Clean anilox rolls are a must for flexographic printing.

By Tom Polischuk

It’s a job that Mr. Clean probably wouldn’t take on, but somebody’s got to do it! Cleaning anilox rolls on a regular basis is part of every printer’s routine—a critical requirement for reliable flexographic printing.

Even though anilox roll cleaning is a common requirement in flexo printing, problems still abound due to misapplication or lack of knowledge. To get an idea of some real-world problems (and solutions) in the industry, packagePRINTING contacted a number of companies that provide anilox roll cleaning solutions to see how they solved specific customer problems. They supplied the following examples.

Clogged up

Bill Poulson, northeast technical graphic advisor for Harper Corporation of America, reports: “I had an experience recently with a roll that was running an adhesive for a two-ply lamination. We received a call that the roll was worn down completely. The coat weight was nowhere near the target coat weight they needed. This particular roll was only a few months old. My sales manager and I rushed up there to evaluate the situation.

“At first glance I had to agree that the roll had worn out. The surface of the anilox was smooth with a slight discoloration in the ceramic. I brought along a lab microscope to diagnose the roll. With the microscope I could not find any cell formation at all. The surface of the roll felt like smooth ceramic.

“A small area on the roll was cleaned with our cleaning paste, Ceram Clean II, and I started to see some cell formation. After multiple cleanings in that area, the engraving was exposed and the roll had no wear characteristics at all. This roll needed a real good cleaning and it would be back in production. It took some effort to clean the extreme plugging on this roll, but the Ceram Clean II product worked well as it always has in the past.

One size fits all

Mark Gibis, vice president of sales and marketing for Doyle Systems: “Doyle Systems, the North American distributor of Alphasonics Ultrasonic Cleaning Systems, has been able to help our package-printing customers achieve greater efficiency in their roll cleaning processes. Alphasonics’ multiple-frequency anilox cleaners can safely clean increasingly higher linescreens and have a unique cleaning chemistry that can be neutralized and disposed of with normal waste water.

“One recent example is a customer that purchased a Megan model freestanding cleaning station to complement its acquisition of a wider web press. Originally, the printer planned to continue to use its existing machine for smaller rolls and use the Megan exclusively on its wider press. However, after several months of using the ultrasonic cleaner, the printer found that the Megan offered several advantages, such as safer and more thorough cleaning, greater ease of use, and lower maintenance when compared to its existing system. Because of these efficiencies, our customer was able to reduce its cleaning turnaround times by 600 percent, and has since mothballed its original machine.”

Clean sleeves

Christine Duggan, marketing communications for Flexo Concepts: “Recently, the flexographic industry has seen a dramatic increase in the use of anilox sleeves to enhance quality and gain production efficiency. In spite of the benefits, however, the industry been challenged with finding a safe and effective method for deep cleaning.

“The MicroClean™ System by Flexo Concepts is an off-press anilox cleaning machine that uses specially designed plastic media to gently remove dried inks and coatings from the anilox engraving, restoring cells to their original volume.

“A leading producer of value-added film and flexible packaging products for the food, personal care, medical, industrial, and agricultural markets, is one package printer that turned to MicroClean™ to clean its anilox sleeves. The company recently purchased a second MicroClean™ unit, model 160, following its success with using a model 120 to clean sleeves in its Oklahoma plant. Prior to using MicroClean™, the sleeves were being cleaned by hand, a messy task which failed to thoroughly restore the anilox engraving.

Baking blast

Jim Heffer, president, Anilox Roller Cleaning Systems: “Anilox Roller Cleaning Systems (ARCS) provides a cleaning service and sells the equipment that uses Arm & Hammer baking soda to efficiently remove the most resistant material from our customers’ anilox rollers. This soft crystal [baking soda] breaks down and performs a gentle cleaning process without damage to the cells or the cell walls.

“A recent customer, Richard Adams, plant manager at Rock-Tenn Company in Nicholasville, Ky., encountered dry ink in the cells of his rolls. This was found to be extremely stubborn to remove and could not be cleaned by conventional methods of chemical application and manual scrubbing.

“To address this problem, Mike Wyatt, general manager of ARCS’ southern region, used an on-site cleaning unit manufactured by Sani-Blast and attached a traverser with a vacuum recovery system to the Roland press. One hour later, the 60-inch rolls were clean and checked with the Capatch for volume readings. Several rolls that were cleaned doubled their volumes from the original BCM readings. This quality check ensured that the rolls were at the level necessary to provide sharp, consistent color densities necessary for repetitive color matching on various jobs.

Deep clean

Joseph Ialacci, president of Magnum Research Corp.: “One of our regular flexographic printing carton customers who regularly ordered our Flexo Kleen Plus anilox roll cleaner recently asked what we recommended for periodic deep cleaning. Flexo Kleen was working for [the carton converter] as a regular cleaner, but felt [it] needed to use an aggressive but safe, once-a-week-type cleaner to remove and clean the extremely stubborn ink dried in the cells. [It] thought of using a more caustic cleaner to get rid of stubborn embedded dry ink that wouldn’t wash off, but the high pH could have damaged the cells. Other methods such as ultrasonic baths and media blasts required them to take the rolls off the presses for cleaning, sacrificing printing time they couldn’t afford to lose.

“In lieu of offering a stronger, more hazardous liquid cleaner, we introduced our new AniPaste anilox roll gel to the pressroom manager. This viscous, gel/paste-type fluid could do the deep cleaning they needed without removing the rolls from the press and it wasn’t a volatile chemical so it couldn’t damage the anilox rolls. Users simply let the product soak into each cell, then wipe clean with a standard printer’s rag and flush with water and/or isopropyl alcohol.

“The non-abrasive cleaner does not contain any pumice-type material, which has been known to scratch and, more commonly, clog cells. The special blend of chemicals dissolves all water-based, UV, and solvent-based inks, and wet or embedded dry inks by soaking into the ink. The carton printer then halted its research of other cleaning methods once it found success with this, and continues to use it to do the periodic deep cleaning.” pP

No Excuses!

Loss of color strength or coat weight is a common problem for the majority of flexo printers and all too frequently it is because the anilox cells are plugged due to lack of cleaning. The excuses for failure to clean rolls are all too familiar and include:

• We don’t have the time to do it;

• We don’t have the equipment or solution to do it;

• My operator won’t do it;

• My manager won’t let me take the time to do it;

• I don’t know how to clean a roll; and

• I was not aware that cleaning a roll was important.

With regular daily roll cleaning, a wealth of benefits can be achieved, including:

• Improved overall performance from the roll;

• Greater durability and hence, longevity from the roll;

• Higher speeds;

• Improved print and coating quality;

• Reduced scrap;