president, Sonic Solutions. “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 and keep it simple.  You’ll really save time and money in the short and long run.”

Flexo Wash, for example, offers liquid and laser cleaning. According to Flexo Wash’s Potter, laser cleaning delivers a deep cleaning and is fully-automatic. The laser cleaning process does not generate any waste and does not require a water source. Plus, there is no need for adaptors or gear covers, and it is highly effective on difficult inks. Automatic sleeve identification (RFID) is possible, as well.

“Companies that would most benefit from the laser cleaner have three qualifiers,” notes Potter. “First, they clean less than 30 rolls per day. Next, they have a large inventory for each type of anilox. Lastly, they leave their anilox in the press longer, with fewer changeovers.”

Eaglewood Technologies’ Mulheran touts investigation in this arena. There are various technologies available and one technology will not fit every need. “Be mindful of those companies pushing only one technology,” remarks Mulheran. “Variables such as quantities of aniloxes, frequencies in cleanings, ink/coating/varnish chemistries and anilox specifications should all be considered when looking for the correct cleaning technology.”

Anilox cleaning has evolved significantly over the last 10 years. According to Mulheran, this is primarily due to the market acceptance of laser anilox cleaning. “Laser anilox cleaning has offered the market an environmentally safe technology that can also improve the print process,” he says. “Additionally, the right laser anilox cleaning system can manage the inventory, help identify when issues are present, reduce the reliance on personnel to make those decisions and make the management of large anilox inventories seamless. Laser anilox cleaning is safe to the aniloxes, safe for the environment, and safe for the operators.”

Ultrasonic technology uses sound waves to break up hardened ink. “Ultrasonic systems have really evolved to become a great way to clean anilox rolls,” notes Walczak. “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 vacuum the dirt off the anilox. It’s really a great way to thoroughly clean off the anilox. Ultrasonics is a proven technology that is used in numerous industries where precise cleaning is needed and required. Hospital operating rooms use them to clean various apparatus, as well as NASA and the space industry.”

There are other methods, too, comments Sandon’s Mitchell. “For example, manual cleaning using liquid-based chemicals and brushes is often effective but can be time-consuming,” he says. “Power washing is another method that can again involve aggressive use of a high pH caustic cleaning solution, which can lead to surface corrosion.”

There are a host of reasons to choose one method over another. Damage to equipment can be one. Safety is another. “Cleaning consideration should be made to not damage the roll,” explains Anderson & Vreeland’s Husti. “The equipment should be reliable, easy to operate, efficient, and cost effective. Not making the right decision or utilizing the right cleaning method can be expensive from a labor, ink, production, and material waste standpoint.”

APR stresses the importance of safety associated with the laser cleaning process. “Safety and productivity are at the forefront,” adds Settanni. “Adopting laser cleaning technology eliminates the need for caustic chemicals, which are used as an alternative to lasers. Laser technologies ultimately provide a safer alternative for operators. Safety also involves choosing cleaning systems that do not damage the anilox itself. Another important consideration is the potential to prolong the life of the anilox roll. By extending the anilox’s lifespan, printers can reduce expenses associated with replacing aniloxes.”

Conversely, liquid cleaning is a fast cleaning process of 10-20 minutes. Daily deep cleaning is possible, and there is no wear and tear on aniloxes. This method is also easy to operate. “Companies that would most benefit from liquid cleaners have several qualifiers,” adds 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. They have a need for deep daily cleaning, and they need to clean multiple aniloxes in 10-20 minutes. Lastly, they want a lower upfront capital expense.”

“The primary advantage of liquid cleaners is the ability to attack and remove ink deposits from the cells, totally and effectively,” adds 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.”

As brands increasingly demand shorter runs, ultrasonic cleaning becomes more advantageous. “Shorter print runs go very well with our cleaning systems,” says Walczak. “More and more of our customers are making it a priority to clean their anilox rolls and sleeves after every press run.  This assures them that every time they use that anilox, the color densities come out great.”

Due diligence is the name of the game when selecting an anilox cleaning method.

“Laser cleaning is not laser cleaning,” says Mulheran. “There are many players in the market, and everyone does it differently. Investigate, get references, conduct cleaning trials, and rely on those who have lots of experience in this space.”

A sustainable process

Anilox roll cleaning need not be a wasteful and environmentally harsh process. In fact, suppliers have prioritized technologies that deliver increased sustainability. “Effective anilox cleaning technology contributes to sustainability by minimizing the usage of ink and substrate,” explains APR’s Settanni. “A thoroughly cleaned anilox ensures consistent and repeatable results. This predictability significantly reduces the amount of ink and wasted substrate that would otherwise end up in landfills. Properly maintained anilox rolls also extend their lifespan, resulting in fewer old rolls being discarded.”

The resources utilized in the anilox cleaning process can go a long way toward impacting a label printing business’ carbon footprint. “Businesses across the board are seeing more demand for sustainability,” says Flexo Wash’s Potter. “For our industry, we recommend that printers start evaluating their cleaning processes as the first step. With Flexo Wash, you can choose the best and most environmentally friendly solution for your operation. 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.

Flexo Wash has designed a Recirculation System to elevate anilox cleaning to an even more sustainable solution. By reusing the rinse water in the cleaning cycle, converters can achieve approximately 75 washes from a tank of nearly 50 gallons of water.

Do you keep your rolls clean?

It makes no difference whether you are running a fleet of narrow-web flexo presses with open ink trays or big central impression cylinder machines with pressurized ink supplies and steps leading to the top of the press. They still have one thing in common: anilox rolls.

Provident’s ink systems experts recommend cleaning rolls after every shift and certainly after long-run jobs. This doesn’t mean a casual wipe with a dirty rag, something we see all too often, especially on smaller presses. Wiping with a cloth picks up the ink that remains on the surface of a roll but does little for the cells, except help ensure ink can be left in the cells to dry, making the roll a bit less efficient after each job.

We know it takes time to remove a roll and perform a thorough cleaning in a tank dedicated to the purpose, so this process is best left to the end of a shift or during weekly scheduled maintenance. However, using a clean rag and the appropriate cleaning solution between jobs can keep a roll in better condition and help guard against declining print quality.

We offer a full suite of tailored cleaning products that are safe for cleaning water-based, solvent, and UV inks and coatings. Customers can rely on Provident’s solutions to help them perform at their best.
• Designed to reduce ink build-up, minimize waste, and speed up removal so you can run more efficiently.
• With cleaner press room operations comes crisper, more efficient prints. Traditional cleaning techniques leave build-up behind; our system helps you deliver clean consistency.
• Prevent waste, and wear and tear with daily maintenance.
• Environmentally safe.

As the market leader in professional flexo cleaning, you can trust in the quality and performance of Provident’s selection of anilox cleaning products. Contact us today to find out more www.providentblades.com

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