very short adapter carrying the melt from the 80 mm, 30:1 air-cooled Contracool(r) extruder to the die. This enables the die to sit alongside the extruder rather than directly in front of the extruder. According to Glenn, the air-cooled extruder offers an interesting and economical side benefit: When the outside weather becomes warmer, the air carrying heat away from the Contracool's barrel can be vented out of the building. When the outside weather turns cold, that same warm air is used to heat the factory. Material feeding is by gravimetric technology to assure high precision and constant monitoring of blending and feeding, according to Glenn. The in-line cylindrical filter screen is built into the section of the conduit emerging from the extruder. Access to the screen pack at the 90-deg bend makes cleaning much more efficient, says Glenn, adding that this feature saves time in screen changes, although he notes that the melt quality from the grooved feed extruder is such that changes are needed less frequently than with other older lines. "Typically, one change after six weeks of running is all that has been needed, which really helps us maximize our uptime."

"Swing Line" Means Flexibility
The new Battenfeld Gloucester blown film system is a "swing line," meaning it will process both low- and high-density materials. Apollo's business has been mostly in low and linear low-density polyethylene products. However, the company has worked with HDPE and expects to be producing more products in both standard and high molecular weight HDPE in the near future. Glenn explains that some of the "swing" features of this line include the die, the internal bubble cooling (IBC) control, and the grooved feed extruder, which

can process even HMWHDPE at high throughput rates. The IBC reduces set-up timeto a quarter of what it had been, he notes, and its uniform cooling of the bubble increases output as much as 35%. The Digisonic(tm) layflat control (from Battenfeld Gloucester)on this line uses patented noncontact sensors to precisely monitor bubble diameter. On this line, there are two sets of sensors: one set for LD and medium-weight HD materials, and another set for HMWHD. Glenn says layflat width and bubble dimensions remain virtually the same throughout entire runs with no intervention.

Low Profile Die Saves Time
The die is a 12-in. model of Gloucester's taper lock alignment and pin insert technology. The Optiflow's design allows easy die gap changes, an essential asset in a swing line, Glenn reports. He explains that, because the total height of the die is less than 40 in., the increased centerline distance from the die to the nip increases cooling and throughput rates. The shorter design also significantly reduces polymer residence times. This improves film quality by minimizing or eliminating the material degradation generally associated with longer residence times. Glenn is most impressed by how the Optiflow's height saves time. Platforms or steps around the die are not needed. The operator can see the frostline simply by walking over and looking in. The film is easily grabbed to begin the string-up process, using a fraction of the time it takes with a conventional die. That translates to significant time savings on startups and restarts after changes. "Overall," says Glenn, "it's a die made for easy use, and it's obvious our operators like working with it much more than older designs."     Continue   or    Home