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New Bag Printing System Eliminates Product Rejections

April 1, 2014
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In 1937, in Winston-Salem, NC, Krispy Kreme introduced its now famous doughnuts made from a secret yeast-raised recipe created by a New Orleans French chef. Popularity of the Original Glazed doughnut spread rapidly, and by 1973, Krispy Kreme was a southeastern U.S. chain of 60 shops. It expanded internationally starting in 2001 and by 2012 celebrated its 500th shop opening outside the U.S. Now in 22 international markets, Krispy Kreme doughnuts are enjoyed worldwide.

Coding and Marking Bags Presents Multiple Challenges
Krispy Kreme’s U.S. plant in Winston-Salem packages doughnut mix in 50-lb valve-type multi-wall Kraft bags measuring 19 7/8 x 22 1/8 in. They fill 7000-8000 bags per day, and were printing the ingredient statements on the filled bags using a nine-head HP inline ink jet system. The batch identification, date, and barcode were printed on the side of the bag with a large character inline ink jet printer. Since this plant supplies 12 overseas locations, it must also print ingredient statements in multiple languages. Graphics such as the kosher symbol and Krispy Kreme logo are sometimes added.
    Ingredient statements must be accurate and readable. Achieving consistent print on the irregular surface of a filled bag with online ink jet is difficult at best. For Krispy Kreme, getting perfect alignment of nine print heads to produce complete ingredient statements and product information was troublesome and unreliable.
    Also complicating results, the software was not well suited for printing in a variety of languages, including non-Latin script and characters, such as Arabic and Korea. The result was time consuming set-ups, poor print quality, and rejected shipments at overseas locations.

Contact and Control Provides Print Resolution
With these ongoing problems, ads from Iconotech promoting its printing systems for replacing labels and/or pre-printed bags alerted Krispy Kreme to the existence of a completely different approach. Iconotech’s printing technology is a direct contact, plateless printing process that uses black and white line art to create print layouts in software supplied with each printer.
    The key to the process is the print stencil, a disposable, low-cost print medium composed of a Mylar film mounted onto a nonwoven fiber backing. The film provides a large 11 x 32 in. print field for placing text, graphics, and barcodes anywhere in the layout. Print layouts are output from the software to a thermal imager which burns through the Mylar film exposing the fiber backing through which ink can pass onto the face sheet of the bag or box. This provides high-resolution print for barcodes, any type and size text, and graphics.  
    The process is simple and changeovers are fast and easy. Print stencils are generated for each print run, take one minute to produce, and yield up to 5000 prints.
    Iconotech’s line-up of printers all share the same basic print module. End-users choose the type of feeding option suitable for their product (gusset bag, valve bag, die cut, rsc case) and throughput requirements. Hand feed, shuttle feed, strip feed, vacuum feed, and nearly continuous automatic vacuum feeders are all available. The overall design from layout to print stencil to feeder allows product to be printed in the flat prior to filling, thus assuring the highest quality print possible on the irregular surface inherent to multi-wall Kraft bags.

Upstream Automation Meets Throughput Demand  
Opting to make the change to Iconotech one step at a time, Krispy Kreme chose to start with a hand fed printer, the Optimizer HF. The advantage of this system is that it allows both upstream and downstream automation to be added as throughput demands increase.
    A short five months later, Krispy Kreme wanted to upgrade to automatic feeding to handle its increasing volume. Adding the new KR-U feeding system proved to be the right decision. The feeding system combines a staging conveyor, vacuum feeder, and transfer belts sufficiently powerful enough to handle valve and gusset type multi-wall Kraft bags, die cuts, and rsc cases. This equipment was designed for easy integration with the Optimizer HF printer that Krispy Kreme was already using, allowing Krispy Kreme to become the first installation for Iconotech’s Optimizer KR-U.
    The KR-U provides a nearly continuous in-feed process to the printer from a single side-entry point. A single operator can place 10-in. tall stacks of about 60 valve bags on the 10-ft staging conveyor. Media is then indexed over to the loading lift table. The lift table rises to the pick-off position where the vacuum feeder picks off bags one at a time from the top and moves each to the transfer table for delivery to the printer bed. Feed dogs inside the printer bed drive the bag through the nip point where it is contacted between the print cylinder and impression roller creating print up to 50 pieces per minute. The printer accepts bags from 12 x 18 to 36 x 36 in. long.
    When empty, it drops down to receive the next stack. Total reload cycle is 5 seconds. The 10-ft conveyor holds three stacks of bags, one in the lift table and two waiting.  
    As Krispy Kreme expects its production to increase and looks to attain maximum throughput, the addition of a restacker and return conveyor would complete the system. This would allow for printed bags to be recaptured in a restacker in bundles of 25 bags after exiting the printer. They would be brought back around to the operator on a return conveyor for additional printing on the other side of the bag or re-palletizing.
    With the implementation of the Optimizer KR-U, Krispy Kreme has met customer expectations on print quality, eliminated the product rejections suffered by the international sales department, and met increased production with plenty of capacity still available.
           For more information on Iconotech (Clinton, CT), visit www.iconotech.com

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