Packaging continues to be a growth market, and within the packaging sector, flexible packaging is arguably the fastest growing segment. According to a Smithers Pira report (Future of Global Flexible Packaging to 2020), the global market for flexible packaging is projected to grow 18% by 2020.
This growth brings with it new challenges for flexographic printers. Chief among these is the increased diversity of printed packs – trends of smaller lot sizes, a wider variety of products and packaging formats, and a growing desire to regionalize packs as well as vary them seasonally and in support of specific events.
This article was written by Dr Dieter Niederstadt
According to the Smithers Pira report, flexible packaging is the most economical method for packaging, preserving and distributing food and other consumables. Flexible packaging also carries a lower supply chain cost than glass and metal and can deliver more shelf appeal and product protection. This means while flexible packaging is on the rise, glass and metal packaging are on the decline in many regions. The lighter weights of flexible packaging reduce material and shipping costs.
They also increase consumer convenience, since pouches can be easily stored, and provide consumers with the ability to get food on the go, instantly and at any time. Consumer product companies (CPCs) want consumers to be able to prepare a microwavable meal from a pouch as quickly and conveniently as they can eat a breakfast bar. The diversity of packaged food products using flexible packaging solutions is endless.
Traditionally, flexible packaging using flexographic printing technologies has been manufactured in lot sizes averaging about 15,000 metres (49,212 ft). In most plants, job changeover times can be an hour and a half or longer, depending upon the type of equipment, number of colours that must be changed, press modules required, etc.
Clearly, as lot sizes decrease, the economics of conventional flexographic printing are challenged. It is for this reason that there has been increased interest in digital printing solutions for label and flexible packaging production.
Technologies are now market available that will allow flexographic printing to strengthen its competitiveness, particularly for short run small-lot jobs, to ensure that flexography remains the printing process of choice for CPCs well into the future.
Fixed colour palette printing expands market potential
Printing with a fixed set of inks is also gaining popularity among both offset and flexographic printers. This approach typically uses CMYK, or CMYK + Orange, Green and Violet or Blue. The latter, often referred to as Extended Colour Gamut (ECG) printing, can completely eliminate the use of spot colours and delivers better quality than CMYK alone. ECG printing can also match a wider array of spot colours than CMYK alone. Some experts estimate that ECG can match as much as 90% or more of the 1,726 named Pantone spot colours.
In addition to eliminating the need to use multiple spot colours, fixed colour palette printing also reduces press make-ready and change-over times. In fact, in many cases, there is no need for wash-ups between jobs since there is a fixed set of inks being used – just a simple change of plates and run-up to colour. This significantly improves throughput and brings down the cross-over point between flexo and digital. For label UV flexo, the cross-over point can be as low as a 400 metre (1,312 ft) job length.
Using the fixed colour palette printing process, flexographic and offset printers are also able to significantly reduce ink inventories and waste. In addition, it makes it easier to include jobs from multiple clients in the same run, also known as combo printing, co-printing or ganging. All of this saves significant time and cost and better enables the faster time to market demanded by CPCs.
While certain colours will still require a spot colour ink, the number of those inks required is vastly reduced. And, as pointed out above, the press is never down for wash-up and make ready between jobs!
If your company is digitally printing, you are likely to be already running a fixed set of inks on those presses, so why not try it in flexo as well? After all, you – or your repro house – already understand how to make multi-colour separations! For print jobs that are designed using spot colour, it is necessary to reformulate the spot colour into a fixed ink set, creating that colour with a process build rather than using a single ink.
The skills of a repro house can come in handy here. The repro house must be able to build the formulation with confidence and partner with your team to enable efficient delivery. The press must also be profiled, and that profile must then be validated. The press must be checked for performance, fingerprinted and then tested for repeatability.
There is no point in starting a print run, and then having the colours drift over time or across jobs. It is critical to develop a process that delivers consistency on a long-term basis when printing flexible packaging with a fixed set of inks.
Although digital printing is still a niche technology in flexible packaging, there are some lessons flexo can learn that will help keep flexography viable. These include the production flexibility gained by using a fixed set of inks – a standard process in digital printing.
Choosing the right plates for fixed colour palette printing
Achieving brand spot colours with ink layers, or process colour printing, as opposed to using a spot colour ink, requires perfect plate registration to be able to match the predicted spot colour target as accurately as possible the first time around.
One approach is to use a photopolymer or rubber engraved sleeve. The registration capability of today’s flexo sleeve technologies is best in class. That makes it a good fit for fixed colour palette printing. However, there are downsides to this approach as well. First, the worldwide market share for sleeves is estimated at approximately five per cent. With this low demand level, the availability of the materials can be somewhat limited.
The second and most significant disadvantage for fixed colour palette printing using sleeves is the way sleeves are imaged or engraved over their complete printing width, making last-minute job changes impossible. Since sleeve delivery for special sizes can take several weeks, printing with sleeves requires a well-planned supply chain with zero tolerance for changes.
And changes are one thing that are an everyday part of a flexographic printer’s life.