Evolution of Slitting-Rewinding in Narrow web label converting-An Indian perspective!

Evolution of Slitting-Rewinding in Narrow web label converting.

                                                                             An Indian perspective!

Slitting, rewinding and more, are pre-printing and post printing processes in the narrow web label printing industry. Prior to printing, larger width labelstock rolls or jumbo rolls as they are referred to, must be slit to the size as per the printing format of the label job in hand.

The operation basically involves unwinding, slitting with circular knives or razor blades and rewinding. Paper stocks are slit with circular knives while filmic substrates are slit with razor blades. Additionally, the equipment would have web aligners and tension controls.

Narrow web label printing in roll form made its entry in India in the early 1970s when very narrow flatbed label presses imported from Japan, started being used to print labels. In the earliest times 4 or 5-inch-wide label presses were in use on which single label across was printed. So, post printing  slitting was not required. These presses would print at 5 to 10 meters per minute.

By the 1990s, rotary narrow web CI label presses like the Mark Andy 830 were launched and started going wider to 7inches and on to 10 inches enabling printing of multiple labels across the web with need to slit them after printing and die cutting. Narrow web slitting and rewinding started being done online with an extra die cutting station and dual rewinders on the presses. These presses would run at anything between 30 to 50 meters per minute. It was an innovation at that time, to do unwinding, printing, die cutting and slitting online in a single pass.

 

Towards the latter half of 1990s, when the modular presses like the Mark Andy 2200 were launched with speeds going up to 100 meters per minute and the demand for self-adhesive labels started to rise, converting companies started feeling the need to increase production. It was felt that online slitting rewinding was slowing down their speed especially when there was need for frequent changeovers that took a lot of time. 

Instead of investing in another label press, it would be better to invest in a slitter rewinder. At this time, an offline narrow web slitting rewinding machine complementing the width of their label presses became a necessity. 

With the start of a new Millenium, FMCG and Pharma companies in particular, started insisting on inspection and defect detection of labels supplied to them. Online inspection would further slowdown the label conversion, so offline slitter rewinders were upgraded to perform unwinding, inspection, slitting and rewinding. These would have web aligners, sensors to inspect labels, tension control, slitting and rewinding. A few years later, with the adoption of UV Flexo, printing speeds went up further to over 200 meters per minute. With the growth of retail consumerism, marketing teams of brand owners demanded embellishments, barcodes, various types of varnishing etc. on labels. Each process slowed down the machine speed when finishing online. In such a situation the simple slitting and rewinding machine became a finishing machine. It now has all that was mentioned before, plus servo drives,  registration control, die-cutting, waste matrix removal, defect inspection, slitting and rewinding.

Label printing technologies continue to diversify into different tangents, what started from just flatbed block printing, transformed to be employing technologies like intermittent letterpress, rotary flexo, screen, gravure and combination of all mentioned here, with a host of embellishments. The decorative processes included hot foiling, cold foiling, varnishing, embossing, debossing and many other such techniques. The diversity has culminated in the growth of digital printing whereby the short runs and personalization has received a shot in the arm. With the futuristic digital label printing and growing need for short runs, offline finishing has become an absolute necessity.

The transformed slitter rewinders in the narrow web label industry to complement digital label printing became further evolved to be finishing equipment with a lot of automation, higher speeds and capabilities to have one or two flexo stations to do hot or cold foiling or multiple types of varnishes, print barcodes with monochrome digital barcode printers, inspection system, intermittent or full rotary die cutting, waste matrix removal, slitting and rewinding finished label rolls. All this is offered with automatic slitting width blade setting systems. As the industry evolves to take in its fold products like in-mold labels, shrink sleeves and pouches, sheeting and conveyers are added with counting and stacking options for increased productivity.

These finishing machines have become customized to the specific needs of discerning converters who attend to a diverse range of product offerings. The modern-day slitter rewinders or finishing machines have become a necessity to embellish, overprint and finish the printed web into different products while the main printing line keeps delivering more printed material with less!

The upgraded slitter rewinder, renamed as finishing machine has now become a necessity for any progressive label converting facility. A friend from leading label company that has multiple units in the Middle East, said to me, “the scenario has evolved such that for every press that we acquire, it has to be complemented with a finishing machine or an evolved slitting rewinding machine.” He further asserted, “this is to achieve more, with less!”

Written by Harveer Sahni, Chairman Weldon Celloplast Limited New Delhi India May 2024

The above article is written for publication in  Magazine published in UK

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