DPP2001: International Conference on Digital Production Printing and Industrial Applications

Print Technologies and Design Concepts for

Hybrid Printing Systems
Walter d’Heureuse and Helmut Kipphan
Heidelberger Druckmaschinen AG,
Heidelberg, Germany
Abstract strength of the individual print technologies. Especially
for digital production printing the combination of
The several printing technologies, conventional (e.g. computer to press with offset direct imaging technology
offset, flexo) and non-impact printing (NIP) (e.g. electro- and an ink jet imprinting unit (page wide) is also
photography, ink jet) have their special applications, described.
strengths and weaknesses. This is especially visible when
considering the economical run-length, the print quality, Introduction
the cost structure in general and the ability to vary the
image during the print run. The combination of different In today’s market, there is an ever growing demand for
printing technologies can create efficient and powerful print products that fit the special, individual needs of the
production possibilities and systems such as in-line customer, or a whole customer group. Personalized print
imprinting, personalization and coating (print finishing). products (i.e. names and/or addresses that vary from
This paper mainly discusses hybrid-systems, print to print in an otherwise fixed print image) and
combining conventional and Non-Impact Printing segmented print orders (i.e. parts of the print run that are
technologies (e.g. offset with ink jet), but also discusses modified) try to meet this demand.
hybrid-systems of NIP with NIP (e.g. electrophoto- At the same time, the market requires high print
graphy and ink jet) and conventional with conventional quality, short times for completing the whole process
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(e.g. offset with flexo) as shown in figure 1. from order to delivery, and the usual cost structure for
The hybrid-systems of conventional with NIP (e.g. medium run lengths. In order to meet these demands,
offset with ink jet or electrophotography) can achieve the companies have to make use of the special advantages of
superior image quality associated with conventional the various printing technologies and integrate these in a
technologies while adding customized information on a complete workflow for the production of a print
1-5
page by page or job by job basis. product.
The attributes associated with the various Hybrid systems, combining the strengths of different
technologies in hybrid printing technologies such as the printing technologies in one printing system, are capable
necessary paper specifications, speed and architecture as of producing special print products while maintaining a
4
well as examples of existing and possible hybrid-systems high level of economic efficiency and productivity.
are described. These systems take advantage of the

1
Figure 1. Combination of various printing technologies to set up hybrid printing systems.

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 DPP2001: International Conference on Digital Production Printing and Industrial Applications

