Abstract

Printing has a unique history of process development as compared to nearly all other technologies; as a major technology it went for centuries unchanged. Gutenberg’s 1450 relief image printing process lasted without change for nearly 500 years until offset lithography became the dominant printing process in the 1960’s and 70’s. Offset continues to be the dominant process today with close to 90% of all printing volume. Emergence of Substitutes for Offset Printing No question that within just the past decade new significant technologies and systems have emerged challenging offset lithography at an increasingly fast pace now. A substitute will only survive if it can meet or exceed the benefits of what it is substituting for - in this case, inkjet for offset process. The increase in the emergence of new printing processes is brought on primarily by the digital age and the ability to develop revolutionary new writing systems and electronic image and process controls.

To date, however, the application of the new digital printing processes, primarily made up of toner and inkjet printing, resides with low volume short run printing production. When applied to longer volume press runs, digital processes have resulted in lower image quality, higher cost, and limited substrate options. A few manufacturers require an additional process of precoating paper so that their inkjet inks will adhere to conventional papers. This requires adding additional water to paper (paper does not like water), additional jetting heads, pumps, feed lines, component space, monitoring and controls, fluid reservoir and maintenance resulting in increased process complexity, cost, and paper use. Aside from these limitations, the processes themselves have had great difficulty with system stability and consistency of reproduction at run length. In addition, the rub off strengths have been weak. These limitations have kept digital printing from challenging color offset lithography for typical commercial color production length runs. As the reader will find here, testing shows and verifies that SCREEN Graphics Solutions Co. has now solved these great issues in the engineering of their 520HD SC inkjet web press.

Experimentation Discovers a new Printing Substitute for Offset Run Lengths In the fall of 2018, Image Test Labs conducted an experiment in conjunction with

Technology Watch NewsletterTM and SCREEN to have a process color inkjet web press match a modern sheet fed offset press manufactured in this case by

Heidelberg of Germany. This experimentation successfully resulted in the production of a Special Issue of Technology Watch Spring 2019 entitled Matching Offset with Inkjet Web - Making Some History. The technical section of this paper will address this experiment as well as prove that a SCREEN 520HD SC inkjet web press can economically produce the image quality of a commercial sheetfed color offset printer at a production length print run. In fact, as you will see, the SCREEN inkjet web press actually exceeded the stability and consistency of the Heidelberg offset press, breaking through the critical limitations that have kept inkjet from true offset production run length work. Significant benefits of the SCREEN 520HD SC Press derived from stability and consistency

1. Ability to economically produce a critical color image level over a long run length.

2. Ability to accurately predict the materials and processes used for the printed work.

3. Reduced paper waste on top of a 15-20% lower paper cost than a sheet fed offset press.

4. Faster get to color on press at makeready.

5. More accurate and fine-tuned price estimating to win more work.

6. More accurate scheduling.

7. Reduced environmental impact of press run.

8. The increased stability and consistency has produced a uniformity level required for the packaging printing market.

9. A reduced processing load requirement for inline error detection and correction systems.

Based on the above discussions, the SCREEN 520HD SC press is the first inkjet press to have successfully made the historic breakthrough into offset sheetfed commercial color production volume work on a modern printing plant floor.