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Flexo Technology


Making the case for contact web cleaning


Andy Clarke, European operations director, MAPP Q


uality and cleanliness are at the heart of cleaning webs, whether solely tidying up top surfaces or cleaning both sides of the material to ensure compatibility with onward converting and/or the intended end use.


Contact and non-contact web cleaning are both viable options for those looking to keep material spick and span. This is important regardless of the print process, as all will be impacted by the presence of dirt and debris, causing reduced overall print quality, more machine downtime and increased waste. In the case of inkjet, foreign bodies entering the digital print engine can have serious consequences on the ability to deliver high-quality prints, owing to the non-contact nature of the print process. They also risk damage and obstruction of the printheads themselves, a costly and time-consuming issue. The choice of whether to use contact or non-contact web cleaning will largely be defined by the material to be cleaned. If you’re working with sensitive materials and those with delicate surfaces,


non-contact systems can be used to clean those where physical contact may cause an issue with the quality and finish. There are other considerations to take into account, such as the type of contamination to be removed, as well as the web’s speed and its width.


In many instances, contact web cleaning remains a prominent option, particularly for label printers and those converting filmic materials. Such systems use adhesive rollers that are in contact with the full width of the web, breaking down the boundary layer and lifting dry and unbonded contamination from the web’s surface. Breaking down the boundary layer is an important part of any web cleaning process. The boundary layer is caused by the ambient air that the web drags along when in motion. It draws contamination to the substrate, trapping it either beneath the layer and directly on the web’s surface, as well as holding it within the boundary layer.


Contaminants are then transferred to a second roller with high adhesive mass, which removes debris from the first roller and prevents recontamination. As contamination builds up on the adhesive roll, it should be checked and changed. This is an essential step to ensure the quality and performance of a contact web cleaning system is maintained.


The benefits of elastomer-based systems include comfortably operating at speeds well in excess of 200 metres per minute and picking up extremely small particles. They also provide a visible and effective cleaning process.


All of the above underscores the importance of adhesive rolls used in such systems. Integral to the overall success of contact web cleaning, they are figuratively and literally the glue that holds contact web cleaning together.


Figure 2: Positioned ahead of print units or engines, web cleaning is at the coalface of getting webs of material ready to receive in


Important considerations when specifying such a critical component in the process include the following: the base material, where thickness, consistency and profile are necessary to ensure a constant high wind quality; moisture resistance, to ensure the material remains stable during transit, storage and use; the adhesive, which should be formulated to work effectively with all elastomer-based contact cleaning systems. Practically, perforated and easily removable sheets facilitate efficient and effective change of the adhesive surface to maintain the roller’s performance.


Adhesive rolls that MAPP supplies to the market are designed to help printers and converters overcome these challenges, such as by being compatible with all makes of contact web cleaner, including 70 perforated and removable sheets, having more than 22 metres of adhesive per roll and using an unmatched adhesive coatweight and high adhesive mass to clean webs 2-3x better than competitive products.


Figure 1: Contact and non-contact web cleaning are important tools in the arsenal of any printer look to deliver tip-top quality


Figure 3: In the case of inkjet, dust and debris left on the web can be catastrophic to the overall process


Such characteristics help ensure contact cleaning continues to provide an ideal solution for web-fed systems and the printers relying on them to decorate and convert high-value and saleable labels and packaging.


26


July/August 2024


www.convertermag.com


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