Printing Technologies for Hybrid Printing technologies. From an economic efficiency point of
view, a very fast system should not be combined with a
It is evident that every technology has its own special slow one. The requirement to print with variable speed,
applications which can be characterized by the run for instance in case of feeding difficult paper, might
length, the quality of the print, further processing reduce the variety of combinations. In table 1 the most
options, cost structure and economic efficiency. relevant properties of print technologies are shown for
The diagram (fig.1) gives an overview of the most building up hybrid systems.
important conventional printing technologies requiring a
master as well as non-impact technologies which operate Table 1. Selected Important Features of Print
without a master and shows how so-called hybrid Technologies (see also fig. 1)
printing systems can be set up from a combination of Offset - transfer of one ink film/color separation
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these technologies. Production on sheet or web material (around 1 micron ink film thickness) with
using the relevant inks is possible. Sheet-fed printing high pressure onto the paper
systems are generally characterized by a higher degree of - almost independent of paper substrates,
format flexibility, web-fed systems by a higher but limited to plastic material
productivity. Printing is done on different substrates such - high print quality
as uncoated and coated paper, cardboard and also plastic - high speed (up to around 4m/s in sheet-
film material. The different substrates require special fed) and variable speed is common
inks tailored to the printing process itself and to the use - ink is not dry (exception UV-ink)
of the end product (in- or outdoor, food packaging, etc.). - ink cost is a very low percentage of the
The highest print quality is achievable with offset TCO (total cost of ownership)
(with the exception of gravure printing), in particular for Flexo - ink film (around 1 micron) with
multicolor images. High printing speed is possible “kissprinting” onto the substrate, but also
(sheet-fed up to around 4 m/s and web-fed up to 15 m/s) high ink/varnish film thickness possible
and the printing plates are produced quickly and (around 2.5 microns)
economically compared to other technologies. - printing on various substrates
Flexographic printing technology is especially - print quality not as good as offset
suitable for printing with varying inks and ink/varnishing - high speed and variable speed
systems particularly in high film thickness. - UV-curing inks are preferred (fast drying,
High ink film thickness is also applied with gravure good quality and high density
and screen printing. Gravure printing is however only of - ink cost is a very low percentage of the
low importance in connection with hybrid printing TCO
systems due to the expensive production of the printing Screen - transfer of ink film with low pressure
plate/cylinder. Rotary screen printing is preferred for - technology is preferred if very high
very high ink layers with high color density. densities (ink film thickness up to around
NIP- printing technologies, such as ink jet and 12 microns) or special effects are
electrophotography, make it possible to print a variable requested
image page per page but in general at a lower print - printing on various substrates
quality and higher cost per page than with offset or Ink jet - no contact with print substrate
1,6,7
gravure printing. - very low viscous ink (nearly like water)
The combination of various printing technologies - print quality dependent on substrate;
can bring about very interesting production options with penetration into the substrate (spreading)
both a high degree of economy for the printing company or non-wetting the "glossy" substrate
and benefit to the customer. Figure 1 also shows how surface (UV-curing inks and hot-melt inks
technologies can be combined with hybrid systems, are less “critical“)
merging conventional technologies, NIP-technologies or - speed up to around 2 m/s (400 ft/min),
conventional with NIP. variable speed is possible
When using hybrid printing systems the - drying, depending on ink type
characteristics of the printing substrates, ink acceptance, - ink cost is a high percentage of theTCO
print quality expectations and paper transport are of Electro- - transfer of toner by contact with print
particular importance. The combined printing photo- substrate and electrostatic field (toner layer
technologies have to fulfill requirements and must be graphy thickness around 5-10 microns)
well suited to each other. The type of drying and fixing - overall print quality worse than offset
process used to attach the ink to the substrate largely - limited printing substrates
determines the sequence of printing. Chemical and - speed up to around 1 m/s, no variable
physical reactions of the inks with each other (e.g. speed (control of process) in general
decomposing or non-wetting) must also be taken into - toner fixing usually by heat and pressure
consideration. Furthermore the design of high economic - ink cost is a very high percentage of the
print systems are determined by the maximum and TCO
reasonable printing speeds of the respective print

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 DPP2001: International Conference on Digital Production Printing and Industrial Applications

