New for Blown Film: Water-Cooled Bubble, High-Output Air Ring

Apparently undaunted by a lackluster economy that has slowed capital equipment investment and stymied product development in many areas, Windmoeller & Hoelscher last month strutted out six new technologies for film extrusion.

Apparently undaunted by a lackluster economy that has slowed capital equipment investment and stymied product development in many areas, Windmoeller & Hoelscher last month strutted out six new technologies for film extrusion. W&H demonstrated the new products, among them a new line that uses water to cool blown film, at a November open house at its headquarters in Lengerich, Germany. W&H, whose North American facility is in Lincoln, R.I., also displayed the latest developments in air rings, winders, and machine-direction orientation technology, as well as complete systems for blown and nano-layer cast film.

The three-day event attracted more than 1200 processors from 40 countries, 70 of them from North America. While W&H did not bill the open house as a preview of its K 2010 exhibit, it is likely that at least some of these products will be displayed at the Dusseldorf show next October. 



Perhaps most noteworthy was the Aquarex water-cooled blown film line. This is believed to be the second commercially available system using direct application of water to the bubble for cooling blown film, following the AquaFrost system that was unveiled at the K 2001 show by Brampton Engineering. Brampton has reportedly sold 11 of these systems worldwide in up to 10-layer configurations. Pack-All Manufacturing in Rockland, Ont., has the only North American installation, a nine-layer line. A small number of higher-tech blown-film processors serving the barrier and medical film business have also developed water-cooled systems on their own. A water-quenched system was also marketed briefly in the 1980s.

Key advantages of water cooling are said to include robust outputs, extremely high gloss, high mechanical strength, soft touch, and high clarity. In Lengerich, W&H ran a three-layer, 8-mil, PP-based film at 660 lb/hr. Medical applications such as blood bags—replacing PVC—are one target application. Depending on the structure and thickness, W&H says outputs of 2500 lb/hr are feasible.

In water-quenched blown film, the bubble is blown upside down, meaning the extruders are situated on top of the tower. While W&H did not offer much in the way of design specifics, a key element of the line is the water-calibration unit. “What’s crucial is the way in which the water contacts the film, how we regulate the amount of water that is used, and how the water is suctioned off,” remarks Andrew Wheeler, vice president. “The last thing you want to do is wind up wet film.”

The water calibrator can be adjusted up and down to adjust for frost-line height, Wheeler explains. It has a fixed diameter, allowing for blow-up ratios of 2.5:1.

Water-quenched blown film isn’t entirely new to W&H, as it has furnished upside-down wet haul-offs and winders since its purchase of Reinhold six years ago.



W&H also displayed a more conventional means to cool blown film with the Opticool air ring. At the K 2007 show, W&H ran a three-layer line with a stacked (one atop another) air-ring configuration to boost output. This new dual-lip unit optimizes air-flow volume—said to exceed that of a tornado—to provide output rates exceeding that of the stacked units. At the open house, W&H ran the Opticool on a three-layer line with a 16-in. Maxicone C die at 2200 lb/hr, holding gauge to ±2.5%. The air ring will be available across W&H’s die-size range and can be retrofitted to existing lines.

At the open house, W&H also introduced the Optimex three-layer blown film system. Designed to complement the more technically complex Varex blown film line, Optimex is aimed at the mid-range of the film extrusion market. “What this new offering really does is expose W&H’s state-of-the-art technology to a much broader range of film processors,” Wheeler states.

The line features less in the way of expandability than Varex systems and comes with a simpler bubble-sizing cage, haul-off and surface winder. It is available in limited layflat configurations. Depending on the material being run, outputs from 800 to 1100 lb/hr (of fractional-melt LDPE-based formulations) can be achieved. Target markets include carrier bags, lamination film, and shrink and stretch film.

The company also took the wraps off a new machine-direction film orientation (MDO) device. This is a stand-alone unit not integrated with the blown film line. Film is unwound and oriented off-line at speeds above what would be possible with in-line systems. Meanwhile, W&H also unveiled the new Filmatic N winder for blown film. The unit at the open house had a working width of 103 in. and can operate in center, gap, or surface mode.

Demonstrating a recent emphasis on cast film systems for North America, W&H also displayed the Filmex 17-layer line for stretch film that featured nano-layer technology to improve puncture resistance and ductility.

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