Some things can function just fine when they are dirty. Small children, for example. Most things cannot, and the anilox roll is most certainly among them. If the cells of an anilox roll are not free of dried inks or coatings, they are unable to deliver the right amount of ink to the substrate. There's no getting around that truth.
Flexographers clean their anilox rolls in a variety of ways, as well as at different frequencies. Joe Walczak, president of Sonic Solutions, a manufacturer of ultrasonic cleaning systems, says that he has a customer "who faithfully cleans his anilox rolls once a year." Seasoned flexo people might choke at that, although some clean their rolls monthly. The consensus among most converters is to clean the rolls as often as possible. If they cannot be cleaned using one of the four methods discussed herein--water wash, ultrasonic, soda blast, and plastic media blast--they should at the very least be brushed with a detergent and the proper type of brush.
"A lot of people still clean by hand, using stainless steel brushes and cleaners," says Dave Burgess, vice president of sales for MicroClean, a plastic media blast system. "The mechanical action at the top of the cell with the brush can get it clean. We're not talking about 700 or 800 line count rolls here, just the lower count aniloxes. Brush cleaning is not very consistent from operator to operator. Even if it's the same operator it might differ, depending on how much time he has."
Hand cleaning is truly inexpensive. Other methods require capital investment with the goal of keeping those other investments--the anilox rolls--performing well every time. Here we examine four such systems, each different, that have shown to be effective in removing unwanted materials from the cells of anilox rolls.
The ultrasonic cleaning systems produced by Sonic Solutions have succeeded in the narrow and midweb markets. Today, says Walczak, the company is working with engineers to develop a system for the wide web market, where moving anilox rolls around the shop is no small matter.
In the ultrasonic system, the anilox roll is exposed to a bath of solution that facilitates the cleaning process. "The ultrasonic process acts more like a vacuum cleaner to remove the debris of the cells," Walczak says. "We have developed the 90-10-max5 rule to help people understand how it works best: 90 percent of the cleaning process is allowing the rolls to soak...