Revved Up to Retrofit

Narrow-web label converters looking to expand into flexible packaging may want to consider press retrofitting as a first step—but there are tradeoffs.

Imagine this: your first car is a '92 Ford Mustang, two-door with an obnoxious red interior. While it met your initial driving needs, you are ready for something better—a little extra power, a CD player, and maybe a sun roof. While right now purchasing a new car would be a real stretch, you know you can get some, but not all, of what you want by upgrading what you have.

Converters running narrow-web presses designed for pressure-sensitive labels are facing a similar situation when looking to drive on the flexible packaging highway. Their standard presses are great for heavier paper stocks, but flexible packaging brings with it the need to run thinner film substrates. While purchasing a new press may be too large and risky of an investment at this point, retrofitting a press is an option to consider.

Press retrofitting, though, must be carefully thought out and approached in terms of the problems that need to be addressed, and in your expectations. Terry Trexler, product manager for Gallus (Philadelphia, Pa.), lists the primary issues that must be tackled as web tension, heat management, static build-up, and ink adhesion. Each of these must be addressed to a degree determined by the individual application.

Addressing retrofit issues

Web tension control is one of the main issues to be tackled when retrofitting, and it needs to be addressed in several areas of the press. Pat Bowdy, engineering manager at Ko-Pack (Williston, Vt.), says the underlying requirement for precise tension control of films is because of the instability they exhibit when tension is applied.

Gary Teeter, retrofit applications engineer at Mark Andy (St. Louis, Mo.), points out the sensitivity of running films on a standard label press. "Infeed pacing is critical to web tension and management of the thinner unsupported substrates," he says. "Standard label systems typically cannot be set low enough, which results in too much web tension."

Teeter also points out the importance of using low inertia idler rolls. These help reduce strain added to the film as it travels through the press.

Another important area for tension control, according to Teeter, is to have a separate drive on the plate rolls versus the impression rolls. This prevents web tension changes when making a register change at any station.

Once tension issues are adequately addressed, web drying and heat management come to the forefront and depend on the types of inks used—UV or water-based, says Chris Faust, director of business development at Aquaflex (St. Bruno, Quebec). "A UV press will need some form of chill drum or heat management system, as the films will distort under the UV lamps without it. Water-based inks don't always need chill drums as the air flow and dwell time under this air flow are more important than the temperature of the air itself."

The sensitivity of films to higher temperatures can many times dictate the reduction of temperature in the drying process. Teeter explains that when heat is reduced on water-based ink applications, higher air flows will be needed to achieve complete drying. When this happens, "the support of the web during the time it is in the dryer tunnel is necessary to prevent deflection," he says.

Static is another issue that becomes more prominent when running film substrates. "Films, especially unsupported, can generate a lot of electrical charge, which affects print quality and ink adhesion," says Teeter. "… Static builds up as the web touches the rolls throughout the press and must be removed as often as possible."

A further consideration for improved ink adhesion is the addition of corona treatment on the press. Corona treaters provide the necessary surface preparation to allow the inks to adhere to the non-porous film surfaces.

Matching expectations

Once these problem areas have been dealt with, converters need to understand the reality of what they should expect. Teeter comments that there is always a level of risk associated with any modified equipment. For the retrofits discussed in this article, these risks will negatively impact speed, waste, makereadies, and print quality versus what can be achieved from a press designed specifically for film substrates.

According to Teeter, waste levels could be two to three times higher, due primarily to difficulty registering stations without effecting other stations. In addition to overall speeds being lower, speed changes must also be avoided when operating the press. "Speed changes simply add to the difficulty in maintaining even tension for all substrates," says Teeter.

There will also be limitations on the materials that can be run on a retrofitted press says Denny McGee, manager of national accounts for Mark Andy. "Retrofitting a paper press to a film press may allow for heavier gauge film material to be converted, thus giving the pressure-sensitive label converter the opportunity to test the market for film sales," he states. However, it would be difficult to effectively process thinner gauge films on a retrofitted press.

Teeter sums it up: "As many converters know, retrofits are a viable and widely acceptable option when all risks are assessed and objectives are clear."

So, why retrofit?

As McGee points out, retrofitting a press can allow a converter to test the film market. He says that film materials used in these markets include roll fed type labels, including some shrink sleeve labels, along with some cut-and-stack film materials in single mono-web and laminated film-to-film applications.

Teeter observes that the most obvious benefit of a retrofit is the initial cost of investment in order to "experiment" with the film market. "Retrofits have traditionally been a cost-effective way to expand business plans and develop new business," he says.

Additionally, Faust says that besides simply testing the waters, retrofitting can be a good option for a converter looking to run an occasional film application.

Though at this point, there are a limited number of narrow-web label converters retrofitting, many are interested in the possibility. While the numbers are low, McGee says that he does see converters making the investment in high-capacity drying systems, along with automatic register systems being updated or added to allow for film converting.

Once a narrow-web converter gets a foot in the door of film printing, further investment would be required. "If they get involved [long term] in the film market, a new press with the proper configuration would be needed to effectively compete," says Faust.

Though retrofitting can meet the needs for your first ventures on the roads of film printing, once you decide to go for a long road trip, investing in a new press is most likely the proper step. However, whether retrofitting or taking the plunge with a new press, the first step should begin with an open-minded discussion with press suppliers. They can provide an honest assessment of what will be needed, and what can be accomplished, so you can decide which path is right for you.

By: Joy English