DLC based Anilox Rolls Flexographic Printing Process
Chandramohan Seetharamiah Srinivasaraju, James Springstead, and Paul D. Fleming III, Western Michigan University; Harvey R. Levenson, California Polytechnic State University
The Flexographic printing process has seen many advancements in the process (Plate, Anilox, Ink) and machinery (press automation) to achieve better graphic image reproduction over the past decade. The primary purpose of the anilox rolls is to transport the determined quantity of ink onto the image carrying a flexible plate. The fabrication of the anilox rolls involves preparation of the ceramic powder for coating, thermal spraying of the bond coating and ceramic top coating, post-spraying followed by grinding, polishing, and laser cell engraving. The top coating of the anilox roll uses chromium oxide which is a hazardous chemical in the anilox roll preparation process, and the associated toxic chromium oxide entering environmental systems of air, water, and soil is heavily regulated by the government and international environmental agencies. The flexographic print business using conventional chrome oxide- based ceramic coating on the anilox roll, usually outsource the anilox roll preparation process to a third-party company which further adds its profit margins along with the cost of resources, and transportation of anilox rolls. This further increases the cost of anilox rolls. Currently, many research and development companies inventing and optimizing anilox roller coating materials to eliminate the need for the chrome oxide in-process and address the green solution to fabricate the anilox rolls.
The Flexographic industry and printers would like to understand how effectively Chromium Oxide Free, DLC Anilox rollers compare to the conventional anilox rolls in terms of ink transfer onto the photopolymer and elastomer plates and quality of print reproduction from these plates. In this study, the researcher will use photopolymers plates and elastomer plates applied with advanced surface screenings that form a graphic image. To evaluate the print quality, the researcher will identify graphic images and functional patterns for imaging them onto both the photopolymer and elastomer plates. Then, using the appropriate cell specification of DLC Anilox rollers, the respective process color inks, and conductive inks will be transferred onto the flexographic plates which in turn transfer the ink onto the substrate. The process will be repeated with the Conventional chromium oxide-based ceramic anilox rolls. The printed graphic image quality obtained from the print trials using both the types of anilox rolls will be evaluated qualitatively and quantitatively in terms of smoothness of the gradients, color density at various tone percentages on a step wedge, solid density, smoothness of the fine line, quality of reproduction of the text. The outcome of this study would help the flexographic industry and printers in understanding how well DLC Anilox rollers perform compared to conventional anilox rolls. Results of this study would encourage further optimization of the flexographic process parameters to use chrome-free anilox rolls which in turn reduces the cost of the rolls and allows printing businesses to bring anilox roller preparation in-house.