Last Word - John Cusack

22 September 2014



Over the past decade, brands have used increasingly sophisticated substrates and print enhancements for their product packaging and labelling security printing. John Cusack, product manager of QuadTech, discusses the new challenges for web inspection.


So commonplace have many of the advances in materials and technology become that now they can be found on mainstream and lower cost items as well as luxury packaging and labels. At the same time, higher security items such as credit cards, gift certificates, vouchers and common financial documents include security features like holograms, UV inks and foil stamping.

The need for product security and brand protection means that these products and features need to be inspected. Inspection can take place on the press, on the finishing line, or both, depending on the nature of the decoration or security device. Given that many of the substrates are of higher than average value, the earlier in the workflow that faults can be identified, the greater the savings that can be made.

Printers and converters who can offer web inspection that identifies these faults and save their customers time and money can be at once more competitive and more profitable.

"Noise" in the inspection process is random light. Foils, metallised substrates, holograms and other print enhancements may create a serious challenge for camera-based systems. In certain circumstances, automatic inspection can be rendered virtually impossible.
However, most applications can be successfully inspected by the right system. Determining what that system is however, needs careful consideration and consultation.For example, what is needed to inspect holograms on tickets, ID cards, credit cards or other products? And, what would be the appropriate configuration to ensure the inspection parameters necessary for compliance?

First, the inspection system will ensure that a hologram has been applied. Secondly, it will verify its registration on the document and its correct orientation. It will also confirm that it is correctly applied, without folds, wrinkles or other defects. The same approach would be taken for inspecting hot or coldfoiling, coldseal application, and spot varnishes.

One of the challenges is that the security and differentiating devices used by brands and financial companies are, by definition, different to what their competitors are doing. It follows, then, that an inspection system needs to address those unique characteristics.

The result is that off-the-shelf solutions will often not meet requirements, and installation of multiple devices to cover what is required can lead to expensive over-specification and features that will never be used.

Customer focused

By listening to individual customers' requirements and designing a solution that integrates best with the workflow and the products produced, the systems can become more like platforms than off-the-shelf solutions. They are developed to be used on a wide variety of presses and finishing lines and can be mounted, modified and adjusted to meet highly specific applications.

QuadTech's SpectralCam offers a flexible platform that can be configured on a press or finishing line and equipped with lights and cameras to deliver the level of coverage the customer needs. It measures spectral response, calculates L*a*b, Delta-E, Density and Delta-Density at full press speeds.

For hologram or foil inspection, QuadTech uses proprietary LEDs to provide optimum illumination for inspection. LEDs use AC current and the cameras can tune out the regular oscillations produced, giving a clear, stable image and compensation for the resultant noise. A top light focuses a narrow beam on the web to inspect normal print. Its intensity can be adjusted to provide optimum inspection conditions for the substrate. Special lights producing a lower intensity and diffuse light are used for inspecting metallic foils or UV varnishes, while a "back light" can be used to inspect translucent and transparent materials. QuadTech's lamps are rated for 100,000 hours of use.

The intensity and focus of LEDs are high and concentrated enough to counteract the noise from the reflections from the UV cured areas, even when the inspection system is mounted close to the UV curing unit. Other sources of illumination are not as effective and can result in amplification of ambient noise.

Additionally, the inspection system's sensitivity can be independently specified from a simple "low, medium and high" to up to 50 different levels for special requirements. Particular attention can be directed to user-defined areas of the web including multiple specific targets for inspection. Today's brands require high levels of product security and integrity as well as print quality. Printers and converters need to compete, and offering the assurance of high quality, defect-free print provides a significant advantage. ?

The author's views on this page may not be shared by this publication.

www.quadtech.com



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