Harper Anilox Rollers: Line Printing Roll Specifications

Anilox Inventory Recommendations for Line Printing

"Designing an anilox inventory without a clear vision of your goal is like putting a puzzle together without having a picture of the completed design."

Step ONE:
Anilox Inventory Recommendations

When designing an anilox inventory for printing line colors, you must first determine the ink film thickness (or anilox volume) necessary to achieve the full range of desired colors on a given substrate(s).

Once the ink film thickness has been determined, you can then specify the best anilox roll cell shape and line screen necessary to provide uniform, consistent performance.

To determine the necessary ink film thickness consider the following:

Always Print with the Thinnest Ink Film Possible.

As proven in hundreds of process printing tests, printing with the thinnest ink film possible provides the best overall graphic quality and consistency from run to run. (See anilox inventories for process printing, The SHarper System™, Specifying Anilox Rolls)

The following picture shows the difference in printing with a thicker versus a thinner ink film:

Imagine how much more difficult it is to print a line solid with a clean reverse type using a thick ink film that tends to spread into the open type. This same condition causes inconsistency of bar gain when printing bar codes.

Your Ink Formula

Be sure you are using the most advanced ink system available from your ink supplier.

Over the last ten years, flexo inks have advanced greatly, enabling printers to apply half the ink film thickness previously used. The result is tremendous improvement in flexo print fidelity.

When printing with the thinnest ink films possible, you also minimize the need to change out anilox rolls when switching from a line print to a vignette job, and you have the ability to print both line colors and half tones at the same color station.

The following diagrams compare typical anilox volumes specified for older ink system technologies (the magenta section) versus the lower anilox volumes used with today’s advanced inking systems (the yellow section). The lower volumes are a result of today’s higher-strength inks capable of printing desired density utilizing lower anilox volumes and thinner ink films.

Exception: Higher anilox volumes are sometimes necessary when using inks with special functional properties. (See number 4 below)

DISCLAIMER: The charts shown above should be used only as a guide. When determining actual specifications for anilox rolls, all factors listed throughout this article should be considered.

Substrate Porosity

When determining the minimum ink film thickness necessary to print a given color, substrate plays an important roll. This is true particularly when printing on paper substrates, where ink tends to wick into the liner and lose its reflective color or light absorbing properties.

In this case, you must consider the "hiding properties" of the ink film thickness to prevent "fiber wicking", where paper fibers tend to penetrate the ink film and show through to the printed line color.

Recent tests prove that advanced ink systems, running higher viscosity’s, "blanket over" these fibers better and provide the ability to run thinner ink films than those traditionally used.
Laminating and Other Ink Functional Chemistry Properties

Functional properties of your ink (how it performs under the packages environmental condition) are always a critical consideration in determining the minimum ink film thickness achievable for a certain color. These properties these should be reviewed with your ink supplier prior to determining anilox volume.
Environmental and Ink Consumption Considerations

One of the biggest and least discussed benefits of striving to achieve flexo printing using the least amount of ink possible are environmental outcomes. When printing with a thinner ink film, fewer emissions are given off by the ink. In fact, some customers have cut their emissions by up to 25%, simply by decreasing their anilox roll volumes.

Additionally, ink consumption is cut as a direct result of thinner ink film printing. When you print with less ink, you inadvertently use and handle less ink, resulting in cost savings on your bottom line.

In either case, you are always better off when printing with the thinnest ink film possible.

Step TWO:
(Anilox Inventory Recommendations)

The second step in designing an anilox inventory for printing line colors is to determine the anilox surface delivery system that will produce the necessary ink film thickness’.

This step is easy when using Harper’s Echocel ET2000™ anilox rolls and the service support coming from years of testing and application experience.

As a general rule, flexo printers should use the highest possible anilox line screen, without exceeding the 33% depth-to-opening ratio (see specifying anilox rolls).

Higher line screens provide optimal plate support (clean edges) due to the higher number of cells, and maximum rewettability of the anilox surface to minimize potential cell plugging (density loss during a press run).

Overly deep cells can cause ink plugging of the anilox during the course of a long run, creating downtime to re-clean surfaces. (see FTROP research showing density loss as anilox cells go deeper.)

To fast track your line screen specifications: For additional help in developing anilox line screen specifications, e-mail Harper’s technical service department or contact us directly from our contact information page.

We are here to help and are happy to review any questions or problems you are having with a current job.