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A Matter of Decision

By Jason Cagle

July 30, 2018

It is possible to increase productivity and efficiency by addressing two key problem areas that impact all flexo printers alike. Over time, subtle shifts occur in print but often go unnoticed, both the good and the bad. In order to recognize these changes, the old saying about being too close to the coalface applies: It is necessary to step back and take a fresh look. Once identified, problem areas can be carefully observed and their origin thoroughly understood, and waste elimination can begin.

Two of the greatest contributors to decreasing efficiency and productivity are poor press speeds and press downtime, both capable of causing unnecessary delays and rework. There are enormous benefits in addressing these two over­arching with the proper data and a willingness to change.

Complementing advancements of the anilox roll, digitally imaged flexo printing plates have evolved by leaps and bounds since they were first introduced in 1995.

Productivity is defined by Webster’s dictionary as “the effectiveness of productive effort as measured in terms of the rate of output.” In other words, it is the act of increasing productivity that creates value on the bottom line. This type of growth is the way to happier customers, as well as greater profitability and sustainability. In this case, the way to increase productivity and efficiency is through a reduction of off-press activities and the ability to minimize lost press hours.

The end goal is to keep presses running for longer than they currently are and to lessen the effects of anything that increases downtime or slows the press. As the heart of the press, an incorrectly chosen or poorly maintained anilox roll is a major contributor when it comes to these problems. On the other hand, properly specified, properly maintained, and properly produced rolls deliver results. Another key component is the photopolymer plate. Calibration of the plate is required to meet graphic requirements utilizing various technologies such as flat-top dot, selected durometer, and plate-surface texture. Without proper plate-to-anilox calibration, difficulties are sure to arise. Most commonly, these obstacles include: slow press runs, costly double bumps, setup times, ink toning at press side, and general print fidelity.

There is clear evidence that the above-stated complications are truly the greatest culprits, stealing away profits through loss of efficiency. Substantiation of this claim can be clearly seen in data regarding make-ready time, and waste factors such as ink and substrates. Other major statistical indicators include the average number of jobs per shift, colors per job, startup waste, and starts vs. stops.

The chart below has been established as a general rule in the selection of anilox specifications. It is always best to start with a volume/BCM target, then establish the LPI of the engraving. This will confirm that the correct amount of ink is available to the plate and print, while ensuring the strongest roll. A properly specified anilox with a depth-to-opening ratio of 25 percent to 30 percent will consistently release ink and readily be replenished by the doctor blade chamber. This will reduce plugging and increase consistency in print and density.

The result of testing and auditing will help to identify problem areas and to align the company’s actual outcome with its goals.

While results show that there are differing and sometimes multiple problems that may stand in the way of achieving the desired productivity and efficiency, methods are readily available to help any printer realize their fullest potential. Through identification of ideal print packages that are based on what they wish to accomplish, bottom-line improvements can easily be made. When this occurs, there will be a greater print capacity, as well as higher and more consistent quality.

Complementing advancements of the anilox roll, digitally imaged flexo printing plates have evolved by leaps and bounds since they were first introduced in 1995. In the past, during long runs at converters, press operators would need to stop the press during a run in order to clean plates due to dirty print. Now, with the latest corrugated technology, converters are able to increase their productivity and efficiency by having less press downtime. These new corrugated plates are designed to easily release more ink, and this, in turn, allows for cleaner highlights and less downtime cleaning the plates.

However, it is important to keep in mind the relationship between the cells per inch (CPI) of the anilox and the images’ lines per inch (LPI) on the plate. The relationship between CPI and LPI is recommended to stay between 5:1 and 6:1. This means if a converter is running 150 LPI, they should have an anilox that is at least 750 CPI to avoid dirty printing. There are certain cases in which a converter is able to print with a lower CPI anilox to increase their volume, but this increases susceptibility to dirty printing.

The simplest means of identifying ideal print packages for achieving the desired outcome is to arrange for customer-specific testing and a banded roll test, dialing in the plate and anilox. Through these specialized services, plates can be calibrated with proper anilox rolls for much higher efficiency. The result of testing and auditing will help to identify problem areas and to align the company’s actual outcome with its goals.

Once these evaluations have highlighted the prominentit’s strongly encouraged to follow a maintenance program to provide for the greatest consistency in print. Data confirms that when volume drops 15 percent below the targeted BCM, it creates densitymore press-side ink toning/adjustments, and consequently, an increase in downtime. Through regular maintenance, this downtime can be greatly reduced.

In summary, before proper maintenance can become standard operating procedure, it is first necessary for printers to understand their starting point and to establish their goals. This is the key to overcoming these two problem areas of press downtime and reduced press speed. With the constant evolution of anilox roll and plate technology, becoming more productive and efficient is easier than one may think. In the end, once this tangible goal is established through the knowledge that comes from utilizing the services of experienced auditors and testing agents, true increases in productivity and efficiency are only a matter of decision.

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width=150Jason Cagle is application development specialist at MacDermid Graphics Solutions. He can be reached at jason.cagle@macdermid.com.

 

 

 

 

width=150John Rastetter is vice president of sales, flexo division, at Pamarco. He can be reached at john.rastetter@pamarco.com.