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Digital printing
finishing technologies making digitally
printed documents professional
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Abstract
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This presentation will discuss the importance of finishing technologies
that are used for the digitally printed documents.
The increased use of digital printing systems has caused the necessity
for the development of new finishing and binding systems for the documents
that are digitally printed. The finishing systems that have been developed
for this purpose, have their own specific characteristics that can be described
as follows:
The manufacturing of the systems is based on the factor that the documents
have smaller dimensions than traditionally printed sheets.
The production is done under the consideration of processing loose sheets
of paper rather, than folded signatures.
There is the necessity for manufacturing finishing systems where saddle
stitching, perfect binding and trimming must be combined.
There is the requirement for quality binding in comparison with traditional
finishing systems.
Quite important issue on finishing technologies for digital printing
systems is the requirement for digitally printed documents to be as good,
look as «professional» and function as the traditionally finished
ones.
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Keywords
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Contents
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- Digital printing
- Digital printing and its market position
- Relationship between digital printing and finishing:
- Comparison of digital and traditional printed documents finishing systems for digital printing
- The aim of finishing and binding technology
- Development of finishing and binding systems for digital printing machines
- Structure of the workflow for digital printing and finishing:
- Conclusion:
- Acknowledgements
- Bibliography
Digital printing
Early at the beginning of the last decade, the digital printing was
born. Within the years that followed, up to today, digital printing turned
to be the most significant technology for printed media production [SEY 98].
The term is used today in order to describe the systems and equipment
that produce printed or «printed» sheets or rolles of paper (and
other substrates) at one or both sides, by using different technologies of
imaging with one or more colours.
Furthermore, the term «digital printing» is used in order
to define the printing-imaging processes where the film and/or plate making
processes are eliminated and where printing or imaging takes part exactly
after the pre-press production process. In comparison with the traditional
printing processes Digital Printing can be presented at the
Figure 1
that follows:
Figure 1
. Comparison of processes
But, as we talk about printing, we deal with printed media, and it means
that printing systems or machines produce image on paper or other substrate,
no matter of the technology or process used (traditional or digital).
It is natural and of course necessary, that printed sheets or roles
need to be further processed in order to receive final printed documents that
can be delivered to the end customer. [WGA 98]
This post-press production is done by a wide range of finishing technologies,
systems and machines that have been developed and established for this purpose.
The first conclusions to this approach on digital printing is that digitally
printed documents need also to be finished and digitally printed documents
are also products on paper (or other substrate).
Figure 2
. Digitally printed documents.
A variety of leaflets, brochures, catalogues and books (courtesy of
c.p. bourg inc. New Bedford, MA, USA)
Previous
Table of Contents
Digital printing and its market position
Digital Printing Technology, after the first presentations (PRINT, IMPRINTA,
TPG) was also one of the main technological innovations at DRUPA '95, Imprinta
97 IPEX 98 and CEBIT exhibitions [NES 98]. It was also
in DRUPA 2000 exhibition. But the attraction of people dealing with this technology
was (and still is) concentrated, on matters of quality, especially in colour
digital printing. Not only potential customers but also sales managers and
officers from the supplier side, focus on printing quality and other characteristics
on printing.
Most of the people are still impressed by a colour document printed
digitally, ignoring the very important issue that this document must be as
good as the other documents that are printed traditionally. But also, they
must be delivered as finished products to the market where the final result,
the appearance and functionality of the printed document is evaluated.
Digital Printing came and established in to the market with an added
value based on certain advantages and characteristics that are important for
a rapidly changing environment in printed media [APE 98].
Among others are these characteristics:
- Short cut production time.
- Fast delivery.
- Printing on Demand.
- Personalization.
This is the strength of digital printing where printed matters go directly
from pre-press to print by eliminating the film and plate making production
stages, as it was mentioned before.
All these advantages concentrate on two main issues:
- Fast (to RAPID) delivery time and
- Imaging of the number of documents that are needed (POD – Printing On Demand).
But here comes the question:
DIGITAL PRINTING delivers fast WHAT? Loose A4 and/or A3 printed sheets
of paper only?
This can be done with laser or inkjet printers of all kinds.
This is not of course, the field where digital printing systems should
stay. The orientation of these systems is placed on commercial printing. This
area deals with final printed documents that can come into the market and
function exactly as the traditionally printed and finished ones [PIRA 98].
