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50 years of electromechanical engraving
This truly revolutionary development ushered in the industrial production of gravure cylinders for illustration, decorative and packaging printing. As a »direct, singlestage, semi-autotypical production method«, electromechanical engraving subsequently replaced the production methods of conventional (cells with variable depth) and autotypical (cells with variable area) cylinder etching that had dominated up to this point. The complex manufacturing process was highly manual and featured multiple stages. Yet on closer inspection, gravure forme production at that time actually always involved the conventional method. As a result of their dome-shaped cells of variable depth, the cylinders produced using this process were characterized during the production run by superb colour brilliance, colour saturation, and a certain »threedimensionality« that is today often still unequalled. The production and time- and personnel-intensive outlay that needed to be invested in this system is illustrated by the following operations for manufacturing a conventional gravure forme: ● Screen and contone copy of the pigment paper; ● Manual cleaning and degreasing of the Copper surface of the cylinder;
The birth of the HelioKlischograph K190
According to OTTO M. LILIEN, specialist historian and former Research Director of the Axel Springer Publishing Group in Hamburg/D, a meeting took place in October 1959 in the office of Dr WALTER MATUSCHKE (the then Technical Director of Axel Springer) with Dr RUDOLF HELL that was actually intended as a discussion about Dr HELL's, as yet, embryonic Colograph colour scanner. On this occasion, Dr MATUSCHKE noted that »you make such successful colour Klischograph systems for manufacturing plates. Please do something like that for gravure cylinders«. Dr HELL took with him a small impression cylinder from the Isar gravure test printing press located in Axel Springer's laboratory to perform a few tests. These led at the beginning of 1960 to print proofing of the first cylinder engraved on a lathe with a standard Klischograph engraving head. The original was scanned using a VarioKlischograph scanning head on a second lathe that was mechanically connected to ensure perfect synchrony. This heralded the birth of the first HelioKlischograph K190 engraver from Dr.-Ing. Rudolf Hell KG, which was unveiled at DRUPA 1962.
Left: Hell experimental laboratory in 1959 – first test setup for electromechanical engraving. Right: Inventor of electromechanical engraving – Dr Rudolf Hell.
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Manual application of the pigment paper onto the cylinder surface; ● Subsequent development in 40 °C water bath to form a graduated etched relief (rinsing out the unhardened gelatine); ● Covering with asphalt coating/ masking all non-image areas; ● Etching with iron (III) chloride; ● Coating removal, cylinder cleaning, and measurement of cell depth; ● Touching up the circumferential and lateral seams; ● Copper retouching (tonal value correction through post-etching); ● Print proofing the gravure forme.
From multiple stages to a single process
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The invention by Dr Rudolf Hell marked the start of industrial and thus standardized gravure forme production ANSGAR WESSENDORF
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Functional principle of the K193
Nothing has changed in the functional principle of electromechanical engraving in the last 50 years. The improved successor to the K190 was the HelioKlischograph K193 with its two equally large cylinders that were either rigidly connected to each other (K493 model) or were located in separate units with a synchronous drive (K193 model). Both cylinders rotated at the same speed. The original cylinder bore the scanning copy (generally a contone/text combination) and the Copper surface of the gravure cylinder was engraved using an electromechanically controlled diamond stylus. Scanning was mainly performed by a light source and two photomultipliers that together with an optical lens and related electronics were combined in an optical head. The cylinders rotated at a constant circumferential speed and the photomultipliers, which received the light reflected from the original, transmitted the density values of the rotating original as electrical signals. The optical head moved along the original cylinder with a defined rate of feed to scan the original in a helical form. At the same time, the impression cylinder was engraved by a diamond stylus operated by an electromagnetic system and proSource: BORIS FUCHS and CHRISTIAN ONNASCH, »Dr. Rudolf Hell – Der JahrhundertIngenieur im Spiegelbild des Zeitgeschehens«, Heidelberg/D 2005.
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FLEXO & GRAVURE ASIA 1-2010 © by G&K TechMedia GmbH · D-79261 Gutach · www.flexo-gravure-asia.com
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C O M PA N Y R E P O RT
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The first engraver was the HelioKlischograph K190, unveiled at DRUPA in 1962.
