Gravure cylinders offer clear cost advantages at Zwart, writes Ed Boogaard
“This is a revolution in gravure,” says Harry Sieljes, director of packaging gravure specialist Zwart, in Amersfoort, The Netherlands. He is convinced of the quality and the advantages of the new gravure cylinders from Twentse Graveerindustrie (TGI). The secret is in the cylinder core. It is no longer made of steel, but of a lightweight synthetic material (see illustration).
TGI, began development of the synthetic core about three years ago and Zwart was happy to act as a test site. Director at TGI Peter Weber and André Steghuis (director at TGI Gravure Techniques) explained the development during an open house organized by Zwart in November to introduce the new technology. “During the last 25 years various manufacturers have made attempts to develop synthetic cores for gravure cylinders, but they have always become stranded because of the high costs involved. Technically it has actually been possible since the early nineties, but from the beginning of our investigations we have concentrated on looking at the possibilities of cheaper production processes.
“Lightweight cylinders have many advantages, but in the last few years particularly the cost aspect has become very important. They provide cost advantages both in production and for the user. This is because of the material used and also, for example, due to the shorter delivery time of the cylinders.”
Ten per cent less
André Steghuis estimated that cylinders with synthetic cores are approximately five to 10 per cent cheaper than cylinders with steel cores. Harry Sieljes also saw other advantages. “Thanks to the lightweight cylinders, the working conditions have improved, the set-up times are shorter and we have less chance of damage,” he enthused. With a stock of approximately 4,000 gravure cylinders and an average service life, Zwart expects to have completely transferred to lightweight cylinders in five years, he forecast. Until that time ‘synthetic’ and ‘steel’ will be used together.
Not much difference can be seen from the outside of the cylinders. The difference, however, can be easily felt: for a 390mm long cylinder – the smallest size used by Zwart. The conventional cylinder weighs 21.7kg whilst the synthetic version is only 6.5kg. TGI brought the weight of the new cylinders down to about 35 per cent of the conventional cylinder by replacing the usual steel core with a specially produced composite of resin and natural fibres.
When developing the lightweight cylinder, which had at least to match the steel cylinder in terms of quality and service life, material had to be cheap and quick and easy to process, but it also had to be hard and strong, flexible for use in different sizes and for different machines. Of course, it also had to be resistant to gravure inks and, as Sieljes stated: “The copper must not detach from the synthetic material.” The layer of copper necessary for applying the etched image to the cylinder is applied to the synthetic core by a plating process. This creates a hollow, lightweight tubular cylinder.
During the presentation Weber dropped hints that there are developments taking place towards the production of a completely synthetic gravure cylinder that will make the plating process redundant. “In actual fact, the synthetic core is an intermediate stage. I think in two years time we will have taken a step forward.”
Zwart, soon to celebrate 75 years in business, operates four gravure presses, varying from 390 to 660 mm wide and up to nine colours at Amersfoort. It has 36 employees.
Concluded Harry Sieljes: “This development is important in the competition with flexo. Gravure printing has stood still for a while and remains affected by the image of 10 years ago that it is generally expensive. And flexo has recently been working on its image. But gravure printing is very suitable, for example, for limited editions and the shorter set-up times now possible will certainly help in this respect.”
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