Therefore, finishing and binding for digitally printed documents was from
the first moment equally important as the printing quality, for example. It
was of course natural that at the first appearance of this technology, interest
should be given to printing quality. But this has to stop somehow, if we want
to have a complete view of the orientation of digital printing into the publishing
market [FRI 98].
Relationship between digital printing and finishing:
The technological advantages mentioned before gave to the digital printing
systems the innovative characteristics which enable a new technology to find
a position into the market.
But, thinks started to become difficult when digital printing systems
had to face the competition into the real the production, with the traditional
printing systems.
The first comparison took part in the field of printing quality. After
the improvement of the quality, size, printing speed and maintenance of digital
printing systems had to be compared with traditional printing systems [SCH 98].
Finally, the most important factor came into the surface:
The final product that will be delivered to the market, is a finished
and completed document at a form of leaflet, brochure, catalogue, magazine
or book.
This aspect was not an important one for a lot of people involved in
the Graphic Arts sector and still, people consider that finishing technology
is «given» and they have not to pay attention into this area [INC 97].
But, for someone that wants to play a role as a manufacturer, supplier,
salesman, or commercial printer within digital printing process, knowledge
and experience must cover all fields, including the technological development
and production process on finishing and binding.
It is true that manufactures that developed early enough finishing and
binding systems that can be adapted and connected with digital printing systems,
are now the leaders in this area. From the other side, some traditional suppliers
of finishing and binding systems stayed outside this area [DD 99].
As a conclusion to this section it is important to notice that digital
printing systems came into the marked with advantages such as short of costs
and production time in order to take a part of the commercial printing market.
This task can be achieved only if these systems can produce printed documents
that can be very professional.
Therefore, digital printing systems had to be integrated with finishing
systems that could make these machines as complete as possible.
Otherwise, they should stay at the level of photocopying machines or
color copiers that produce loose sheets of papers at an office environment [XER 99].
Figure 3
. Schematic drawing of a digital printing machine where a binding
system is connected on line (courtesy of XEROX HELLAS SA)
Comparison of digital and traditional printed documents finishing systems
for digital printing
There are different ways for development of Finishing systems for digital
printing. They can be classified as follows:
- On line and off line systems.
- Systems related with the dimensions of the printed sheet.
- Systems that combine different finishing operations and methods.
A first part of already existing finishing technologies has been integrated
into the digital printing machines serving some absolutely necessary functions.
These systems are already integrated from the very beginning at the
photocopying machines and include feeders, transfer of the sheets, collating,
delivery and pile systems and roll to sheet cutting systems.
Figure 4
. Schematic drawing of a digital printing machine, where rolls
of paper are printed
A roll to cut system is integrated into the machine (courtesy of IBM
Inc.)
But, the new generation of digital printing systems had to be equipped
with more sophisticated finishing systems that can keep the efficiency of
digital printing at a high level of speed and quality, and give the technical
possibility to produce no more a staple of loose sheets but a finished and
ready to deliver document like a BOOK.
Before we go deeper into this field, it is necessary to compare the
basic characteristics between traditional and digitally printed documents,
as it concerns the requirement for quality finishing.
The comparison will be more accurate if there is a definition on the
kind of the documents that are to be compared.
Digital printing systems that require finishing are those that print
mainly leaflets, brochures and books with softcover.
These printed matters are traditionally printed with offset sheet-fed
printing machines with the maximum size of 70x100cm (B3 format).
Therefore, we can define so far the following:
Art of documents:
- Leaflets
- Brochures
- Books
Main dimensions (of finished products):
- A4,
- B5,
- A5.
Main binding methods:
- Saddle stitching,
- Perfect binding
- Thread sewn binding
- Spiral binding.
