State of the art

With a turnover of approximately € 3850 million per year and a number of employees over the 6200 units, the paper companies of Lucca cover more than half of the entire province industrial turnover, establishing itself as a major player in regional and national export of tissue paper and corrugated cardboard. In particular, the Papermaking District of Lucca, with an approximate tissue production of 1million ton/year, controls about 80% of the national and 17% of the European tissue production.

Along with the metalworking industry, the paper and paper processing industries represent more than 50% of the workforce employed in Lucca province and over 60% of its industrial turnover.

The Lucca companies of the papermaking industry base their success on the quality of their products and the high level of technology. Key factors to compete on the global market, especially in the large scale retail trade, are a continuous innovation and the development of efficient and energy-efficient production processes. The electricity to power the plants, in fact, accounts alone for about 20% of the total production and converting costs for tissue (toilet paper, kitchen rolls, napkins, handkerchiefs, etc.).

The paper sheet production begins with the paper machine, that produces a reel of paper called “parent reel”, of about 2-3 meters in diameter and up to 5.6 meters wide. These parent reels are then processed in the converting line, where reels are printed, cut to the required size and given the pursued characteristics of softness and hand-feeling. The converting line have several distinct operational sections:

  • Unwinders. The paper web is unwinded from the parent reel. More than one unwinder is typically used in cascade, one for each veil layer of the processed paper.
  • Printing units. The printing machine creates the desired graphic patterns and is especially used for high quality paper for domestic use. A four-color high definition flexographic press is commonly used.
  • Embosser. The embosser confers the product a larger volume, a characterizing aspect and a pleasant tactile effect. This is obtained by compressing the paper web between two cylinders, one of which is rubber-coated and the other, in steel, bears a pattern that is transferred through pressure onto the web.
  • RewinderThis is the true heart of the tissue converting line, where the veil exiting the previous stage is rewound to form the so-called "logs", smaller rolls with the same width as the parent reel but the diameter of the finished product. The rewinder also perforates the tissue web at pre-determined intervals (producing whatever sheet size is desired), controls the number of sheets in each log, and produces the pre-determined log diameter. These operations are carried out at constant production speeds up to 700 meters per minute and cycle rates of up to 50 logs per minute. 
  • Log sawTraditionally equipped with disc blades, this machine cuts logs to the desired width. The log saw cuts up to 4 logs per cycle and, in order to keep pace with the production rate, two log saws are often used in parallel on the converting line.

Additional components of the converting line are the corewinder, that produces the cardboard tube (core) on which the tissue web is wound, and the accumulator, that collects logs coming from the tail sealer and assures processing continuity in case upstream or downstream machinery stops temporarily.

A tissue converting line, such as the one described above, can be up to 50 meters in length and made of thousands of mechanical, pneumatic, electrical and electronic components, such as AC engines, servo-motors, axes controllers, PLC, operator interface panels, field networks and I/O signals. The very high system complexity and the difficulties of implementing standardised strategies, make it difficult to ensure high tolerance to malfunctioning. 

The reliability of the converting lines is a key factor for manufacturers, as their machines are inserted in high efficiency production chains. For such a line, each hour of downtime has an estimated cost for the customer of € 2500. It is therefore essential to reduce the downtime by both having a low frequency of failures and, when they occur, a prompt response to quickly restore the system to working conditions. Of particular importance is then to reduce the time to identify and repair the malfunctions. The converting lines manufacturers generally provide training courses and self-diagnostic tools to their customers, to enable them to fix autonomously the problems. Because of the limitations of such instruments, however, in many cases a direct intervention of manufacturer's specialized technicians is required. This entails considerable disadvantages for the customer: firstly, the costs of the intervention are generally high because of the travel expenses of the service personnel; in addition, depending on the distance between the plant and the service centre, several days may pass from the fault reporting to the actual intervention of the technicians at the customer's location.