Web Control System for Printing Press Waste Reduction
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Solution Overview
Problem
The high cost of printing substrates, such as paper webs, is exacerbated by material waste during startup, job changes, and component replacements in printing presses, as existing technologies do not efficiently manage web material usage.
Innovation Solution
A printing press system that includes a controller to record the number of printed images, rewind the web based on image count, and control ink removal and throw-off mechanisms to minimize substrate waste by printing additional images over previous ones on unprinted areas, optimizing web motion and ink usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the web is fed continuously through the printing press during startup and job changes, then the press can operate without stopping, but a large amount of web material is wasted
Solution Approach 1:
The system prints test images on the web, inspects them, and if they are unacceptable, rewinds the web to a previous position to print additional test images. This recovers the web material that would otherwise be discarded by rewinding and reusing it for further testing, thereby reducing overall waste while maintaining operational continuity.
Solution Approach 2:
The inspection unit continuously monitors printed images and provides feedback to the controller. Based on this feedback, the controller decides whether to rewind and reprint or continue feeding the web. This closed-loop control optimizes web usage by only proceeding when quality standards are met, minimizing waste without compromising productivity.
2Loss of substance
If the web is rewound and reprinted multiple times during startup to achieve acceptable print quality, then material waste is reduced, but the process time increases
Solution Approach 1:
The system performs preliminary printing of test images and immediate inspection during the startup phase. By detecting issues early and triggering rewinds only when necessary, the system avoids unnecessary time consumption while still achieving acceptable print quality. The preliminary action of printing and inspecting allows for efficient decision-making about whether to rewind.
Solution Approach 2:
The web handling system dynamically adjusts between feeding forward and rewinding based on real-time inspection results. The controller optimizes the sequence of operations, determining the most time-efficient path to acceptable quality by dynamically deciding when to rewind and when to continue feeding, thereby minimizing both waste and time loss.
3Stability of the object's composition
If ink removal devices continuously contact the printing cylinders, then ink distribution remains consistent, but substrate waste increases during inspection and adjustments
Solution Approach 1:
The ink removal devices operate periodically rather than continuously. They contact the printing cylinders at specific intervals during the web feeding process, particularly during acceptable print quality phases. This periodic operation maintains ink distribution consistency when needed while reducing substrate waste during inspection and adjustment periods when continuous contact would be unnecessary.
Solution Approach 2:
The system preemptively stops ink removal device contact with the printing cylinders when inspection indicates that adjustments are needed or when the web is being rewound for retesting. This preliminary anti-action prevents unnecessary ink application and substrate consumption during phases when printing is not producing acceptable results, thereby reducing waste while maintaining ink consistency during productive printing phases.
Data Source
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AI summary
A method is provided which reduces substrate waste while adjusting the press parameters to obtain a satisfactory image. The method includes the steps of: supplying a web (12) to a printing press (100); printing a plurality of first images on the web at corresponding printing positions; inspecting one of the first images on the web (12); rewinding the web to one of the printing positions; and printing a further image over one of the first images on the web. A printing press (100) is also provided which is configured and arranged to print in accordance with the method.