The first things we need to take into account when choosing between different printing options for plastic packaging are the type of material and the heat treatment technique. Polyester does not behave in the same way as polypropylene, for example, and factors such as whether or not we need to heat treat our packaging are key to the decision-making process. In this article, we analyse the differences between digital and offset printing and take a look at everything we need to consider when making our choice.
KEY CONSIDERATIONS FOR SELECTING A PRINTING TECHNIQUE
Once we have chosen our material, the batch size will influence our choice of printing technique because each technique comes with a recommended batch volume that is measured in metres. The batch size is determined by the product or item stock turn.
At SP Group, we work with the four existing printing techniques: rotogravure, flexography, digital printing and offset printing. This article focuses on the last two techniques because they have certain distinguishing features that afford them advantages on top of simply getting your designs printed. These features can help you align packaging manufacture with other marketing strategy decisions.
WHAT IS DIGITAL PRINTING?
Digital printing involves printing directly from a digital file onto a material without the need for printing plates and add-ons. All the information on the computer is sent to a printer that is fitted with heptachromy inks and the design is transferred onto the plastic laminate. In terms of job preparation, it is a very simple technique. Since there are no cylinders or printing plates to account for, it is possible to make design changes and this facilitates customisation with results that are comparable to rotogravure and offset printing.
Unlike other solutions that use dry inks (toner) to print onto the substrate, the SP Group HP Indigo digital printer uses ElectroInk which is applied to the substrate with or without an electrical current.
WHAT MAKES DIGITAL PRINTING WORTHWHILE?
In our opinion, digital printing is the best option for limited batches of between 1,000 m2 and 3,000 m2. In these cases, digital printing is more economically viable than alternative printing options.
WHAT IS OFFSET PRINTING?
Offset printing is most commonly used for printing onto paper to create packaging and other products such as magazines. Developments over the last few years mean that the technique can now be used to print onto plastic materials or substrates and offset printing has positioned itself as one of the most innovative packaging printing options on the market.
Offset printing is based on a system of aluminium plates with polymers that can repel water and set the ink. The design is printed onto plates; one for each colour. Once they have been printed, they are fitted onto cylinders that drive a mechanism which allows the plates to set the ink. The term ‘offset’ refers to the way in which the image is indirectly printed onto the medium.
It is worth noting that this system works with Electrom Beam inks which, in addition to being free from solvents, dry quickly and are very resistant. Another advantage is the low energy consumption, which makes it very environmentally friendly and attractive to companies that are committed to sustainability.
WHY CHOOSE OFFSET PRINTING?
If what we are after is a printing technique that is suitable for small to medium-sized batches of products that frequently change in design, this is the printing system of choice.
CHOOSING BETWEEN DIGITAL AND OFFSET PRINTING
Aside from the technical differences in terms of the actual printing, one of the key stand-out differences between these two printing techniques are the printing plates. As mentioned, on the contrary to offset printing, there are no plates in digital printing because the process goes directly from a file to the printer.
NO PRINTING PLATES IN DIGITAL PRINTING
The fact that there are no printing plates in digital printing means that the batch size can be smaller and this makes it ideal for testing products on the market without generating excess stock. In other words, it saves companies money. This makes small-scale batches that give companies an idea of how well a product will do on the market an option. This is more cost-effective than producing large batches. Once a company has achieved a good outcome, it can transfer the idea over to an alternative printing system, the choice of which will be determined by the batch size.
INCREASED CUSTOMISATION IN DIGITAL PRINTING
Customisation is another of the advantages of digital printing. Customised printing opens the doors to a huge range of opportunities for marketing departments. This could mean creating different designs with a big impact on supermarket shelves or getting consumers involved in the actual design as a means of consolidating the relationship between the brand and consumer.
OFFSET PRINTING AND NEW PROJECTS
Since batches can begin as small as 3,500 m2, offset printing is perfect for new projects with products that have not been tested on the market. In comparison with other techniques, such as flexography and rotogravure, the more batches we manufacture, the more we can offset the cost of creating plates and cylinders, although SP Group does not charge any extra for aluminium plates.
OFFSET PRINTING AND FREQUENT CHANGES IN THE DESIGN
In addition to the above, when we work with products in which we there are frequent changes to the design, offset printing is also our best bet. If we consider everything that creating conventional flexography printing plates or processing rotogravure cylinders entails, any design modifications in offset printing are quick and cost-effective.
OFFSET PRINTING AND MORE THAN ONE PRODUCT REFERENCE IN A SINGLE BATCH
Offset printing also means we can print several different product reference designs in a single batch. The number of different designs that can be printed depends on the size. This is a great advantage for products with a low stock turn that do not reach minimum batch figures. By working on several references in a single batch, the number of square metres increase without having to increase the amount of packaging.
If you would like to find out more about these techniques, or to get an understanding of which is the right one for your product, please do not hesitate to get in touch. We would be delighted to answer all your questions.