In
Table 1, there are presented the main differences
of the semiproducts that are produced with the traditional sheet-fed offset
and digital printing processes:
| Offset printing | Digital printing | |
| Sheet dimencions | Up to: 50x70cm61x86cm70x100cm | Mainly: a4, a3or roll width:30cm50cm |
| Printed sheet characteristics (1) | 4, 8, 16 or 32 pages on both sides of the sheet (signature) | 2, 4 or 8 pages on both sides of the sheet |
| Printed sheet characteristics (2) | Sheet to be folded 1, 2, 3 or 4 times | Sheet to be folded 1or 2 times or mainly loose sheets |
| Offset | Digital | |
| Printed and folded sheet characteristics | Better quality, more stable by folding | Loose sheets, subject to damages while finished |
Table
1
. Offset sheet-fed and digital printing: main
differences between the two printing methods
The aim of finishing and binding technology
Binding and finishing is much older than printing and is used hundrends
of years before Gutenberg invented TYPOGRAPHY. Today the binding and finishing
methods are so developed that produce excellent final printed matters. Therefore,
the overall consideration in quality, is not only a matter of color separation,
pre press and printing but also a matter of finishing and binding [XER 96].
As a conclusion: Sophisticated digital printing systems have to be completed
with equally sophisticated finishing and binding systems in order to achieve
the quality that traditional binding systems and methods offer today. In that
case:
Did we had to invent the wheel once more?
Of course not.
What we needed was to consider how to develop concepts and technologies
that should allow the combination and/or integration of finishing and binding
systems with the digital printing systems.
Here, different approaches and procedures were developed but before
we go into this field it is necessary to describe shortly the traditional
finishing workflows and production processes (Print production - sheets of
paper in different dimencions -
Table 1 and
Table 2):
| Process | Machine/system | Semi product |
| Folding | Folding machines | Folded printed sheet |
| Gathering / collating | Collating machines | Collated sheets |
| Binding | Binding machines | Binded product |
| Trimming | Cutting machines | Finished printed product |
Table
2
. Finished product: book, catalogue binding
methods: perfect binding, thread sewn, combined
| Process | Machine | Semi product |
| Folding | Folding machines | Folded printed sheet |
| Collating - saddle stiching | Collating - saddle stiching machines | Binded product |
| Trimming | Cutting machines | Finished printed product |
Table
3
. Leaflet / brochure
Development of finishing and binding systems for digital printing machines
The production principles of the main finishing processes remain unchanged
and are presented at the images that follow:
Figure 5
. Principles of paper folding: knife (left) and buckle (wright)
folding
(courtesy of BTI-Hellas SA - Heidelberg Finishing Systems)
Figure 6
. Traditional folding machine
(courtesy of BTI-Hellas SA - Heidelberg Finishing Systems Stahl GmbH)
Figure 7
. Perfect binding production process: 1. clamping; 2. cutting;
3. notching
(courtesy of BTI-Hellas SA - Heidelberg Finishing Systems)
Figure 8
. Perfect binding production process 4. gluing; 5. cover feeding;
6. delivery
(courtesy of BTI-Hellas SA - Heidelberg Finishing Systems)
Figure 9
. Production chain for saddle stitching binding: collating, cover
feeding, stitching, trimming, delivery
(courtesy of BTI-Hellas SA - Heidelberg Finishing Systems)
There are two main procedures in development of finishing systems for
digital printing:
- 1. ON LINE
This processis comparable with the processing of offset printed sheets
by small size traditional printing machines. They include the following machines:
- Folding machines
- Gathering – collating machines – vertical or horizontal system
- Stand – alone binding machines
- Cutting machines – trimming machines
- 2. ON LINE
- More complex systems in different workflows.
- Combined techniques of binding.
- Automatic collating.
- Sophisticated on line-trimming.
The basic characteristics of finishing and binding systems have been
developed in order to adapt at the specific requirements of the digital printing
machines [PER 99].
These characteristics can be defined as follows:
- Folding and collating production processes had to be integrated into the digital printing machines.
- A new range of stand-alone machines have been manufactured with smaller dimensions.
- Saddle stitching binding is also integrated with the digital printing systems.
- Perfect binding is combined on line with digital printing systems.
Figure 10
. Drawing of a collating and saddle-stitching finishing system
that is integrated into a digital printing machine
(courtesy of XEROX HELLAS SA)
Figure 11
. Presentation of different types of binding that is integrated
on digital printing systems that print loose sheets of paper at the A4 dimension
(courtesy of HEROX HELLAS SA)
Figure 12
. A vertical collating system for loose sheets gathering
(courtesy of Duplo International Ltd)
Figure 13
. Small folding machine for leaflets
(courtesy of BTI-Hellas SA - Heidelberg Finishing Systems-Stahl GmbH)
Figure 14
. Cutting and trimming machine for paper with maximum dimensions
of 36x52cm
(courtesy of BTI-Hellas SA - Heidelberg Finishing Systems-POLAR GmbH)
Figure 15
. Perfect binding machine for off-line book binding
(courtesy of of BTI-Hellas SA - Heidelberg Finishing Systems)
Structure of the workflow for digital printing and finishing:
The workflow in digital printing and finishing is deternined by the
different printing systems that are in use today.
