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.


Polymer-based Gravure Cylinder Technology for 
Gravure Industry

Chandramohan Seetharamiah Srinivasaraju, James Springstead, and Paul D. Fleming III, Western Michigan University; Harvey R. Levenson, California Polytechnic State University

The Gravure industry in North America has been declining and losing market share in package printing for several decades. Researcher, Chandramohan in the prior study summarizes and explains that this decline is mainly due to the overall cost of the conventional chrome cylinder impacted by 1) The number of steps associated with the cylinder preparation, 2) Inability to quickly turn around new cylinders for new and rerun hot jobs resulted in the storage of pre- imaged cylinders in the inventory 3) Conventional cylinder preparation method utilizes hazardous chemicals in the plating process, and the associated toxic chromium-six entering environmental systems of air, water, and soil is heavily regulated by the government and international environmental agencies. 4) The conventional cylinder preparation method requires certification from the government, which require a print business to comply with the rules, and regulations defined for Air and water treatment, training of the employees, use of personal protective equipment, documentation of the treatments, testing, and training, regular auditing, and certification process and its associated fee. The penalty associated with the violation of the defined rules from the print business and with the errors found in the documentation during audits sounds like a burden to the print business and hence they resist bringing the lengthy conventional chromium-based cylinder preparation process in-house. 5) The print business using conventional chrome-based cylinder process usually outsource the cylinder preparation process to a third-party company which further adds its profit margins along with the cost of resources, and transportation of heavy cylinders. This further increases the cost and delays the turnaround time of the cylinders needed for running the new and re-run jobs. Currently, many Research and Development companies inventing and optimizing novel polymer materials suitable for the gravure cylinder preparation system, which eliminates the need for the chrome plating process and addresses the solution to the fore mentioned reasons of declining Conventional chrome-based gravure cylinder technology.

The Gravure industry and printers in America would like to understand how effectively these novel polymer-based gravure cylinder preparation outperform the conventional chrome-based gravure cylinder preparation in terms of cylinder preparation process steps, cost, adoptable to current imaging equipment, and quality of print reproduction. The researcher will collaborate with the print business using the conventional gravure cylinders to estimate the cost advantage that polymer-based cylinders offer, their suitability to be used with existing imaging devices, and their ability to reproduce simple to complex graphic images and functional patterns using respective process color inks and conductive inks. Graphic image quality 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. If the novel polymer-based gravure cylinder technology is proven viable to replace conventional chrome-based cylinder processes, then it would change the market trajectory of the gravure industry to move towards the direction of regaining package printing market share in North America. Further, the novel polymer-based gravure cylinder would open doors of further research and optimization for other applications such as coating, printed conductive electrodes used in electronic gadgets, heat, humidity, pressure, and other various types of sensors used in medical, and electrodes printed on current collectors for energy storage devices.