duced a constantly vibrating movement. The cylinder surface moved constantly during this process. Every time the stylus pierced this (4000 times a second = 4 kHz), it removed a chip from the surface. The deeper the stylus penetrated the cylinder skin, the larger the resulting cells. The penetration depth was controlled by the signals from the photomultipliers using an operational amplifier, corresponding to the reflection density, as described above. Electromechanical engraving of gravure cylinders required optics, electronics, and mechanical elements to work in tandem, as is generally the case for electronic image reproduction. The cells took the form of foursided pyramids with their opening at the top. In the deep image tones, their edges almost coincided, leaving only a narrow cell wall between them. In the light sections, on the other hand, the cell wall became increasingly wider and ultimately there were only very small cells to be seen in the original surface of the printing forme in the completely light tones. In the case of conventionally etched cylinders with cells of variable depth but uniform area, the lightest tones could be lost during printing as a result of wear to the cylinder surface. However, most of the blade-bearing surface of the electronically engraved cylinder occurred in the light sections with a cell depth of around 7 µm. Wear caused by the blade therefore had scarcely any impact. The HelioKlischograph K193 (unveiled in 1963) engraved gravure cylinders on a 1:1 scale. It was possible to process the originals as reflective images positively or negatively, in a right-reading or laterally reversed format (only laterally reversed on the K493 system model). On a white cylinder, positive or negative contone films could also be scanned directly in reflective mode. Numerous quick and easy methods for creating a scanning copy from the original were thus available to the photographic department. Text could either be copied in or superimposed in the form of transparent masks. However, the originals had to be the same as each other in terms of initial density, density range, and gradation. No ○
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screen copy work was required, as the engraver itself performed the screening. The scanning unit and engraving system were moved along the originals and impression cylinder in the axial direction. A certain distance was travelled after each cylinder rotation. The screen cells were engraved in such a way that every second row of cells was offset to the first. As a result, the screen was at a 45° angle to the axial direction, as was customary for single-colour printing. With multicolour printing, screen angling was necessary to prevent colour shift and moiré. This was achieved by changing the crossfeed to a circumferential speed ratio by using a further step switch at the switch insert/control centre. Ultimately, this technical improvement paved the way for the four classic Hell screen angles 0, 2, 3, and 4. Either a 60 l/cm (152 lpi) or 70 l/cm (178 lpi) screen could be selected when purchasing a K193. The ability to engrave seamless images in the axial and circumferential directions was a crucial development in packaging printing. In particular, alternate scanning solved the difficult problem of seamless engraving in the circumferential direction. This involved alternately scanning the two partial originals using two scanning heads, with each partial original covering somewhat more than half of the scanning cylinder.
while the scale change option also meant that 1:1 scanning originals were no longer necessary. The step/ repeat function enabled the individual repeats to be engraved again and again on the impression cylinder in circumferential and axial directions. This engraver also allowed engraving with various gradations for packaging and decorative printing. The 201 model was a single-bed solution (scanning and impression cylinders on one machine bed), whereas the scanner and engraver were separate on the 202 model (as with the K193). As well as illustration gravure, the 202 model is also still widely used today to manufacture very wide decorative gravure cylinders. ● 3rd generation. Electromechanical engraving was controlled in the 1980s using a process computer with the K200 Helioklischograph versions and upwards and the K301, 302, and 303. The operator keyed in the relevant parameters and commands for engraving on the Klischograph and these were checked for plausibility by the software and saved onto floppy disk. Subsequently, this job preparation
The HelioKlischograph K193 unveiled in 1963 engraved gravure cylinders on a 1:1 scale. The originals could be processed as reflective images positively or negatively, in a right-reading or laterally reversed format.
The next generations ● 2nd generation. At the start of the 1970s, Hell launched the K200, the first digital HelioKlischograph. It was possible to buffer the digital scanning signal (microprocessor), ○
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FLEXO & GRAVURE ASIA 1-2010 © by G&K TechMedia GmbH · D-79261 Gutach · www.flexo-gravure-asia.com
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work was no longer performed directly on the engraver but on the HelioSet job preparation station, which cut makeready times significantly. The required gradation table was loaded from the floppy disk prior to engraving. Using a special program, users themselves were able to create a virtually unlimited number of gradations, enabling the parameters of the engraved gravure formes to be adapted to the respective production conditions (inks, printing stock, print proofing behaviour, etc.). The »fast crossfeed« function also allowed the carriages of the scanning and engraving units to be moved in both directions at high speed, thereby cutting engraving times considerably. Introducing the O/G conversion scanning head made it possible to process originals created for offset printing (O) with screening unsuitable for gravure (G). The screened film was descreened by the scanning mode, as though the original were a contone film. This new technical possibility was of interest first and foremost because production of contone films was always complex, time-consuming, and problematic. ● 4th generation. The start of the 1990s saw fulfilment of the long sought-after goal of doing away with the scanning procedure altogether and controlling the engraving heads of the K304, 305, and 306 from the digital data storage unit of the full-page data processing system. The engraving data was created in a closed data format on electronic image processing systems from Hell, Crosfield or Scitex. ● 5th generation. The period from ○
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the end of the 1990s until around 2002 was marked by further farreaching developments, which included the K405 (Sprint) for manufacturing packaging and decorative cylinders. The addition of Sprint highlighted the fact that the engraving speed, which had been 4 kHz for over 40 years, almost doubled to 7.5 kHz. The K500, a fully automatic version with robot loading of gravure formes, was also added to the range. Digital image processing was performed on Mac and PC computers, TIFF workflow/TIFF direct engraving was launched and hard and soft proofing helped prevent errors and boost quality in gravure forme production. Open data formats ensured enhanced processing of text (PostScript) and images (TIFF) and also simplified data exchange. This also visibly accelerated the gravure forme production process.
