Profit through Innovation - Challenges for inkjet printing in packaging

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Challenges for inkjet printing in packaging

Written by Stefan Slembrouk, 2007

The packaging market holds many potential opportunities for inkjet solutions, but only a very few are offered. What are the reasons for this apparent failure, asks Stefan Slembrouck, and what can the market realistically expect over the next years?

Around 10 years ago expectations were raised that inkjet printing would become a standard in many industrial print markets within a few years. Although it is true that inkjet has been successful in making a significant inroad into markets that were traditionally dominated by screen-printing, it failed to do so in others. Packaging in particular is a huge market with great opportunities for inkjet solutions, but only very few are offered, and merely for sample production.

Why is packaging so attractive for inkjet solutions?

For many years there has been an unbroken trend towards shorter print runs caused by niche marketing and the desire for minimum inventory. Product lifecycles have become much shorter and highly unpredictable due to a hyper-competitive environment. The number of new product launches or relaunches has increased, albeit at a consistently high failure rate of about 90 per cent. In Europe, this has made the average print run in corrugated drop from 9,000 to below 3,000 sheets, and in flexible packaging from 100,000m to less than 25,000m.

But at the same time retail and branding companies have become more aware that consumers take their buying decision in 70 per cent of the cases at the point of purchase, which means that the promotional value of product presentations at the POS is significant. As a conclusion the challenge is enormous: a demand for more colours, sophisticated graphics, extreme responsiveness, short print runs and - low cost! It looks like a tailor-made opportunity for inkjet solutions to jump in and win large market shares. But where are they?

Solution for which application?

From a helicopter perspective, packaging is an industry based on a few raw materials: metal, glass, plastic film and paper, worth in Europe about €100 billion per annum. But the closer we look, the higher the complexity: not only are there numerous combinations of base materials but they are also processed very differently.

Packaging is not only printed and cut but welded and glued, formed, folded and laminated, sometimes before printing and sometimes after. It has to resist rub from forming processes and filling lines, heat and humidity in retorts, it has to be cut and creased and sealed - and it has to comply with a huge number of laws and regulations. Hence, the packaging market does not exist - but there are hundreds of different packaging markets. But yet, packaging is a volume market and any technical solution must be capable to offer high throughput rates.

As a conclusion, there cannot be one inkjet solution for packaging, but only a specific inkjet print solution for a specific packaging application. Hence, for inkjet to conquer the packaging market, dozens of different solutions are needed, providing a balance in print quality, throughput rates, reliability and economics.

Let's have a closer look at each of these criteria in order to better understand the underlying challenges.

Speed and throughput

Whatever application, a technology for printing packaging needs to be fast. Even in short runs, packaging is a volume market and printing must somehow fit the overall production process if it isn't to become a bottleneck. Inkjet solutions that currently provide throughput rates of 50-150sqm per hour are much too slow as a serious alternative to conventional printing technologies.

An alternative would be single pass (or fixed array) systems with a very large number of print heads that offer capabilities per hour from 180sqm (Dotrix) to up to 6,000sqm (FastJet). One of the challenges of single pass systems is to hold the substrate at the required speed in a very accurate position at a tolerance of less than 10 microns, without it being held by plates and drums. If not, drop deviations and colours out of register will result. Therefore the range of substrates needs to be well defined before designing an inkjet press that can print at high speed.

Although it is true that images can be changed within fractions of seconds, substrate changes and cleaning intervals constrain the maximum throughput in practice to 50-70 per cent of the promoted values.

Print quality

Packaging graphics meet two requirements: information and promotion. Information means text and line work, promotion colour and images. Since for legal reasons a lot of information is required, text is often set in very small fonts. Text and barcodes must be readable, therefore lines have to be sharp - a challenge for no-contact inkjet printing.

Psychologically, colour is very important to convey promotional messages. This is great for inkjet printing when it comes to complex photographic images and colour consistency throughout the print job. But it is difficult to print a large area in a single solid colour at high density and overcome issues such as banding and striping. Inkjet heads don't love ink changes, so spot colours are a challenge for inkjet and they are an even bigger challenge for fixed array systems with a high number of print heads.

Does this mean that inkjet printing is just not able to comply with print quality demands from the packaging industry? No, surely not. But it means that there is no simple 1:1 transfer of images that used to be printed conventionally. In order to produce an attractive packaging image with inkjet printing, the image needs to be designed for inkjet printing, or at least it needs to be retouched. And once the RIP is made, the colour remains consistent throughout the entire print job and from run to run.

Reliability

Since inkjet technologies promote themselves as the right solutions for short-run, on-demand printing, it must be expected that they print on press-button. The required reliability must be proven in an industrial environment with dust, temperature changes and humidity - unless a temperature-controlled clean room has been specified.

Inkjet loves printing. Since there is hardly wear and tear in print heads - as long as the inside is kept pristine with a properly filtered and degassed ink - the more often an inkjet printer prints, the better it will perform.

The reliability will be higher the better defined the final application. Not only will the construction design respect particular characteristics of the substrate to print but the entire development and scale up will also be conducted with the target materials and designs. Until a high level of reliability is proven in a standalone solution, it cannot be recommended to develop inkjet printing inline with another operation like laminating or die-cutting or even filling and packing.

Economics

Inkjet printing is economically viable only if the total cost of ownership to the print buyer is compared to the cost of a conventional technology. In packaging, the plate cost is usually invoiced directly to the print buyer (or end user) and does not appear as a production cost. But it is the print origination cost for repro and plate manufacture that drives the cost for short print runs extremely high: for the end user - a cost that does not appear in inkjet printing. And it is the origination cost that is often prohibitive for new product launches and image changes - a concealed market opportunity for inkjet.

An analysis of payback rates for inkjet investments must therefore include a modified business model based on the proactive exploration of new values to end users, away from the reactive pattern of meeting overt demands only.

Inkjet has a great advantage in that only a few cost parameters need control: the depreciation of the equipment, ink consumption and maintenance. The image raster (RIP) will tell how many drops are needed to create an image, and the number of drops can be translated in grams of ink: once the technology is established it provides a very high cost predictability.

Conclusion

Inkjet will establish its position alongside conventional print technologies and it will thrive on the growth of short print run volume. A solution that is targeted at a specific packaging niche will likely be more successful than a generic solution, providing a tailor-made balance in throughput rate, print quality, reliability and economics. Some solutions for flexible packaging, corrugated and labels seem to be around the corner but all of them still need to prove their reliability.

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