An innovative system of tangential cutting allows for lowers maintenance time, reduces costs and increases both cut stability and constancy.
by Vittorio Pesce
Expando is an innovative cutting system produced by Mario Cotta, the internal division of the Italian Zincometal company, which provides significant advantages and benefits to customers operating in the field of cutting paper, tissue and converting of flexible materials. Simone Jaselli, director of the division, explains the main technical content: «Expando is a tangential cut system which is particularly suitable in all applications with a high number of cuts and frequent format changes».
A new concept
The Expando system consists of two units: a knife holder and a counter-knife mutually connectable by means of a pneumatic piston coupling. The cutter holder is mounted on a bracket with ball recirculation trolleys, which slides on a specific linear guide with expanders tires for locking and is also equipped with mechanical parking brake. The counter-knife, instead, is mounted on an expandable chrome shaft. Once the expanders are activated, the counter-knives are locked in a precise and stable position. Compared to traditional cutting, the main new feature of the counter-knife is the easy replacement of the cut ring, which is called “Expandette”. Jaselli details: «Expandette consists of an HSS steel ring of long duration with two cutting edges, with a thickness between 1 and 1.2 mm. Thanks to its “omega” profile, i.e. interlocking, can be coupled to the support in a non-final manner, and therefore can be dropped and replaced without disassembling the expanding shaft: this represents, without a doubt, a huge advantage».
For what reason? «In traditional systems, when the cutting edges are worn and need to be sharpened, it is necessary to remove the shaft, all counter-knives, resharpen the blades, reassemble everything and run the machine settings. In Expando system, instead, the cutting ring Expandette is not coupled in a definitive manner to the support, but can be released directly from the shaft. Thus, it can be remounted in the machine and restored with a decrease in the total time of the maintenance operations, without changing setting».
The reduction in maintenance time is a very important benefit, because it is in really relevant percentages: «It is of course possible – says Jaselli – to define unambiguously the time saved, because the data may vary depending on the application. However, we can say that in traditional systems the task of dismantling the shaft, the counter-knife and ecc., may last three to four hours, while the replacement of the Expandette ring by Expando system can be done in just 30 minutes on average».
A longer life
There are far more benefits. The cutting edges of the Expandette ring have duration which is considerably higher compared to the traditional ones, thanks to the possibility of maintaining constant cutting parameters (angle, penetration and lateral pressure), since they are made in HSS: this allows to reduce the frequency of regrinds and substitutions, and therefore decrease the amount of spare parts.
Expandette is also equipped with two cutting edges: once the former is consumed, it is sufficient to rotate 180 degrees the ring with a simple maneuver. This way it is possible to halved inventory and reduce regrinding operations. When both blades will no longer be re-sharpened, simply replace only the cutting ring, which has a negligible cost with respect to the entire counter-knife.
And again: the speed of the «format change» is very high, since the counter is connected by the piston, and then follows the knife-holder in positioning; moreover, the cutting quality is constant on all the strips by virtue of the perfect positioning of the knife on the counter-knife, a prerogative of the hooked shift.
«Another important feature – adds Jaselli – is that the counter-support and have three staggered wings which penetrate inside the slots, practically doubling the contact and interlocking surface. This greatly increases the stability of tightening at the same space, and significantly improves the quality of the translation, while decisively reducing the risk of jamming».
Adding up all the benefits, the result is a very high quality cut and a huge overall savings in terms of time, cost management, spare parts, ecc., the initial price, slightly higher than that of conventional systems, it can be amortized over within just two – six months.
Jaselli states: «The Expando system ensures cutting strips up to 50 mm or 25.5 mm in special version, mounts linear sliding guides with recirculating ball type «GL», can be installed on any machine and comes in three versions: with manual positioning; manual «viewed» positioning, i.e. with a mechanical system to represent the absolute and relative shares of each cutting unit, with automatic PC controlled positioning. It should be added that cutting lights as well as shaft length can be customized depending on the application, while the diameters of the shaft and the Expandette ring are provided in about ten sizes ranging from 105 and 360 mm».
The market responds
The Expando system is a product Mario Cotta launched a few years ago, but on which the Inveruno-based brand has decided to step up its marketing efforts only recently. Engineer Simone Jaselli confirms: «Mario Cotta company has always been really very focused on productive and technological aspects, and we have decided to step up its marketing efforts to spread even more widely our products and introduce them in new application areas. And the results are proving us right: as a matter of fact, many companies, including major paper mills, have started using the Expando system, and their satisfaction is our main award».
Guarded and strengthened know-how
Set up in 1925, Mario Cotta company is active in the production of industrial knives and blades and cutting systems are extremely reliable and of high quality. Since 1994, it belongs to group Zincometal S.p.A., and has since then grown to become a leading provider of manufacturers and users in the paper industry and in those of «converting», «tissue», plastic film and textiles from all over the world. By choice, the Mario Cotta performs designing, engineering, heat treatment and assembly of its products directly within the factory in Inveruno: in this way it «guards» and reinforces its know-how, and this is the main strength of the company.
Mario Cotta also has representatives and distributors throughout the world, which allows it to offer to all its customers a fast, reliable and high quality service.
Focus on non-European markets
The visit to the factory in Inveruno is also an opportunity to have mr. Jaselli’s statement on the current general economic. «In Europe the moment is hard for all companies, and it is no coincidence that 70% of our production is exported beyond the continent. In Italy, the situation is even more serious, especially because the situation of the paper is compromised for some years now. We, with foresight, have decided to not only expand the application fields, designing systems for cutting new materials, such as aluminum, plastic, ecc., but also focus a lot on foreign markets».
What are, from this point of view, the most interesting countries? «In China we have been present for more than ten years and it is a market we intend to focus on. The same goes for Brazil, while the situation in the USA is more complex. Other countries are potentially attractive as Turkey and Russia, but it is clear that investments should be planned in good time».