Dieter Niederstadt
The global market of flexible packaging is projected to grow 18 percent through 2020, according to Smithers Pira’s The Future of Global Flexible Packaging to 2020 report. The report also states that flexible packaging is the most economical variety, preserving and distributing food and other consumables.
While glass, metal and paper packaging are on the decline, innovative food pouches are seeing big demand, offering lighter weights to reduce material and shipping costs while increasing consumer convenience. Pouches can be easily stored and they give the consumer the ability to get a meal on the go, instantly and at any time. Consumer product companies (CPCs) have an interest in seeing that consumers can prepare, as examples, their microwavable chicken tikka masala meal from a pouch as quickly and conveniently as they can eat their bio muesli breakfast bar.
The diversity of food products using flexible packaging solutions is endless. This diversity of printed packs, however, is putting a tremendous strain on the packaging supply chain. Whereas the demand for small lots is growing, flexo printing is averaging a run length of around 30,000-ft. and 90 minutes of job changeover time.
With digital knocking on the door, positioning itself to take over these shorter runs, flexo must strengthen its competitiveness, particularly for small lot jobs, to ensure it remains the printing process of choice for CPCs well into the future.
Fixed Ink Set Printing
Printing with a fixed set of inks eliminates the use of spot colors. There are many benefits to this process, but the primary one is the ability to gain efficiencies during press production by reducing makeready and changeover, thereby improving throughput and accelerating time to market as requested by CPCs. It also makes it possible to substantially reduce ink inventories, as well as the time spent in formulating them. In addition, it makes it easier to include jobs from multiple clients in the same run, also known as combo printing or coprinting. These both save significant time and cost.
Fixed ink sets, also referred to as expanded gamut (EG) or fixed color palette printing, are able to achieve a very close match to most spot colors, generally using a set of seven inks: CMYK with orange, green and violet (Image 1 and Image 2), or just CMYK. While certain colors will still require a spot, the number of those inks required is vastly reduced. And the press is never down for washup and makeready between jobs!
Although digital printing is still a niche technology in flexible packaging, there are some lessons flexo can learn that will help keep it viable. These include the production flexibility gained by using a fixed set of inks—a standard process in digital. If your company is already using digital, then you are already printing with a fixed set of inks, so why not try it in flexo as well? After all, you—or your repro house—already understand how to make multicolor separations!
For spot color print jobs, it is necessary to reformulate the spot color into a fixed ink set, creating that color with a process build rather than using a single ink. This can be complicated, and the skills of a repro house can come in handy. 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 printrun and then having the colors drift over time or across jobs. It is critical to develop a process that delivers consistency on a long term basis, when printing with a fixed set of inks.
Choosing Plate Technologies
Achieving brand spot colors with ink layers or process color printing—as opposed to using a spot color ink—requires perfect plate registration to be able to match the predicted spot color target as accurately as possible the first time around.
Theoretically, the solution is a photopolymer or rubber engraved sleeve. The registration capability of today’s flexo sleeve technologies is clearly best in class and therefore the perfect fit for fixed ink set printing. However, there are downsides to this solution as well. First, the worldwide market share for sleeves is estimated at approximately 5 percent to 10 percent; hence, the availability of the materials can be somewhat limited.
The second and most significant disadvantage for fixed ink set printing using sleeves is the way they 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.