When Pre-Press, Printing, and Spectral Inline Color Measurement Work Hand in Hand
Achieving the colors specified by the customer quickly, reliably, and conveniently, and doing so while keeping production reliably stable – the close cooperation between BST eltromat International and the pre-press specialist and printing plate manufacturer COE (Carl Ostermann Erben GmbH) now makes this possible for manufacturers of flexible packaging. For this, an easy-to-use user interface between COE’s pre-press workflow and BST eltromat’s solution for inline spectral color measurement plays a key role.
As for other print methods, close coordination between pre-press and printing is also the key factor for significantly shorted setup times on the web printing presses and for more convenience for the machine operator in the manufacturing of flexible packaging. The simplified work and the elimination of the opportunity for defects in “manual input” already suggest that the job data that is used in pre-press for the production of the printing plates flows directly into the quality assurance systems for the printing presses. In addition, start-up waste is significantly reduced if packaging printers set the correct individual inspection parameters during machine setup from the outset. The more often an job change occurs in day-to-day work, the more positive the impact of these factors.
However, the transfer of job-specific data from pre-press into the inspection systems alone does not guarantee that the packaging printers will later work with stable color values and thus that the branded companies’ specifications will be maintained over the course of the entire print production process. This is where inline spectral color measurement comes into play. If this is wirelessly connected with pre-press and printing, the manufacturer gets a level of production reliability hitherto unknown in flexible packaging.
Production Fully Under Control
With this goal in mind, COE as a pre-press specialist and printing plate manufacturer and BST eltromat International as a producer of innovative solutions for quality control in web printing developed an interface through which production data can flow directly from pre-press into the iPQ-Spectral inline spectral color measurement solution.
The process is thus broadly redefined: As before, pre-press gathers all of the relevant production data and prepares it typographically for web printing. The data is then – unlike in the past – read directly into the inline spectral color measurement system integrated into the machine. The system is then in a position to monitor whether the color values specified by the branded companies are solidly achieved during the entire production process. Spectral color measurement is thus moved from the measuring table into the web printing press. Notably, this is possible because iPQ-Spectral was developed in cooperation with X-Rite, the market leader for offline measurement systems, and thus has ideal comparability with offline handheld units thanks to the XRGA standards.
The benefits are clear, when the color results produced on the substrates are continually measured at selected color points and reported to the machine control system. The quality control system sounds the alarm if there is the slightest deviation from the reference values. The machine operator can intervene in the process immediately and correct the settings via the operating monitor – before waste occurs. This proves to be more than just a crucial cost benefit. In fact, complaints and arguments with customers are essentially being eliminated thanks to inline spectral color measurement.
As packaging printers document the color values measured in logs, they can also easily prove that they have achieved their client’s specifications throughout the course of production or have worked within the tolerances. Color measurement now occurs continually during the entire print run and is no longer limited to a few measurements that are typically only taken after a roll change. As a result, the database that the measurement log draws on is significantly more extensive. Generally speaking, the integration of inline spectral color measurement sends a signal to customers that we do everything technically possible today in order to manufacture their packaging to the highest quality level. Communication between the packaging manufacturer and branded company is consequently raised to a new level. And it’s ultimately also simplified.
Significantly Increased Convenience for Machine Operators
Above all, however, workplace convenience is increasing once again for the machine operators with inline spectral color measurement. They no longer have to work with handheld units but rather get all the information about color values displayed automatically on their operating monitors. Thus, they always have an overview of the results achieved during the entire production process. If adjustments to the setting parameters are required because colors threaten to run outside the tolerances, the machine operators immediately see the results of the fine adjustments that they make. Gone are the days when they had to experiment and explain themselves to their supervisors for the waste that might have been produced.
Since they no longer have to configure the quality control system by hand, they also save a significant amount of time that they can use for other tasks. Added to this, input defects are generally eliminated in comparison with manual setup.
Yet another aspect: Inline spectral color measurement delivers objective and transparent measurement results. Printers can optimize their production processes in a targeted manner and increase the competitiveness of their printing plant. From the point of view of the printing press operator, too, everything seems to point in favor of integrating such a quality control tool into the production process.
Ultimately, packaging manufacturers are able to make significantly better use of the productivity of their printing presses. Because, thanks to inline spectral color measurement, they can avoid interruptions in production and thus unnecessary idle periods. And since deviations from the reference values can be detected and corrected in good time, the printing presses produce more saleable products and less waste. These are all crucial cost benefits.
The Know-How Is Based in Pre-Press
In the production of flexible packaging, pre-press with its know-how regarding the generation of data is the ideal partner to inline spectral measurement. More than anyone else, the pre-press experts have the knowledge of at which positions on the flexible packaging the printed colors need to be spectrally measured in order to reliably meet the customer’s specifications. That’s why pre-press should also have the task of defining the measurement points for the critical areas. The pre-press service provider COE not only makes printing data and printing plates available to its customers’ machine operators, but also provides the necessary data for color quality control in the form of PDF files.
Once a year, COE draws a characteristic line for each of its customers’ printing presses, taking into account the colors and substrates used in printing. If the printer’s suppliers make changes e.g. to the printing substrates or print colors, inline spectral color measurement can be used in a targeted manner to prove that possible color discrepancies in web printing can be attributed to this. Consequently, the close cooperation between pre-press, printing, and quality control also increases reliability in the production of flexible packaging at this point.
The iPQ-Spectral inline spectral measurement system works with a high resolution spectral photometer that reliably checks the color measurement positions in the printed image at web speeds of up to 1,000 m/min. This means that up to 30 measurements can be taken per second. These measurements in real time form the basis for a quick and precise indication of color deviations in the production process.
The intuitive menu structure makes the machine operator’s job easy in all process steps – from loading the orders into the job manager to monitoring production, calling up the logs for the customers, and optimizing internal processes.
When displaying the measured color values and deviations in comparison with the reference values, the machine operator has free choice between different views. iPQ-Spectral thus visualizes all values optionally in the form of series of numbers and/or as graphs with a history including the last hundred measured values. What is the trend e.g. for magenta at position 1? The machine operators simply need to press two buttons on their operating monitor and they can see the desired results. Never before has monitoring the color values in web printing been this easy.
iPQ-Spectral can optionally be augmented with a camera. The machine operator then also sees real-time, live images from the production process on their operating monitor alongside the graphs and measurement logs. The color values in production can thus be monitored even more precisely in certain cases.
In short, with the seamless integration of pre-press, printing, and inline spectral color measurement, the subject of color fidelity in the production of flexible packaging loses much of its previously scarcely avoidable unpredictability.