Concepts and Examples of Production with an ink jet printer for imprinting additional
1,6
Systems Combining Different Printing information in spot colors. The electrophoto-graphic
Technologies printer is the main system and can print a page-wide
image. The ink jet unit (piezo drop-on-demand, using
Combination of Conventional Technologies hot-melt ink) for imprinting spot colors can only print a
Within conventional printing technologies, hybrid width of around one inch per head. Several print heads
systems that combine offset and flexographic printing, (e.g. eight) can be positioned across the width of the web
such as sheet-fed offset presses (see fig. 2), are already and each head can print with a different color.
well-known. The latter have an attached coating unit for Highlighting of names and results in bills or lists is done
printing on the whole surface or partial (spot coating) with this printer. It is fast, up to around 1 m/s (200 fpm,
application of a coating onto a high-quality multicolor 240 dpi), and the quality of the printed image/text is
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print produced in the same press. With these systems it acceptable. A multicolor electrophotographic system
is also possible to produce colored imprints using a capable of this high speed and also suitable for this type
flexographic plate, for instance, with special effect of work (black and one or two spot colors) is not yet
coatings or special colors (spot color). The coating or available for cost reasons.
varnishing unit consists of a plate cylinder, a chambered
doctor blade inking unit and an impression cylinder. The Combination of Conventional and NIP-Technology
varnish is laid on top of the offset ink, which is not yet Combining conventional offset or flexo with a NIP-
dry. In this example, drying of ink and varnish (or technology is shown in figures 5 and 6. Offset and ink jet
special effect inks) is done by an IR-dryer. printing are shown in figure 5 are similar to the
demonstration by Heidelberg as a technology/concept
study at Drupa 2000 (at Drupa with a single color
Quickmaster). The high quality fixed image is printed on
the QM DI 46-4, a 4-color offset press with direct
1,8-11
imaging technology, and the imprinting, which adds
variable information to the offset print with one color, is
done over the complete sheet width with ink jet. At full
speed, 10000 A3-sheets/hour are printed. The ink jet
imprinting unit is based on the piezo technology from
Spectra and images with 7680 independently addressable
nozzles (325 mm/12.8” wide) at a resolution of 600 dpi
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Figure 2. Multicolor sheet-fed offset press with coating unit as and 38 kHz at full speed (1.6 m/s, 320 fpm). At the end
a hybrid printing system combining offset and flexographic of the imprinting unit a UV-dryer is installed to cure the
printing UV-offset ink as well as the UV-ink jet ink. Only one
dryer is needed to dry/cure the images of both printing
units simultaneously. After passing through the UV-
Another example of the combination of dryer the inks are completely dry and the print is ready
conventional printing technologies is demonstrated in to ship or for additional finishing processes. Since the
figure 3, a label printing press with flexo and screen ink jet print head has a short distance (about 1 mm) – no
printing units, and an additional unit for hot-foil contact - to the paper surface with the wet offset ink, it is
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stamping. UV-dryers are installed between all units to possible to install the imprinting unit after offset
cure the UV-ink. Wet-on-wet printing, that is without printing. With sheet-fed printing it is preferable to print
intermediate drying, is not possible in multicolor the fixed image first and then at the end of the paper
flexo/screen (like in offset). The different printing units travel the variable image. The workflow for reprinting
are designed in such a way that they can be changed sheets in the event of print interruptions (e.g. paper
according to the special print job requirements. misfeed) is easier to handle. (In electrophotography the
photoconducting surface or the intermediate carrier has
Combination of NIP-Technologies contact to the substrate; the imprinting unit therefore has
Figure 4 shows a system where electrophotography, to be installed before offset printing or the offset ink
for high speed monochrome printing, has been combined must be dried in advance.)

Figure 3. Hybrid printing system for label printing combining flexography, offset and screen, as well as letterpress for hot-foil
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stamping/embossing (CombiPrint, Goebel/Drent)

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 DPP2001: International Conference on Digital Production Printing and Industrial Applications

continuous ink jet technology) are spread over the length

of the last impression cylinder of the offset press. Only
columns can be printed since there is no overlap of the
heads.
Figure 7 shows a possible design of an
electrophotographic printing unit installed in a larger
format sheet-fed offset press. The dryer of the offset ink
(UV-curing ink) is positioned downstream of the offset
units. Instead of an electrophotographic system it is of
course possible to install a magnetographic, ionographic
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or ink jet system.

Figure 4. Hybrid printing system combining the NIP-

technologies of electrophotography (single-color printing) with
ink jet imprinting system for multicolor (spot color) imprints
(InfoPrint 4000/Info Print Highlight Color, IBM/Accent Color
Sciences)

Figure 6. Hybrid printing system: Multicolor offset printing

press with ink jet imprinting system for numbering,
personalization, addressing and segmentation of the job
(Domino/Heidelberg)

Figure 5. Digital hybrid printing system using the combination

of offset and ink jet technology (Heidelberg)

