07.07.2011

How far gravure has moved on as a printing technique for packaging

There are three major drivers in today’s market for printed packaging, and at first sight they appear to be contradictory. How can the demand for highest quality print be matched with that for ever declining run lengths, when keen pricing is taken for granted? It’s the puzzle that printers continue to battle with, as brand owners drive harder bargains. In the end, only the manufacturers can solve the problem with advances in technology that bring gravure into line with market demands.

A brief overview of the market shows a marked contrast between the USA and Asia in terms of gravure usage. In the former, where flexo is a well accepted process, and in general, quality demands have not been so high, gravure has a lowly market share – probably only one fifth that of flexo. In Asia, where quality demands are more exacting, particularly in terms of special substrates and decorated finishes, gravure has the majority share. The situation in Europe is less clearly defined.

Much of this boils down to cost and simplicity of process. The law of supply and demand, as well as narrower web widths, mean that cylinder engraving costs, always cited as the drawback of gravure, are lower in Asia. There, supply is plentiful and cheap because of lower labour costs, and demand is high because there is not the pressure on ‘green’ technology that exists in the western markets. Gravure presses are essentially simple, and well suited to the high volumes required by the tobacco and pharma markets in Asia. Typically, engraving a new cylinder in Asia will cost around 25% of what it would cost in the USA, with Europe halfway in between.

These are significant market forces, and would appear in the light of the trend towards shorter run lengths to mitigate against gravure. But interestingly, a survey carried out in 2009 showed that in the previous three years, average run lengths on gravure presses had actually risen! While gravure has always been perceived as a high quality print process, with superior ink coverage, brilliance and vignettes, it is now more closely challenged by UV-flexo in these areas, so there has to be a quantitative as well as a qualitative reason behind this. The answer lies in the pre-press costs. While gravure has its problems: cylinder manufacturing and storage; make ready times and the knock-on effect of delivery times in today’s JIT market; waste; cleaning; and solvent issues, flexo, for all its advances in quality has seen costs rise too, and as a more complex process, it is more expensive as an overall investment package if the whole production sequence is considered.

The cylinder problem revolves less around engraving costs than the logistical problem of handling and storing, as well as the proportion of unused investment capital tied up at any one time. Various manufacturers have experimented with materials to replace steel. These include a hollow nickel/copper hybrid that requires an air mandrel, and a steel/PU foam sandwich construction that needs an expanding shaft. Both styles have been developed with a number of the leading gravure press manufacturers, and unlike traditional cylinders, offer a far higher adaptation quotient to different makes of press. Both are lighter to handle and store, and quicker to change over. Saueressig and Janoschka are two companies that have been successful in this field.

Part of the improved set-up times and lower makeready costs relate to the improvements made in colour control and press set-up automation. By bringing gravure into line with register technology long established in offset printing, and more recently UV-flexo, customers whose work is printed gravure can now enjoy a much faster approval process and shortening of delivery times. Ink management technology that brings commercial product in line more quickly with the authorised colour proof, means gravure is relevant to shorter runs too. And the knock-on effect of this is reduced substrate wastage.

One of the technical developments to have made a difference is the new type of doctor blade. Designed initially to cope with the abrasive nature of certain inks, which led to inconsistent tonal values, the new blade was designed to present a more consistent profile throughout the print run. Initially chemically etched, the blades are now produced using automated grinding machines, but the secret is the coating that is applied, which significantly increases the service life and improves ink coverage for high definition. The Swiss company Daetwyler has been successful in pioneering this technology.


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