Job Tickets Automate Digital Engraving

Transcription

1 July 20, 1998 Job Tickets Automate Digital Engraving Job tickets for workflow automation have been used in digital engraving for packaging gravure applications for more than a year. This does away with the need to re-enter parameters in the job preparation stage and makes the entire production process far more reliable and efficient. The positive experience gathered from this process and the expertise it has created can also be applied to other printing processes. Adobe job tickets, a vendor-neutral solution Workflow automation, workflow management and job tickets - these are all words which are now part of everyday language in the prepress sector. Spurred on by a vendor-neutral solution from Adobe which uses job tickets to control the prepress workflow, prepress providers are currently falling over themselves to offer their customers solutions based on this technology. The concept which this technology employs is highly innovative: Production parameters are stored in a parameter file which accompanies the job. The format of this job ticket file is extensively standardized. This means that vendor-neutral solutions are also possible for automating the workflow. The vision is to use components from different vendors who all contribute to an automated production workflow. The pioneering role of gravure While prepress vendors are endeavoring to make this Adobe vision reality, digital engraving can already draw upon experience gathered from the use of job tickets. For more than a year, HELL Gravure Systems has been using its own self-defined job tickets for the digital engraving of gravure forms for packaging printing applications. How is it that gravure printing, a technology which has been around for some considerable time already, has found such a pioneering role? The answer is simple: While computer-to-plate technology is only just beginning to find a foothold with other printing processes, the computer-to-cylinder process used in gravure printing already has a tradition going back ten years. The next logical step, namely to bring about the complete automation of the entire production route, was very high up on the agenda in the gravure printing world. Page 1 of 6

2 Job tickets and digital engraving The example of digital engraving illustrates very clearly the benefits which job tickets can bring to workflow automation. Specialists in this field were quick to see the benefits of an engraver which works entirely automatically. It soon became apparent that the automation process would not only have to satisfy a number of machine-specific requirements, but that particular requirements would also apply to the provision of production data. For every engraving cylinder, production parameters need to be defined in advance. This is where the job ticket concept is so compelling. A concept which, applied to the entire production route, offers a whole series of additional benefits: No longer is there any need to re-enter parameters. Follow-up jobs can be reproduced exactly as all entries are archived in digital form. What is more, the process stages upstream of the engraver can now also be automated. Central job planning with the job ticket editor To understand the situation better, let us first take a look at the workflows which are affected by the job ticket. The task of digital packaging engraving is to transfer individual repro-ready repeats to gravure printing forms. The individual process stages include generation of the cylinder layout, layout proofing and engraving. A special job ticket editor records all the job parameters and generates a job ticket file for each separation. To recap, packaging printing often involves spot and special colors in addition to process colors and, consequently, six or seven separations will generally be the rule rather than the exception. Each job ticket contains all production-specific parameters required for further processing of a separation. This centralized job preparation work for multiple process stages means that repeat inputs no longer have to be made at the individual stations, this dramatically reducing the risk of operator error. All settings performed with the job ticket editor can be saved in a file and retrieved later for follow-up jobs. Each station along the production route takes the information it requires from the job ticket. What is more, however, each station also writes additional data to the job ticket, as a result of which the amount of information which the job ticket holds increases all the time. This procedure ensures that information which is not available at the first production stage can also be processed automatically during later operations. Page 2 of 6