Early in the 1970s, Hell launched the K200, the first digital HelioKlischograph. On the right, the scanning unit (two scanning heads and white scanning cylinder), on the left, the engraving unit (two engraving systems and a Copper gravure cylinder to be engraved).
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1959 1962 1965 1969 1974 1980 1981 1983 1985
April 1, 2002 can be regarded as a milestone, not only in the history of Hell Gravure Systems but also for modern gravure forme production as a whole. On that day, Heidelberger Druckmaschinen AG sold its stock to Dr SIEGFRIED BEISSWENGER (the then CEO of Hell Gravure Systems) and MAX RID (owner of Kaspar Walter). Intensive and productive collaboration developed between the two companies across the entire value-added chain in manufacturing gravure formes (electroplating, surface treatment, engraving, quality control) and is something which continues to this day. This resulted in fresh impetus that raised the bar in fully automatic and standardized inline production through integrating machines and systems. The result of these joint development efforts was the fully automatic production line AutoCon, which is successfully used today throughout the world with virtually no personnel requirements in countless gravure print shops and engraving companies. The major goal of fully automatic industrial production of gravure cylinders was therefore achieved.
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2006 2007 2008
The latest generation
»All good things come in threes« – ○
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First gravure reproduction based on electromechanical engraving HelioKlischograph K190 – premiere of the HelioKlischograph HelioKlischograph K193 – separate scanning and engraving beds HelioKlischograph K493 HelioKlischograph K200 with digital electronics HelioKlischograph K201/202 with process computer Offset/gravure conversion HelioKlischograph K301, K302, K303 Electron beam engraving presented to the trade HDP – Helio Data Processing HelioKlischograph K304 HelioSet job preparation workstation HelioKlischograph K305, K306 HelioScan CN 420 – redigitization of film originals Gipsy – Gravure Image Processing System HelioForm – printing form assembly for publication HelioRip – PostScript connection for gravure output HelioKlischograph K405/K406 HelioCom – cylinder layout workstation for packaging TIFF direct engraving and job ticket workflow HelioFormproof – cylinder layout proofing system HelioSprint – 8 kHz high-performance engraving system CellGuard – camera system for packaging HelioKlischograph K500 Gipsy NT – real-time data processing on a PC platform CellGuard – camera system for publication AutoSpacer – measuring system for axial register HandyCam – measuring camera with online link HelioKlischograph Compact HelioKlischograph K6 SprintEasy – camera-based measuring station for engraving heads BookletProof – engraving job simulation High Quality Hinting – quality-optimized gravure output TIFF Upgrade Kit – modernization option for the HelioKlischograph Hell Security Engraving – Intaglio engravings XtremeEngraving – high-resolution engraving CellGuard III – volume-oriented cutting GravureCheck – final quality check AutoCon – fully automated packaging production line Cellaxy – direct laser for chrome and Copper StatusManager – online production monitoring WebApproval – online approval to print FormManager – automated form layout creation CellEye – repeat-accurate cylinder engraving HelioKlischograph K5 HelioKlischograph K50 HelioKlischograph K500 Twain HelioSprint III (12 KHz)
1990
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Electromechanical engraving – a timeline
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that's probably what they were thinking at Hell Gravure Systems when it presented the three versions of the HelioKlischograph in 2008. The K5 is the compact entry-level model, equipped with an 8 kHz engraving system and manual control elements. Depending on the
A significant day
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FLEXO & GRAVURE ASIA 1-2010 © by G&K TechMedia GmbH · D-79261 Gutach · www.flexo-gravure-asia.com
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C O M PA N Y R E P O RT
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Far left: The K304 was able to engrave two gravure cylinders simultaneously in the Twin version.
engraving system, it operates in a screen range of 24–210 l/cm (60– 533 lpi) with an engraving depth up to 110 µm with either rapid helical or precise polar line engraving. The software's features include logging engraving parameters, engraving TIFF complete formes, and fast crossfeed. This model is enjoying great success, particularly in the Asian market. The next level up is the automatic K50, which also has an 8 kHz engraving head and is equipped with all functions (CellEye, XtremeEngraving, High Quality Hinting, SprintEasy etc). The system takes the job data from the job ticket and engraves from standard TIFF data. It also has two feed speeds for setup and boasts patented sequential engraving. Operation is performed via a touchscreen or keyboard. The engraver has »one-button operation«, where only loading and unloading the gravure cylinder are manual. The engraving process (including the cutting procedure) is fully automatic. The K500 is the most successful engraver in the history of Hell. Over 600 systems have been sold since it was launched onto the market in 1999. Since then, the fully automatic HelioKlischograph, which can be integrated into automatic lines, has continued to set new standards in gravure forme production when it comes to production speed and quality. In this regard, the K500 G3 Twain (multi-head engraving) unveiled at DRUPA 2008 is the most state-of-the-art technology that electromechanical engraving currently has to offer. The entire cylinder engraving process runs fully automatically without virtually any personnel requirements. At the heart of the Twain system are two HelioSprint III engraving systems of 2 x 12 kHz that move independently of each other, with the linear drive (instead of a spindle drive) enabling fast and highly precise positioning. The system automatically divides the packaging ○
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image for cylinder engraving between the two engraving channels. The automatic CellEye cutting process integrated into the machine, which is based on the principle of volume measurement, factors in the Copper hardness and the actual angle of the engraving diamond stylus, and the SprintEasy measuring station for measuring the cutting angle ensure absolutely identical repeats. For optimum rounding of contours or engraving extremely fine text and characters, Hell developed the Helio-Xtreme 32 broadband engraving system. Equipped with two engraving systems of this type, the K500 G3 Twain performs XtremeEngraving at up to 24 kHz (2 x 12 kHz). This innovation is therefore three times faster than its predecessor, the HelioXtreme 22. This version of the K500 has almost the same productivity as two K500 NT engravers (spindle drive; one engraving head).
Left: Introducing the O/G conversion scanning head made it possible to process originals created for offset printing (O) with screening unsuitable for gravure (G).
tion of gravure cylinders. The number of HelioKlischograph systems installed throughout the world, which has now reached over 2000, provides impressive confirmation that this is a view shared by the market. ➜ www.hell-gravure-systems.com
Interesting facts and figures 1972 1984 1984 1990 1996 1997 1997
Summary
In the course of its 50-year history, electromechanical engraving has developed into the leading process for high-quality production of gravure cylinders. Like no other process, it has repeatedly succeeded in adapting to changes and varied market requirements in packaging and decorative gravure through innovative solutions. The following points are of crucial importance to ensure continued success: ● Fully-developed and tried-andtested technology. ● Rapid availability of the gravure forme (short jobs) at relatively low cost. ● Intuitive functional features. ● Exceptionally high level of automation. ● High fidelity even for repeat jobs. ● Relatively low investment compared to other methods. In conclusion, it can be said that electromechanical engraving has played a key role in the industrial and therefore standardized produc○
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100th HelioKlischograph (Gruner + Jahr, Itzehoe/D) 250th HelioKlischograph In Europe, 95% of all gravure cylinders are engraved 600th HelioKlischograph 800th HelioKlischograph Founding of Hell Gravure Systems GmbH Last Western European gravure print shop discontinues etching 100th HelioKlischograph K500 100th birthday of Dr RUDOLF HELL Management buyout of Hell Gravure Systems GmbH 41 HelioKlischograph K500 units for China 1000th HelioSprint engraving system 222nd HelioKlischograph K500 7000th engraving head 300th HelioKlischograph K500 600th HelioKlischograph K500 Heliograph Holding
2001 2001 2002 2002 2002 2003 2003 2004 2008 2009
A momentous history RUDOLF HELL, the inventor of electromechanical engraving for gravure cylinder production, founded Dr.-Ing. Rudolf Hell KG in Kiel/ D in 1947. The Siemens electronics group acquired a shareholding in this company in 1971. Following the merger with Linotype AG in 1990, Dr.-Ing. Rudolf Hell GmbH was renamed Linotype-Hell AG. In 1997, Heidelberger Druckmaschinen AG took over the company, which as Hell Gravure Systems GmbH was managed as an independent entity. In 2002, Hell Gravure Systems was sold to Dr SIEGFRIED BEISSWENGER (the then CEO) and MAX RID (owner of Kaspar Walter). Since 2009, the Kiel/D-based company has been owned by Heliograph Holding. Besides Hell Gravure Systems, this company also owns gravure supplier companies Kaspar Walter, Daetwyler Graphics, Schepers, and Bauer Logistik-Systeme. ○
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FLEXO & GRAVURE ASIA 1-2010 © by G&K TechMedia GmbH · D-79261 Gutach · www.flexo-gravure-asia.com
