Diese Website verwendet nur technisch notwendige Cookies. In der Datenschutzerklärung können Sie mehr dazu erfahren.

Zum Hauptinhalt springen
Logo, Startseite der Hochschule der Medien
Veranstaltungsbeschreibung

181401b Flexographic Printing

Zuletzt geändert:20.06.2022 / von Carlsburg
EDV-Nr:181401b
Studiengänge: Print Media Technologies (Bachelor, 7 Semester), Prüfungsleistung im Modul Commercial and Packaging Printing in Semester 4
Häufigkeit: nur SS
Dozent: Prof. Dr. Dipl.-Ing. Volker Jansen
Sprache: Englisch
Art: -
Umfang: 2 SWS
ECTS-Punkte: 3
Workload: Taught sessions: 30 hrs;
Preparation for exam: 60 hrs
Total: 90 hrs
Prüfungsform:
Bemerkung zur Veranstaltung: Englisch
Beschreibung: Content:

Categorising
Flexographic Applications
Flexographic Printing Presses
Principles of Flexography
The Image Carrier (types and systems)
Plate Chemistry
Plate Processing (technologies)
Halftone technologies
Inks
Printing Plates & Press
Manufacturing principles
Proofing and Plate Making
Mounting
The Pressroom
Substrates and Adhesives

The following topics are covered:

Week 1
Food packaging serves many purposes, from protecting the food to creating portion sizes to offer information on the product. However, what is not well known about food packaging is the different types of packaging available. In this section you will distinguish between various types of food packages and you will learn about their technical details.

Week 2
Flexo (Flexo printing process or Flexography) is a printing process which utilises a flexible relief plate or sleeve mainly made of photopolymer. It is essentially a modern version of letterpress which can be used to print on almost any type of substrate including plastic, metallic films, cellophane and paper with nearly all ink systems like solvent, UV or water-based inks. In this section you will receive an overview of the markets, what the products are and why flexography is a preferred process for flexible packaging printing.

Week 3
Flexographic printing plates are flexible photopolymer plates to directly transfer ink & images to a flexible substrate, paper or board. The printing plates are a critical element of the flexographic printing process and the quality of the printed image is largely dependent on the quality of the flexo plates used. In this section you learn why the choice of processing and the type of flexographic printing plates is important for the end quality of the packaging. You learn about the principals of the photopolymer plate making process and its specific workflow.

Week 4
Most flexo plates today are exposed using direct computer-to-plate technology (CTP). In this case, the unexposed film negative is supplied pre-laminated onto the photopolymer sheet, so that both layers can be exposed in the same piece of equipment. This poses a number of challenges to operators and influences the resulting image. By adopting high quality flexo plate production, many YAG laser equipment suppliers and photopolymer producers have able to incorporate a number of automated features into the plate making process, providing consistency throughout the process. This week we will concentrate on alternative ways of plate processing.

Week 5
Flexographic plate mounting is a critical step in achieving optimum print quality. Perhaps the biggest problem facing flexo printing is something called minimum dot. Made from a thick, flexible polymer material, very small halftone dots on flexographic plates cannot be safely reproduced. Using proper techniques in preparation, mounting and plate removal will allow the optimum performance of the mounting tape through the entire flexographic printing process. Plate mounting systems today are filled with features to help limit errors in the mounting process and to protect the operators from work place ailments such as repetitive strain injury. In this lecture you learn about different mounting methods and applications. We will concentrate of various combinations of tapes, cushions and plates for the reduction of dot gain.

Week 6
The precise metering of the ink that is transferred from the anilox roller to the plate is controlled by the doctor blade. Blades are made from either steel, hardened polymer or carbon fibre materials, and perform a vital function in the printing process. These metering devices are used on all flexographic machine configurations. There are three basic press configurations used in flexography (with many different variations, depending on the manufacturer). You will learn about metering devices and various machine configurations for the use of flexible packaging and paper and board printing.

Week 7
The line screens for flexo printing tend to be a bit coarser than conventional offset printing. Most traditional print is either 133 or 175 line screen. When flexography developed into a higher quality printing system, being able to reproduce colour separations, it was necessary to adapt halftone angles because the angles of the anilox rolls engravings could interfere and originate a moiré effect on print. This week we will focus on digital halftone screening, halftone angles and types of screening.

Week 8
Flexo printers face many challenges, including improving print quality, shortening make-ready times and reducing waste. Flexo press fingerprinting can help achieve these goals, The purpose of fingerprinting a press is to determine printability of text and lines, as well as quantifying dot gain values. Generally after a fingerprint run, a dot gain compensation curve, or DGC, is created to allow the printed tone values to match a standard. The reason for this session is the need for you to learn about dot gain curves, Grey Component Replacement and Under Colour Removal.

Week 9
Wettability of substrates and adhesion of ink has always been an important issue with packaging. In this section we will concentrate on the physics of wetting and adhesion.

Week 10
Surface Treatment - the act of modifying the surface of a material to change the physical, chemical or biological characteristics originally resident on the surface of a material. Surface treatments have been effective for many years in modifying substrate surface characteristics to promote the adhesion of flexographic inks films and papers. For papers, the partial absorbency of water-borne and solvent-borne inks into the substrate (and partial vaporization) is key for adhesion. However, the printing of water-based inks on a non-porous film or foil cannot rely on absorbency and partial vaporization. It relies on physical and chemical adhesion. This week we learn about methods of measuring surface tension of liquids and solids.

Week 11
Sorption is arguably the most important chemical processes governing the retention of nutrients, pollutants and other chemicals in the packaging material. We will talk about adsorption and absorption and learn more about the physics behind it.

Week 12
Test Exam

Week 13
Questions and Answer

Week 14
Excursion
English Abstract: Flexographic printing or flexography (often abbreviated to flexo) is a form of printing process which utilises a flexible relief plate, a photopolymer printing plate. It is essentially a modern version of letterpress which is largly employed for printing all types of substrate, including plastic, metallic films, cellophane, and paper. It is widely used for printing on the non-porous substrates required for various types of food packaging (it is also well suited for printing large areas of solid colour). The course deals with various pre-press processes, manfucature of photopolymer plates, flexographic printing and finishing.
Literatur: Every file for this lecture has been carefully researched and referenced. The entire material attached is for your private use only. No element is for publication on the Internet or for distribution on any publication tool.
Although all sources are carefully cited, this lecture is not for dissemination as it may contain images and text elements with third party copyright ownerships.
However, this lecture falls under the right of ‘fair use’. This is the right to use portions of copyrighted materials without permission for purposes of education, commentary, or parody.
A comprehensive bibliography is part of this lecture. It is available upon request.

Weitere Literatur finden Sie in der HdM-Bibliothek.
Internet: to be advised