Finding balance on the printing press is an operator’s highest goal and most difficult challenge because there are so many “noise” variables that can disrupt equilibrium throughout the press run. Anyone attending a printing workshop or symposium has learned that ink management is a popular topic because problems on a press run are not usually seen until after the ink is put in the press. Typically, the first place people look when there is a printing problem is the ink, which soon becomes a question of ink pH or viscosity. But what if you could remove this initial question on fundamental ink management from the daily production challenges?
There is a solution to control your ink equilibrium and minimize the number of ink-related issues during press runs. Imagine operators being able to spend more time focused on the quality control aspects that are highly visible to the customers. Wouldn’t that be helpful? In the next few paragraphs, I’d like to tell you about a way to achieve this type of balance through viscosity and pH control, explain a little about the importance of stabilizing your ink process, and dive into a few details of what this could look like in your press room.
Let’s begin with why it’s important. There are a limited number of press adjustments an operator realistically has control over: press speed, impression settings, dryer settings, ink pH and viscosity, web tension settings or feed roller pressure. On the flipside, there are many quality control points that an operator should be focusing on during a press run: color consistency, clean screens, crisp type, smooth solids, open reverses, color-to-color registration, print-to-cut registration, smearing/tracking, hickeys, fish eyes, missing impression, and ink scuff.
One of the biggest ink problems I see is that ink is often forgotten because 1) the demands of the quality control checks can be distracting and 2) inks are generally stable for a period of time which can cause them to be overlooked. When this happens, the pH will get too low or the viscosity will get too high.
Viscosity, by definition, is the measurement of the flow of liquid against itself. If an ink is too thick, you’ll run into problems where the ink doesn’t flow through the inking system properly. It won’t transfer into the cells of the anilox roller, back out onto the plate and then back off the plate to the substrate properly.
The chemistry of the ink is also very important. Water-based ink chemistry is monitored in part by measuring the pH of the ink. What is pH? It is the measurement of the concentration of hydrogen ions in a solution. Water-based inks typically fall between 8.5 and 9.5 on the pH scale for proper function on press. Too low of a pH can result in insufficient ink rewet, ink drying too fast, ink building up on the printing plates and causing dirty screen tints (not to be confused with too much ink volume for the LPI of the graphics), and insufficient resin and pigment cohesion. Thankfully, there’s a better way to manage ink with virtually no extra manual effort during job changeovers and clean ups.
Enter the automated ink measurement and control system. Automating one of the repetitive press adjustments makes logical sense to allow the operator to focus on the quality control points mentioned above. When the press operator has the press set up properly with impressions and ink settings, throughout the press run the ink is the main component that will change and require continuous measurements and adjustments. If you’ve spent time around a press or running a press, you can understand the value that an ink control system would bring to a crew, especially if printing three or four colors or seven colors plus coatings or varnishes!
On a personal level, having used an automated system, I would never want to go back to not using one because of the ease of use and how quickly I can troubleshoot printing problems by immediately knowing the pH and viscosity of the inks. With this information, I can rule ink out of the problem-solving process or establish ink as the issue right away.
Furthermore, I have found automated systems invaluable in making correlations between environmental changes and the frequency with which ink adjustments need to be made. In ideal climate situations (moderate temperature and humidity levels), inks might only need adjusting every half hour. If the temperature is excessive or the humidity is very low, the reality is that the inks need constant adjusting every fifteen minutes or even less. Have you ever taken the time to personally measure and make adjustments to water-based inks on press? If not, you might be shocked by how much time it actually takes to maintain ink on a four or five color job. Do your study over a few press runs, especially when in a high heat or low humidity environment, and see how much time a press operator will be distracted from monitoring product quality off the end of the press.
The following are my top eight end-user requirements that an automated ink monitoring and control system should have in order to bring value to the production floor through buy in and use. In other words, in my personal opinion, when you’re searching for an automated system, it should include these to make it worthwhile:
1) No extra work for the measurement device during color changeovers or clean ups.
2) Calibration stability over weeks of use.
3) Ease of recalibrating when needed.
4) Robustness of the measurement device – production floors can be tough on equipment.
5) Ability to be accurate when foam or microfoam gets in the ink.
6) Large GUI (graphical user interface) with well-thought-out design and user experience (as I get older, I value the use of larger icons and GUI layouts; my eyes are not as good as they once were!).
7) System expandability – meaning you can start out small for trial purposes and set up on one or two stations then later add more station measurement capabilities when you find value in the autonomous measurement system.
8) Planned maintenance ease. Can the measurement device be easily inspected and/or easily “power” cleaned on a less frequent basis?
On a final note, I would assume there will be a definite return on investment if you measured how much time press operators spend adjusting inks or measuring inks on press, not to mention the time spent trying to fix an ink after it has gotten out of operating specifications. Any production process can be improved. It is a given that inks will, by their very nature, get out of spec, so why not automate that process to improve printing consistency? In my opinion, the fact that there are controls or systems that automatically check the viscosity of an ink for you is a substantial help for press operators and a great way to minimize the number of problems that you run into in the printing environment. Any system that will do that and bring consistency to printing production is worth investigating.
To learn more about how to implement ink process control, contact your Pamarco representative or take a look at the links below for additional information regarding this topic: