Up to now, the printing of flexible packaging has been limited to the established processes of flexographic and rotogravure. More recently, new possibilities offered by infinitely variable size web offset printing-such as that offered by Muller Martini in its Alprinta V-have become a viable alternative for manufacturers.

Q: When did the company launch the Alprinta?

The Alprinta was introduced at drupa 2004. Since then, more than 35 have been sold worldwide, with more than half flexible packaging capable. The Alprinta has a true commercial ink train with four form rollers and the option of running a segregated ink train (separating the water and ink form rollers). It is also a completely servo-driven press, allowing it the flexibility for custom applications.

Q: Describe the ink zone control feature?

We designed our own individual hardened sliding segments, not perforated blades that are the norm. This allows precise control from one ink zone to the next. We were also able to develop a control system with an open architecture that will allow us to take advantage of the rapidly developing active color control systems that are coming to market. It also uses the latest JDF and CIP technologies to get salable product off the press in the least time possible.

Q: What applications does the Alprinta work best for?

In the packaging markets, wraparound labels of films and papers and shrink sleeves are our strongest applications. Shrink sleeves especially because of their critical controls of web tension and printing length.

Q: What are some of the benefits of using the Alprinta V?

Our goal is that it must be possible to produce flexible packaging in a range of print lengths at a reasonable cost. Web offset machines have been missing this cost-efficient size range. The costs for a size set in the form of conventional printing inserts have amounted rapidly to six-figure euro sums for an 8-color machine and prevented the establishment of more offset printing in the flexible packaging segment. These expensive offset solutions have thus only prevailed where merely a small number of different size dimensions has been required. For example, as early as the 1980s, Tetra Pak started to print certain packaging for liquid foodstuffs using web offset.

However, the high costs associated with a range of sizes are now a thing of the past for web offset printing. With the Muller Martini Alprinta V, the print length is changed as required by replacing the actual size parts: the plate cylinder and the blanket cylinder. This is a quick procedure accomplished without the use of tools.

Infinitely variable size web offset printing now meets the requirements for printing packaging. These include low-cost printing methods, their rapid manufacture, a high level of standardization, avoiding high levels of volatile organic compounds (VOCs) and short machine make-ready times.

In competition with the established processes, web offset has become a useful supplement, particularly for the range of small and medium print runs, where printing plate costs and response times play a key role today. A large number of alternative solutions are opening up for packaging printers, which will permit them to expand their product range. As a result, flexo, gravure, web offset and digital printing will be found increasingly under one roof and will complement each other.  

Muller Martini