Mark Vruno

Why is maintaining press rollers important?
July 12, 2007

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Question: With all the automation on the newer offset printing presses, my crews either forget about maintaining rollers—or they think it’s not necessary anymore. How do I stress the importance of basic maintenance to them?

Answer: It’s true that printers have benefited tremendously from new advances in press technology. Features such as automatic blanket washers and cleaning devices are a few examples of technologies that have reduced maintenance time and increased overall productivity and efficiency.

No Time for Maintenance?
But basic maintenance and its impact on overall print quality and press productivity is often not given enough consideration due to the everyday pressures to produce. Some of these fundamentals can have a tremendous impact on the bottom line.

It Doesn’t Take Long …
Many printers have had this experience: After a new press is delivered and the installer and demonstrator finish their jobs, the machine looks pristine, yields excellent print quality and generally delivers everything they paid for. But within months, print quality and press performance can change, even though they didn’t alter a thing in their operation. This may be the result of overlooking the basic maintenance the press needs to perform optimally.

Roller Coaster Quality?
Let’s first look at press rollers. Lack of roller maintenance can result in streaking, hickies and ink feedback to the metering rolls. But it’s easy to control these problems with a simple procedure: First, remove the ink with a good quality blanket and roller wash, followed by a water rinse to remove the surfactants contained in many of today’s washes—especially the water-miscible types. Use plenty of water to avoid stripping, poor color control, plate blinding and picture framing.

That Glazed Look
Next, examine the rollers for evidence of glazing (shiny appearance). Glaze may be solvent- or water-soluble, or may even be present in layers of each on the rollers. Some products remove only solvent-soluble glazes, while others work on the water-soluble types. Ask your pressroom consumables supplier for suggestions on which products to use—he or she can show you how to use them properly on site.

This Calcium Is Bad
Another contaminant often found on rollers is calcium (a whitish haze). Calcium build-up on press rollers may cause a host of printing inconsistency problems, including poor color control. Removal of calcium may be accomplished using diluted acetic acid and repeated water rinses. However, there are specialty products formulated for calcium removal that are more efficient and assure no contamination of fountain solution or ink train after the rinse.

Don’t Forget Fountain Solution & Filters
Finally, make sure that the fountain solution condition is optimized. First, examine the condition of the solution chiller/recirculator. A clean, well-maintained reservoir is essential to the maintenance of water-ink balance and printing consistency. In addition to removing calcium, paper, ink, solvent/wash and spray powder contaminants must be removed. Restoring optimum performance doesn’t end with cleaning the tank. Filters in the system should be changed once a week. Lastly, make sure that the solution is properly mixed, as recommended by your supplier. If you use a blending unit to mix fountain concentrates with water, routinely check to see that output is correct.

Check pH & Conductivity Daily
In your day-to-day operations, you should monitor and record both pH and conductivity on a regular basis. If the pH raises more than 0.5 units, or if conductivity increases more than 1,000 microsiemens from your freshly mixed fountain solution, consider changing it regardless of age. Unless you have a recycling system such as FloClear, changing the fountain solution at least once a week is a good habit.

Click here to read another GAM “Ask the Experts” blog entry about the importance of measuring conductivity.

Posted by Mark Vruno on July 12, 2007 | Comments (0)