Whether printing on labels, film, carton or corrugated, the demands on flexo printers to achieve the closest possible color match by their customers to the approved proof is ever increasing. The higher the demand for color accuracy, the more effort the printer must make to achieve that demand. Here’s how anilox inventory management can aid in that quest.
The errors in colors, or the Delta E between the print and proof, is measured with a densitometer and is used to:
- Determine the color difference of the print or proof from the original
- Determine how much the color has drifted during the printrun
- Remove density subjectivity (as much as possible)
To achieve the demands of accurate color, the operators typically stop the press to take a sample (a pull) of the job to determine if each color is accurate. Logically, this should be a relatively simple and quick task; after all, we know the substrate that is being printed on, the ink kitchen has carried out all their checks and has delivered ink of the correct density and viscosity for the job.
Yet for some reason, it often proves necessary to run the press to take a pull to check for density accuracy, then adjust the ink four, five or more times before the job is color correct. This ink adjusting to achieve color accuracy can result in many hundreds of meters of expensive material being wasted, and absorbs valuable production time. Many printer/converters have found over the past decade that, by managing their anilox inventories, they are achieving color density much quicker and reducing the number of pulls required, which has increased their ability to be more productive and logically reduce the waste produced.
How Anilox Inventory Management Can Affect Volume & Color
Many printers have carried out the test in this discussion, but it is worth reviewing: Anilox manufacturers will often supply a banded roll to determine the best ink carrying capacity or volume on the aniloxes to be used. A very small difference in anilox volume can give a very discernible difference in density, hence color when printing. From various print trials, it has been determined that a difference of 0.4 cm³/m², for process colors, on an anilox will give approximately 3 Delta E difference on print. Naturally, there are many variables here—the ink type, the substrate press, running speeds etc.—but it has proven to be a good and reliable guide over the past 10 years.
If the aniloxes were known to be within a close ink carrying capacity of each other and also laterally, then the job setup time on press will be reduced and the waste runoff material would also be reduced.
The ink carrying capacity—the volume—for each anilox is a vital component of each anilox. Using four process aniloxes as an example, if all are within 0.4 cm³/m² of the 3.4 cm³/m² stated by the anilox engraver when it was new, we will know there is a very good chance of setting up the press within two to four pulls.
The aniloxes were measured with the following requirements:
- Accuracy: of ±0.1 cm³/m² for process aniloxes
- Repeatable measurements of ±0.1 cm³/m² when measured on the same place
- Interoperability: the ability for different operators to get the same readings
- Ease of use with data archiving for anilox inventory management
- No time, or minimal time, lost in production due to measurement times
- Measurement differences between the devices to be minimal
For the examples in this article, the aniloxes were measured laterally along the anilox, on the left (operator), middle and right (gear) points. However, for wide aniloxes it is not uncommon to measure in five places across the anilox.
| Anilox | Stated Volume | Operator | Middle | Gear | Average | Variation |
| 1 | 3.4 | 3 | 3.1 | 3.2 | 3.1 | 0.2 |
| 2 | 3.4 | 3.9 | 3.8 | 3.9 | 3.9 | 0.1 |
| 3 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 0 |
| 4 | 3.4 | 2.8 | 3 | 3.3 | 3 | 0.5 |
As shown in Figure 1, measurements on anilox 1 show three readings of 3.0 cm³/m², 3.1 cm³/m² and 3.2 cm³/m², giving an average reading of 3.1 cm³/m² and a variation across the roll of 0.2 cm³/m². The variation across the roll and the difference from the desired 3.4 cm³/m² is within 0.3 volume, making it good for use.
Anilox 2 readings are 3.9 cm³/m², 3.8 cm³/m² and 3.9 cm³/m², giving an average reading of 3.9 (to one decimal point), with a difference across the roll of 0.1 cm³/m². With the volume being measured at 0.5 cm³/m² above the stated volume, we see a typical example of where time is needed to reduce the ink on press to achieve the correct color density.
This anilox, which may have been marked up with the lower 3.4 cm³/m² volume in error, or has been measured using an inaccurate method of measurement, should be rejected and returned to the manufacturer for re-engraving to an accurate 3.4 cm³/m² if time and waste is to be saved on press.
The readings for anilox 3 are all at 3.4 cm³/m², so this is a perfect anilox and is clearly fine to use on the press. Anilox 4 shows three reading of 2.8 cm³/m²; 3.0 cm³/m² and 3.3 cm³/m². Showing an average reading of 3.0 cm³/m² would normally be fine, but the difference across the roll is 0.5 cm³/m², which is beyond the acceptable limit and so the anilox needs to be returned for refurbishment.
Therefore, clearly aniloxes 2 and 4 should not be used on press and should be sent for refurbishing if setup time is to be reduced and many hundreds of meters of waste material are to be saved.
Improved Production Through Anilox Inventory Management
Typically, once users begin utilizing anilox inventory management and have had “out of specification” aniloxes refurbished, we get feedback that most printers are able to benefit from at minimum improvement of one hour additional production time per press per day, and a minimum of 15 percent reduction in setup waste.
We get regular feedback on the monetary savings, too. The savings are reasonably uniform in all countries; for sites with three presses, they typically vary from $330,000 to $550,000 per year. It’s certainly worth doing the calculation to get an indication of the savings for your own company.
About the Author: Phil Hall is the owner of Troika Systems Limited in the U.K. He has been involved in the print industry for almost 40 years, starting as support technician for Crossfield Electronics on the early color separation scanners in the 1980s, then progressed into sales and marketing over the intervening years. Phil started Troika in 1996, always having an eye for trying to improve production efficiencies, and in the last decade, with environmental considerations, reducing waste, he looked to develop products that could achieve these aims. For a personal illustration of the productivity and makeready waste benefits, please contact your regional Troika Systems representative or email: [email protected].
The aniloxes referenced in this article were measured with Troika’s AniCAM with Anilox QC, which the company says evolved from the demands from major packaging converters for an anilox measurement device with inventory management. The AniCAM with Anilox QC has evolved into one of the industry’s leading anilox measurement tool over the past 10 years and is in use with more than 850 printer converters and many major print groups globally.