The hybrid printing system as shown in figure 5 is

modular in design (the imprinting unit is not rigidly
incorporated in the computer to press offset system).
Figure 7. Hybrid printing system combining offset printing for
This offers benefits with regard to the flexibility of the
multicolor printing with NIP-technology for the imprinting unit
printing system and the modular structure of different
to produce partly variable contents from sheet to sheet
model variants. The complete print job can be processed
(Heidelberg)
with regard to its fixed and variable image content using
digital job definition. Digital in-line imaging of the
master prior to print start is used for the fixed image The combination of an electrophotographic system
portions, and real-time imaging during printing is used based on liquid toner with flexographic printing units in
for the variable page content (a detailed description of a web-fed label printing system is shown in figure 8. The
the hybrid system and the design of the print head is electrophotographic printer in front of the flexo units can
given in the presentation of Yong Zhou/Clemens print variable multicolor images. The web is fed
Rensch; Applications of Page Wide Piezo Ink Jet intermittently (because the installed electro-photographic
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Printing to Commercial and Industrial Market ). printing system is a multipass system, needing 4 cylinder
1
An early installation of an imprinting system based revolutions for the multicolor print ). The flexo units
on continuous ink jet print heads and used especially for have to “wait” (turn without contacting the web) for the
1
numbering and personalization is shown in figure 6. next variable image. The toner image is fixed on the web
Eight separate print heads (with multi-deflection before it enters the flexo unit.

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 DPP2001: International Conference on Digital Production Printing and Industrial Applications

Figure 8. Digital label printing system with NIP-multicolor printing system (electrophotography with liquid toner; Omnius, Indigo),
flexographic printing, and finishing equipment for coating, laminating, and die-cutting (DO 330, Gallus/Indigo)

1
Figure 9 shows the components of a hybrid various printing technologies and hybrid printing
printing system for the production of print media by systems is being increasingly taken for granted. It is
web-fed offset. A direct imaging imprinting unit for also essential for successful economic production of
non stop plate change (segmenting the job) is high quality print media in short throughput times.
positioned in front of the multicolor offset printing
system (printing identical images). The imprinting References
system with ink jet (non-contact to the web) for
individual text or personalization is integrated after 1. Kipphan, H. (editor, author): Handbook of Printmedia -
13
conventional printing. Drying of the ink can take place Technologies and Production Methods. (Engl. Edition
after all printing processes. will be published in May 2001);
Handbuch der Printmedien - Technologien und
Produktionsverfahren. Springer, Heidelberg 2000.
2. Kipphan, H.: Computer to ... –Technologies; New
Developments in the Graphic Arts Industry for
Producing Multicolor Printed Products. Tenth
International Congress on Advances in Non-Impact
Printing Technologies (Proceedings). The Society for
Imaging Science and Technology (IS&T), Springfield
(VA) 1994 pp. 301-306.
3. Kipphan, H.: Digital Multicolor Printing; State of the Art
and Future Challenges. SPIE Proceedings “Color
Hardcopy and Graphic Arts IV”, Vol. 2413, Bellingham
Figure 9. System study: components of a digital hybrid (WA) 1995, pp. 7-31.
printing system for web-fed printing for the production of 4. Kipphan, H.: Digital Multicolor Printing and Printmedia
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segmented, personalized/individualized print media. Production – Status, Trends, Challenges and Innovations
in Technology, Equipment and Market. 42nd FINAT
World Congress (Proceedings). FINAT (The
Conclusion International Association for the Self Adhesive Label
Industry), The Hague (NL) 1999.
Various print technologies may often be in competition
5. Kipphan, H.: Future Challenges for Digita Offset
with each other for the production of print media.
Printing. Advances in Printing Science and Technology
Whether using masters/printing plates or the NIP-
(vol. 25)- Advances in Offset Printing (ed. J. Anthony
technology, every technology has its advantages for
Bristow, IARIGAI). Pira international, Leatherhead
specific applications, types of production and
1999, pp. 127-132.
production strategies.
6. Kipphan, H.: Status und Trends in Digital Multicolor
As described the combination of various printing
Printing-Technologies, Materials, Processes,
technologies (hybrid printing systems) can create
Architecture, Equipment and Market. NIP 13:
powerful means of production, making special
International Conference on Digital Printing
production methods and strategies possible. It is to be
Technologies (Proceedings). The Society for Imaging
expected that an increasing number of combination
Science and Technology (IS&T), Springfield (VA) 1997,
systems will be employed for the in-line production of
pp. 11-19.
printed matter, especially with ink jet technology for
7. Kipphan, H.: The Future of Printing: Changes and
variable imprinting and segmentations. With the help of
Challenges, Technologies and Markets (Proceedings).
different digital printing technologies it is possible to
Color Imaging: Device-Independent Color, Color
meet the most diverse, job-specific customer
Hardcopy, and Graphic Arts III. SPIE – The
requirements. The use of production systems based on

