Converters and packagers continue to benefit from advances in flexographic printing. Bake-Line Products Des Plaines IL is a good example. The private-label baker has nearly completed a switch from gravure to flexo printing for its paper/film bags of cookies that it produces for supermarket customers across the U.S. Several compelling reasons led Bake-Line to make the switch.
First the cost for developing flexo films and printing plates for new packages is roughly one-third the cost of etching new cylinders for gravure according to Erik White graphics manager at Bake-Line: about $4 versus $12 for an exclusive design he estimates. The photopolymer flexo printing plates can be made in two to three hours via a process that involves exposing the plates to UV light through the film negative. That's according to Bake-Line's flexo printer Fort Dearborn's Flexible Packaging Div. (Elk Grove Village IL) formerly known as Flextech. This division is on the same premises as the prepress house that creates the film Virtualcolor also a division of Fort Dearborn.
Of course White acknowledges that gravure cylinders last longer than flexo plates but he says plate longevity isn't an issue for Bake-Line since copy and artwork are likely to be obsolete before the plate wears out.
Changing package graphics
In fact the flexibility to alter package copy or graphics is an important benefit to the bakery. White cites a recent example of a government-mandated copy change. "For any product containing flour we had to add 'folic acid' to the list of ingredients. In the past I would have had to change a gravure cylinder at a cost of $1 per package. Now I can do the change for the cost of a separation and a plate which is about $400 [per package]."
Because flexo platemaking is less expensive than etching gravure cylinders Bake-Line says its customers now have more freedom to individualize their packages. Previously the bakery offered an economy plan for its private-label customers that included standard four-color process art made with four gravure cylinders that Bake-Line owned. Customers in turn could choose three line colors for a logo and background color. So although the packages were printed in seven colors via gravure under the economy plan customers had to share a similar look with other Bake-Line private-label customers.
Today says White it's a different story. "Once we switched to flexo customers became thrilled that they could have their own exclusive photography design even redesign" he says. "In the private-label field everyone seems to want to redesign their package every three to five years. That was so costly before. But now it's more economical."
Another benefit is shorter lead times. At the time Packaging World was preparing this story Bake-Line had created a new package for its Sun Valley house brand of pecan shortbread cookies. Developing the package from concept through artwork to printed rollstock took only 10 days. "It's amazing" says White. While that's not typical he admits it does indicate how fast a new package can be turned around if need be. "We can have film and plates in a matter of a few hours" says Dan Doherty president of Fort Dearborn's Flexible Packaging Div.
In contrast the typical lead time for gravure was closer to six weeks since the cylinders needed to be sent to an outside vendor for engraving.
Because Fort Dearborn prints the bags on 10-color flexo presses Bake-Line has more line color options for background graphic elements instead of trying to approximate those colors via four-color process. The benefit is more color consistency from bag to bag.
"The problem with [creating spot colors with process printing] is that it varies throughout the run. If your magenta darkens or your cyan lightens it makes your background look different from one package to the next. On a 10-color press I can run a dark blue as a dark blue line color and it's going to stay consistent throughout the run."
Most of the bags for Bake-Line's customers are printed from seven to nine colors plus a clear coating.
Fort Dearborn bought a 10-color press from Comco (Milford OH) a little over a year ago to do this kind of work and it has since bought three more. The presses accommodate web widths to 22". The web width for Bake-Line's bags is 171/4". Press speed for Bake-Line's work averages 300 fpm.
The Comco presses are better at keeping the paper/film structure which has the potential to slip in register since they were specifically designed for printing on films and laminates as opposed to paper-only substrates.
The rollstock that Fort Dearborn prints for Bake-Line is a three-ply structure that consists of an outer layer of 26# clay-coated paper/7# LLDPE (for moisture resistance)/1.25-mil Surlyn® from DuPont that permits heat-sealing through grease and food particles. Bake-Line and Fort Dearborn declined to identify the supplier of the structure.
Automatic register controls on the Comco press also help Fort Dearborn "take the guesswork out of registration especially when you're talking about potentially elastic materials or materials that have some slip properties" says Doherty. Fort Dearborn also uses video web inspection systems to closely monitor registration.
White points out how the ability to hold good register has influenced Bake-Line's package design for the newly developed Sun Valley pecan shortbread cookie bag. He cites how the Sun Valley logo abuts the four-color process image of the cookies and pecans.
"We're not getting any halo there. There's no cyan peeking in no yellow or magenta peeking in. That shows how tight the registration is. It's so good that we didn't even use a holding rule on it" explains White. A holding rule is a border around a spot-printed element that is traditionally used to trap adjacent four-color process-printed colors that might potentially bleed over. The bags are printed with a 133-line screen.
Bake-Line is also happy with Fort Dearborn's ability to match the target color proofs. That's done through careful control of dot gain according to White. "They know exactly what they're going to be getting [when the bags are printed]" says White. "With some printers you can get so much dot gain that it doesn't look like what they're expecting. The cookies can get dirtier a little blue-green. The synergy between Virtualcolor's films and Fort Dearborn's printing gives us packaging that jumps off the shelf."
In the switch from pre-made bags to rollstock efficiencies on the packaging line improved although specific figures weren't available. Previously on the packaging line thermoformed plastic trays of cookies were flow-wrapped in polypropylene film. The film-wrapped packs were then hand-inserted into pre-made gravure-printed paper bags with tin ties and manually sealed.
Now the flexo-printed bags arrive as rollstock (already containing a film barrier layer) that runs on the very same flow wrapper with only slight modifications required for the sealing jaws. No PP film overwrap is needed and the manual tray insertion operation has been eliminated.
Although Bake-Line eliminated the tin-tie reclosure in the switch from pre-made bags to rollstock it wasn't a big concern since the leading national brand that these packages emulate also comes in a heat-sealed bag that lacks a reclosure feature.
Ultimately Bake-Line feels the economies created by flexo printing and the conversion to packaging from rollstock results in attractive packaging better economies and greater flexibility for its customers. And White feels the quality of the flexo printing is so high that consumers can't tell the difference between it and gravure-printed material.