Adviser about Flexible packaging

The printing process is the first step in the production of flexible packaging such as flow packs, stand-up pouches or flat pouches. Printing is always carried out on rolls (roll-to-roll). For most applications, the printing film made of PET, BOPP or MDO-PE is printed on the reverse side – the motif is thus enclosed between two layers of film after the lamination process and is therefore very well protected against abrasion. Flexible packaging is printed using all common printing technologies – digital printing, flexographic printing, offset printing and gravure printing. We present the most common printing processes in this article.

Digital printing

Digital printing is particularly suitable for small to medium print runs and frequent motif changes. No printing plates or cylinders are required, which means that types/motifs can be combined very flexibly. The set-up time is also very short and, where possible, different jobs can be combined. The production time for digitally printed films is usually only a few days.

Currently, two technologies are particularly widespread on the market: liquid toner technology (HP Indigo) and water-based inkjet printing. The maximum processing width is between 760 and 790 mm. Special colours such as Pantone can only be simulated using these technologies (CMYK / Hexachrome). Depending on the printing process, colours and material, the printing speed is between 25 and 80 metres per minute and is usually done in reverse on the back of the printing foil.

Flexographic printing

Flexographic printing is the classic printing process for medium to large print runs. It offers high productivity and extensive options in terms of materials, colour selection and finishing options. In flexographic printing, each colour incurs so-called cliché costs, which can amount to between £100 and £400 per cliché, depending on the size and supplier. Depending on the motif, this can quickly add up to initial costs of £800 to £3,200 (per motif with 8 colours, for example). The setup of a flexographic printing machine is extensive and each printing unit must be set up individually. In addition, the material subsidies for setting up the machine are higher than for comparable digital printing applications. Typical production times range from 10 to 30 working days.

Common processing widths are divided into narrow web (up to approx. 400 mm), mid-web (up to 850 mm) and wide web (up to 1500 mm). Depending on the machine type, number of colours and material, the printing speed is between 300 and 600 metres per minute. Printing is usually done on the reverse side of the material – this way, the printing ink is enclosed and protected between the different plastic layers after lamination. On the outside, partial varnishes with different surfaces can also be applied using flexographic printing – for this purpose, a turning station within the printing machine is often used to turn the material inline.

Gravure printing

Gravure printing is mainly used for very large, recurring print runs. This printing process delivers very high and consistent print quality, even with fine motifs. However, the process is only economical for very large print runs, as there are initial costs for engraving the printing cylinders.
The cost per cylinder ranges from £350 to £2,000 per colour/cylinder. Gravure printing also offers the option of printing special colours such as Pantone. Printing is carried out on both the front and back of the desired film – always depending on the intended use and the planned further processing.