Almost the half of the pure digital printing systems print sheets of
paper mostly in the dimensions of A4 or A3. The hybrid machines (where data
are transferred directly to the printing units but printing is done with normal
inking systems), print bigger sheets (ie 50x70cm). Finally, there are machines
that print rolls of paper at a maximum width of 50 cm. The finishing systems
are classified according to the characteristics of each machine or group of
machines. This classification is presented at the
Figure 16
that follows:
Figure 16
. Workflow production for digital printing
and finishing systems
The different workflows of finishing systems can be classified as follows:
- Brochure finishing I for A4 and A5 documents with saddle-stitching binding ( Figure 17).
- Brochure finishing II for bigger number of documents with saddle-stitching binding ( Figure 18).
- Book finishing with perfect binding system ( Figure 19).
Figure 17
. Finishing production workflow for A4 and
A5 brochures
(courtesy of XEROX HELLAS SA - XEROX INC)
Figure 18
. Finishing workflow for brochures bound
with saddle-stitching binding process
(courtesy of XEROX HELLAS SA - XEROX Document Technology Center, Walldorf,
Germany)
Figure 19
. Finishing workflow of perfect binding for
digitally printed books
(courtesy of XEROX HELLAS SA- XEROX Inc)
Further development of finishing systems and benefits for digital printing
Finishing and binding systems have been developed very fast in order
to cover the demand for production of digitally printed and finished documents.
This development took place by staying to the «shadow» or rather
behind the digital printing systems which were –and still are- much
more attractive and impressive.
In a short period of time finishing and binding systems have been developed
and in order to give to the digital printing systems the possibility to complete
the production process of printed documents.
Digital printing combined with finishing systems is today into the position
to produce final printed documents that look and function much more professional
as from the near past.
Finishing and Binding systems give to the digital printing machines
the necessary and required efficiency to bring to the publishing market complete
solutions of production and make this new printing and imaging process able
to enter more dynamically into the printed media market.
Conclusion:
The digital printing systems and machines should never been widely accepted
if they had been stayed only on the printing of loose sheets of paper.
As systems that PRINT on PAPER they have to implement the main task
of a printed document. To look and function exactly as the traditionally printed
and finished documents and products.
Finishing systems implement the main advantages of digital printing
versus the traditionally printed documents, such as the considerable minimising
of production time especially from the complete files from pre-press to the
final product.
As a consequence,he added value of digital printing is considerably
increased when a finished product is delivered.
It is necessary to consider that the quality of digitally printed documents
is defined and evaluated not only from printing but also (and even more) by
the overall quality of the appearance of the final product.
Suppliers, sales people and customers are mostly concentrated on printing
quality and ignore at most cases the factor of the overall quality as it is
determined before.
This has to change and all of us are responsible for keeping the correct
procedures on what a digitally printed document is and which its characteristics
must be.
XML is a very interesting new approach for cross-media publishing. That
means that we can process a document that can be published either into the
Internet or into a Multimedia application AND on PAPER.
- PAPER MEANS PRINTED MEDIA
- (ALMOST EVERYTHING) PRINTED MEDIA NEEDS TO BE COMPLETED AS A FINISHED PRODUCT!
That is the importance of processes that we must not ignore if we want
to have a complete view on the communication market.
Finishing and binding this will exist even when traditional offset will
be totally replaced by digital printing (Well I hope that will not happen
in the next 20 years!)
THEREFORE WE NEED FINISHING TECHNOLOGIES BECAUSE THEY TURN DIGITALLY
PRINTED DOCUMENTS TO LOOK, FUNCTION AND BE PROFESSIONAL.
Acknowledgements
I would like to thank Prof. Nils Enlund for his help for the orientation
of this paper towards the direction that Graphic Arts Media and Publishing
is NOT only computers and data but also machines, production processes and
final products on Paper.
Bibliography