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FLEXO Magazine : November 2013
What variables can be examined? Well, nearly all of them and the results of the process can be measured. They include: • Ambient Temperature • Ambient Humidity • Ink Viscosity •InkpH • Dryer Temperatures • Media Temperature Once these measurements have been taken, the next phase is to obtain real-time color measurement data along with the data received from the other print variables and feed it all into a centralized computer system that collects, organiz- es and displays it. The ability to simultaneously monitor both the real-time color measurement data and the other print variables allows the press operator to prevent color problems before they occur. The additional benefit is the press gets to color faster. A comprehensive process monitoring system needs to provide: • Real-time reporting of the process variable data • Real-time reporting of the process output data • The ability to set control limits on the data Density Delta E Dot Gain • The ability to compare results with reference colors • The ability to alert the operator if the process is going out of control Real-time data can ensure that the process is working as it should, but the operator also needs to know how the print process is trending. Is the color data on a trajectory to go beyond the acceptable limits? This can only be determined by examining trend data. Trending allows the operator to view the process output over time. This is where the power of process control really pays off. Being able to spot a continuing decrease in density or other result trend before the process is out of control avoids costly waste. The system needs to allow the operator to see the output in familiar formats and in easy- to-read graphs that facilitate continuous monitoring. The next step in the full process control loop is an inter- mediate one that can be implemented right away. Beyond presenting the operator with the trends in real time, this step allows the system to suggest changes to be made to improve process quality. This is accomplished currently through the use of Ink Check, a predictive system that tells the operator how many density points to increase or decrease in each col- or to achieve better results. This and other process sugges- tions could be made by the system to improve performance. But this is still not full automation, since the system is only telling the operator part of what needs to be done. The opera- tor may still have to go off and add extender, adjust printing pressures or decrease heater temperature. LooP CLoSed A closing of the loop is the final step in the journey, one that still seems elusive in the flexo world. With full automation, all adjustments are made by machines, motors and pumps that turn and tweak the press. With this system in place, the opera- tor sits in a room with air conditioning, music and a padded chair, controlling the process from a central computer while multiple presses go about their business printing. This vision may currently be out of reach, but it’s certainly not out of sight. Whether or not that vision ever truly comes, there is no reason to wait to begin implementing an automation process. Print providers today have the technology and capability to maintain continuous, consistent high-quality color. Using today’s spectrophotometric technology, print providers can produce color that is reproducible on any flexographic press, color that is consistent throughout a run and process results that are documented. n About the Author: Dan Dupuis is a manufacturing engineering and integration specialist. He has spent the last 11 years dedicated to the color measurement industry and currently manages the building and integration of spectrophotometers into printing presses worldwide for Techkon USA. 56 FLeXO NOVEMbEr 2013 www.flexography.org Submersible Longer Life Tighter Tolerances Higher Quality No Ink Penetration The new HD.WaterProofTM sleeves from Apex represent a real “sea change” for the flexo industry. Lightweight and easy to clean and handle, Apex HD.WaterProofTM sleeves ensure greater consistency and a higher quality print throughout. The revolutionary design minimizes ink penetration, leading to increased life expectancy and substantially lower costs. So why not take the plunge and see what next generation anilox sleeves can do for you? HD.WaterProofTM from Apex: leaving the competition high and dry. visit www.apex-groupofcompanies.com