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In blown film, there is certainly more than one way to skin a cat. But Appleton Performance Packaging (appletonideas.com),
actually skinned a whole bunch of cats at its plant in Milton, Wis., where it boosted film output and quality while also speeding up product changeovers, thanks to recent upgrades of components on its blown film lines.

Milton is home of one of Appleton’s three film plants; the other two are in nearby Rhinelander, Wis., and in Turners Falls, Mass. The Milton and Turners Falls plants were originally part of New England Extrusion, purchased by Appleton a few years ago. The Milton facility houses three single-layer lines and one three-layer coextrusion line that produces primarily specialty lamination films for food packaging and other high-end applications. One line is furnished with a 400-mm die package to produce film in layflat widths from 32 to 60 in.; a second has a 450-mm die for layflats from 40 to 80 in.; the third a 500-mm die for 43- to 87-in. widths.

“Our mission is to have top-of-the-line technology in all of our plants,” remarks Bryon Task, Appleton’s plant manager. “The lines in Milton were state-of-the-art when we bought them, and we fully intend on keeping this equipment state-of-the-art as it gets older.”

In blown film, output and gauge control are king. When supplying film to be laminated, controlling thickness fluctuations is even more critical, as even small swings can foul up the converting process, generate scrap, and create unhappy customers. In the past, processors might compensate for thickness variations by “overengineering” the film so that it meets the customer’s specs but consumes more resin than is really required.

So faced with aging lines and more demanding customers, Appleton weighed its alternatives and decided on retrofitting its current capacity with bubble-cooling components supplied by Addex Inc., Stoughton. Mass. (addexinc.com). Earlier this spring, Appleton completed installation of Addex Internal Gauge Control (IGC) system—IBC pancakes with air-controlling sliding fingers that aim cooling at the melt as it exits the die—teamed with Addex’s Digital Internal Bubble Cooling System (DIBC). The latter is a five-sensor system with a high-speed, servo-controlled, air-regulation valve that performs split-second corrections in bubble size at or below the frost line. On the 400-mm line, the IBC package is actually a five-pancake arrangement in which two of the stacks have the sliding fingers (the others are strictly intended to enhance throughput).

The cost to refurbish all three film lines was significantly less than for one brand-new line, but Task says they are now producing higher quality film at increased throughputs. Running at low blow-up ratios of 1.43 to 1.95:1, Appleton saw an increase in output of 25% on some products. “On all the installations we have seen a definite increase in bubble stability,” notes Task, adding that stability is critical to boost production. Task also reports a 50% improvement in gauge control at 3 sigma.

In Milton, Appleton runs more than 100 different products on its three lines. That places an imperative on quick changeovers. “We have seen a huge reduction in time to get the film to the right layflat width with the digital IBC control system compared with the analog system we had,” remarks Task. On the 400-mm line, moving from 49-in. layflat to a 36-in. layflat took 10 sec instead of 10-20 min for the previous system to make the switch.