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 DPP2001: International Conference on Digital Production Printing and Industrial Applications

International Society for Optical Engineering, San Jose Biography

(CA) 1998, Volume 3300, pp. 2-13.
8. Kipphan, H.: Direct Imaging in Theory and Practice – Walter d’Heureuse joined Heidelberger Druckmas-
Computer to Press vs. Computer to Print. TAGA- chinen AG in 1982. He managed a design department
Proceedings, Rochester (NY) 1996, pp.589-612. for 10 years and has worked as a Senior Manager in
9. d’Heureuse, W.: Direct Imaging in “Advanced and Future Technologies” department since
Bogendruckmaschinen, Technische Lösungen und 1992. He studied mechanical engineering at the
Einsatzgebiete. Wissenschaftliche Tagung der Print- Technical University of Darmstadt and held the
Medientechnik RAPO 96 (Rationalisierung in der executive R&D position at a duplicator company in
Polygrafie). Technische Universität Chemnitz-Zwickau, Germany (former Pelikan Informationstechnik). He is
Institut für Print- und Medientechnik 1996. the holder of several patents.
10. Kipphan, H.: Imaging Systems for High-Quality Digital Dr. Helmut Kipphan did his apprenticeship as a
Production Printing. Focal Paper 4300-01 at toolmaker at HEIDELBERG. He studied mechanical
IS&T/SPIE’s 13th International Symposium; Electronic engineering in Mannheim and at the University of
Imaging 2001, Science & Technology Conference: Color Karlsruhe. Doctoral thesis and professor in
Imaging: Device-Independent Color Hardcopy and measurement technique. In 1978 he joined Heidelberger
Graphics Arts VI. San Jose (CA) / Heidelberger Druckmaschinen AG again as a research engineer. He
Druckmaschinen AG 2001. has held several management and executive positions in
11. Schmitt-Lewen, M.: Multicolor Production Printing R&D and technology/product development. Since 1992
Using Computer to Plate Technologies (this conference: he has held the position of Senior Vice President for
IS&T/DPP 2001, Antwerp 2001). Technology and Innovation Research (now: Advanced
12. Zhou, Y.; Rensch, C.: Applications of Page Wide Ink Jet and Future Technologies), dealing especially with new
Printing to Commercial and Industrial Market (this and future technologies for digital printing production
conference: IS&T/DPP 2001, Antwerp 2001). with conventional and NIP-technologies. He holds
13. Hübler, A. C.: Eindruckwerke für Rollendruckmas- leading positions in international committees within the
chinen. Wissenschaftliche Tagung der Print- graphic arts industry and industrial joint research. He is
Medientechnik RAPO 96 (Rationalisierung in der a member of IS&T and the TAGA board of directors.
Polygrafie). Technische Universität Chemnitz-Zwickau, He is the holder of many patents, a speaker at various
Institut für Print- und Medientechnik 1996. international technical conferences, author of several
publications as well as author and editor of the newly
published “Handbook of Print Media – Technologies
and Production Methods”.

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