Progress in print prefection

12 May 2011



Ensuring that printed output is perfect in the early stages of production can be achieved with the help of technology and can lead to less waste. MJ Deschamps reports.


In print production, inspection has traditionally taken place at the very end of the converting chain, once an entire batch of processed material has come off the presses. Errors are commonly found at the final stage, and because of this, printers have tended to produce a surplus of printed material to deal with the inevitable erroneous products. This approach has created a lot of waste for printers in the past, however, which is why companies have recently been taking a different approach when it comes to inspection, to minimise waste and enhance output efficiency.

Jim Wright, North America Business Development Manager for Print Inspection Systems for Erhardt+Leimer, says recent years have seen the expansion of print inspection, from prepress all the way through to finishing.

“Printing is the front end process of converting, so if you want a good product to come out of converting you at least need a good product going out of printing into converting,” he says. “Historically, print inspection was done after printing but by then the impact of commercially unacceptable product had already negatively impacted operating margins.”

John Cusack, Product Manager at QuadTech Ireland, agrees that the key development right now is the movement away from a purely reactionary print inspection system. Today, the system needs to do more than just identify variations in the process. “It needs to verify the process is correct from the beginning,” he says.

He observes that add-on tools that use prepress files to verify content prior to full production, or continually verify features such as barcodes, are currently being sought by printers. To address this need, he points to QuadTech’s recent launch of PDF Verification, a software-based product designed to verify press setups. The company will also soon be rolling out a feature to verify barcodes as they are printed. “100% inspection is becoming very much a standard part of the press,” says Mr Cusack.

QuadTech recently developed the Autotron 2600, to be an integrated, flexible and cost-efficient tool for minimising waste and improving print quality across packaging and decorative printing applications. Its specialised solid-state scanning heads are designed to detect a wide range of pale and low-contrast marks, including detectable varnishes, lacquers, UV inks, and cold seals.

According to the company, the ‘unique’ control algorithms automatically adapt the system to changing press conditions, ensuring optimum control during all phases of press operation.

German company Nikka Research Deutschland specialises in providing high-tech automation, inspection and measurement solutions for the labelling and packaging printing industries. Its Alis and Odri systems are widely used in cosmetics, pharmaceutical, packaging, beverage and food product printing.

To distinguish non-significant process fluctuations from relevant defects in line art, halftone images and text, Nikka’s systems employ a rich set of inspection algorithms. Print inspection relies on the comparison of a reference image, and can detect a variety of print defects such as spots, missing print, registration and colour deviation. Nikka has also moved towards linking the inspection system to prepress, acquiring the reference from a PDF file.

Advanced Vision Technology (AVT) is one of the leading worldwide developers and manufacturers of automatic inspection systems for web applications in the packaging, labels, folding cartons and commercial printing sectors. Its PrintVision/Helios II is an advanced 100% automatic inspection system for label and narrow web printing that in addition delivers quality assurance capabilities and inspection throughout the entire print production workflow, from setup through printing to finishing.

The PV/Helios system II identifies defects on labels as soon as they occur, thereby lowering the level of waste, and improving quality, says the company. Using sophisticated algorithms, the system is said to be able to detect every type of printing or finishing fault: colour mis-registers, colour variations, hazing, misprints, text defects, spots, splashes, diecut problems, barcode problems, missing labels, and many other print issues.

Heidelberg also employs an early warning system in its Prinect Inspection Control technology, which identifies and reports print errors before they can generate any follow-up costs. As a consequence, it puts an end to costly manual quality assurance measures or expensive reprinting of the whole run due to minor printing errors, states the company.

The label inspection system from fellow German company Vision Experts is another complete inline system for high speed print inspection. It automatically inspects labels for all kinds of packaging, such as bottles, cartons and cans. With continuous process monitoring, printing flaws are detected the moment they occur and the machine operator is able to take appropriate corrective action.

This enables completed rolls to be processed more quickly in the subsequent packaging and monitoring process. As a part of the winder, Vision Experts’ inspection systems ensure that products are completely free of flaws. Even the smallest of text errors and dirt spots are detected and cause the winder to stop, states the company.

Sometimes, flaws on labels can be especially difficult to detect, particularly when they are embossed or use a special kind of paper. Because of this, UK print inspection company TecScan has recently developed an advanced system for in-line inspection and quality monitoring of embossed holograms in production.

Called AVIS-H, this system is designed to inspect metallised and translucent holograms. It is claimed to be capable of inspecting at full press speed at any stage of production, such as after embossing, metallising, printing or de-metallising. It provides a real-time static image of the hologram for inspection with optical zoom capabilities of up to 10 times resolution. There is also an option to include automatic defect detection, which works by storing a perfect image and comparing it with the real-time image.

Besides companies looking for print inspection systems that are integrated into the printing process, Quadtech’s John Cusack notes that printers are increasingly looking for consolidation of products onto a single platform or suite of products from vendors. “This allows the printer to have fewer points of contact for auxiliary equipment, makes it easier to cross-skill operators, and creates efficiencies that can reduce the number of operators required to run the press,” he says. In this respect, QuadTech recently combined its 100% inspection, web viewer and colour measurement products.

Mr Cusack believes that the quest towards such high performance inspection comes from the fact that as inspection has become more commonplace, printers have become very savvy when it comes to inspection system performance. “They understand the camera technology, the differences in lighting solutions and how inspection algorithms work, so they demand performance and can readily measure that performance,” he affirms.“For any company to be profitable in an increasingly competitive global marketplace it must have a systematic approach to analysing the flow of information and materials within its operations to eliminate waste and increase productivity.”

Erhardt+Leimer’s Jim Wright adds that while print label errors have never been seen as acceptable in the converting process, they are now completely avoidable with the latest technological advances.

“I don't think there was ever a time where there was room for labelling errors,” he argues. “However, the technology, techniques and procedures to prevent and eliminate them were not always available, and as a result, errors got out. Now that the technology and techniques exist and customers of converters know they do, there is very little room for errors.”


The Nyscan multi-camera system from Erhardt+Leimer uses both a high-resolution black/white camera and a 3-chip high performance colour camera to inspect webs with a width of up to 1,200mm. Another advantage is the application of the fully integrated TubeLNyscan Bleed-out is one example of a defect that can lead to printed work being rejected. This type of defect can be identified by QuadTech's inspection/colour measurement equipment when the press is running at high speed. Bleed-out QuadTech's spectral device for packaging and narrow-web applications is the SpectralCam, which is integrated into the company's inspection system. QuadTech

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AVT
Erhardt & Leimer
Heidelberg
Nikka
Quadtech
Tecscan
Vision Experts

Bleed-out Bleed-out
Nyscan Nyscan
QuadTech QuadTech


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