3 It is perhaps worthwhile taking this opportunity to underline one or two facts: In theory, the level of standardization involved in predefined job tickets does run the risk of reducing flexibility. A situation may occur in digital engraving practice, for example, where a screen angle or a gradation needs to be changed immediately ahead of the engraver if the optimum result is to be achieved. Such a change is not possible using the standardized job ticket process. The HELL Gravure Systems production process has taken this practical need into account, however. The possibility does exist with the HELL Gravure Systems solution to modify job tickets at all stations, though this should naturally remain an exception in a standardized workflow. Predicting the engraving time and ink consumption as a function of layout generation Using the ready-supplied individual repeats as a basis, the entire cylinder layout, including all register and control marks, is designed under visual control on the HelioCom station. An output module specially developed for gravure output generates complete color-separated TIFF forms. Each TIFF separation is assigned to a job ticket. Prior to output, HelioCom compares the Òshould-beÓ format of the complete form as stored in the job ticket with the actual format of the layout. If any differences are discovered, an error message is automatically output. HelioCom also enters into the job ticket information on white areas, i.e. areas which are not to be engraved (and which the engraver is to travel over with fast crossfeed), and the ink coverage. This additional information can be evaluated immediately by means of the job ticket editor. This means that precise values for the anticipated engraving time and ink consumption levels are available at a very early date. Automating the engraving process The job ticket supplies the engraver, the HelioKlischograph, with all the setting values it requires. These include first and foremost the conventional engraving parameters such as engraving format, screen, screen angle and gradation. However, it is now also possible, using the AutoCut system, to automatically carry out the testcut engraving. All the parameters required for this are saved in the job ticket. The job ticket also provides information on areas which the HelioKlischograph can traverse in crossfeed mode. Other parameters in the job ticket provide information on scale changes, mirroring and special engraving sequences. Regardless of whether the HelioKlischograph is used in manual, semiautomatic or fully automatic mode, the use of job tickets will greatly facilitate operation. Page 3 of 6

4 Layout proof Òen passantó The extremely powerful HelioFormproof proofing system specially developed for packaging gravure supplies complete form color proofs of the separated TIFF files. The Designjet HP2000 or HP3000 serves as the output device. The special feature about this proofing system is that it can work fully automatically thanks to the job tickets. The HelioFormproof uses the job tickets to obtain information on the number of separations that need to be taken into account and the number of proofs that need to be printed. The HelioCom cylinder layout workstation enters additional information about CMYK simulation values into the job ticket which are used to depict the spot and special colors on the proofer. The job ticket also contains information on whether a color is transparent or opaque in print. External and internal communication One important aspect about this system is the fact that the system components need to be able to communicate if the workflow is to be automated. This is where the job ticket comes in. But what about communication to the outside? Many businesses are using production planning and control systems. These offer new possibilities for an even more efficient way of working. Why should job parameters recorded in the job entry stage not be used for automatic generation of job tickets? And, conversely, why should operating data which is already saved in the job tickets not be transferred to a superordinate system for analysis? Summary and prospects The goal of automating the engraver has been achieved convincingly through the introduction of the job ticket workflow. This solution has also completely automated the proofing system. The benefits include a reduction in the error rate, since multiple inputs are no longer required and job reproducibility is ensured through digital archiving of production parameters. The key features of this solution include the job ticket editor which functions as a type of job preparation station and the fact that what up until now have been isolated stations can now communicate and exchange information via the job ticket. The planned linkup to production planning and control systems also includes promising prospects for the future. Page 4 of 6

5 Jobticket Editor HelioCom HelioFormproof Jobticket HelioKlischograph Fig. 1: Workflow automation using job tickets is already established technology in the field of digital engraving. Fig. 2: The job ticket editor is used to define the production parameters of all processing stations in advance. Page 5 of 6

6 TIFF Data Jobticket Engraving Cylinder Fig. 3: The job ticket allows fully automatic operation of the HelioKlischograph K405 Key words: Digital engraving, computer-to-cylinder, workflow automation, job tickets Author: The author Jan Breiholdt has been employed in the packaging gravure product management section of the current-day HELL Gravure Systems GmbH for eight years. Page 6 of 6 Die HELL Gravure System GmbH is a Heidelberg company HELL Gravure Systems GmbH, Siemenswall, D Kiel Tel.: +49 (431) Contact: Susanne Hausmann Fax: +49 (431) Internet: Susanne_Hausmann@HDPP.de