Extrusion.

NPE was "Tool Time" in many of the extrusion exhibits. Suppliers of dies for blown film, fiat sheet, and pipe brought out innovative designs (a number of which were reported in our May, June, and July issues). In addition, the show hosted introductions of extruders, controls and gauging systems - including one system designed for internet communications.

'UNIVERSAL' FILM DIE

A new pancake die for coex blown film is said to be "impervious to rheology," meaning that it is suited to virtually all resins regardless of their flow characteristics. In addition, the Regular Division (Redi) die from Addex Inc., Boston, uses a new flow-channel design to promote high flow while reducing internal pressure. As a result, the patent-pending die can be built to diameters larger than 15 in., Addex says.

This side-fed die splits the flow of each polymer three times, resulting in eight flows that are later recombined before the material exits the die. What's unique is that the divided flows for each resin are stacked vertically rather than laid out on a horizontal plane. This new arrangement reportedly helps minimize separating forces between the die plates.

The pancake consists of a distribution ring within a feed ring, rather than having each distribution ring stacked on top of the feed ring. All told, the polymer travels through fewer channels than in a conventional pancake die, so there is less chance for polymer degradation, says Addex president Rick von Kraus.

Addex says it avoids the need to optimize flow channels for a particular material by means of a unique diverter plate that splits each polymer flow into an upper and lower half. The flows in each half encounter an intermediary restriction that divides the flow into areas of high and low flow. The differing flows from the top and bottom halves are then combined so that the high flow from the top meets the low flow from the bottom, and vice versa. The result is said to be uniform film gauge regardless of material.

Addex has tested the die with LLDPE and LDPE and is starting work with metallocene resins. It expects to have a Redi unit commercially available next year.

GET BETTER BUBBLE COOLING

For additional cooling above the frost line, a new stacked air ring called the Robert's Stack is offered as an alternative to internal bubble cooling. It comes from Future Design Inc., Brampton, Ont. Each air ring has an adjustable gap and its own blower.

Future Design also introduced a bubble enclosure made of clear polycarbonate sheet that protects the bubble from ambient air temperatures or "shadow heat."

The new HLDK 2/300 dual-lip air ring from Kiefel Inc., Wrentham, Mass., increases the volume of air on the bubble, helping to stabilize it for improved throughput rates and reduced gauge variation.

NEW FLAT DIES ADJUST BETTER

The Epoch R-Series die, the first sheet die from Cloeren Co., Orange, Texas, has new restrictor-bar adjustment technology that reportedly eliminates leakage. Cloeren says there is typically a notch in the die body for the restrictor-bar adjustment device, which can weaken the integrity of the die. Cloeren eliminates the need for a notch with a unique two-component restrictor-bar system in which a piece of the bar enters the die at a 45 [degrees] angle and pushes against a fixed restrictor bar inside the die in order to articulate the preland.

Cloeren also updated its Autogauge die-lip adjustment technology with a version 5.1 that shortens the diebolt adjustment time from typically around 7 min to less than 2 min with the new system. Cloeren achieves better thermal isolation of the adjustment mechanism by means of a two-rod system, whereby the heated rod pushes a second rod to adjust the die lip. Also, the translator and heater rods are now mounted further away from the lips.

EXTRUDERS ON THE INTERNET

An enhanced gauging system for fiat webs offers novel internet communication capability. The Pro. Net system from NDC Systems, Irwindale, Calif., can control up to six scanning frames (versus four in previous systems) and 18 sensors per extrusion line. The 21-in. touchscreen has a new zoom feature that allows you to observe more detail on a section of the roll profile. Also new is a 3D defect map of a roll to aid in slitting. You can rotate the view and set the slice points with your finger.

Most unusual is the system's internet compatibility. Pro. Net is an "open" system based on Windows NT, TCP/IP networking, and the Java programming language. The internet can be used to set up and troubleshoot remotely, view multiple process lines from a single location, send and receive e-mail to and from the process line, and access on-line video help. With the aid of a miniature video camera, line operators can hold a video conference with process engineers at another location or with NDC's service technicians. The system will be commercially available in January. Pricing will start around $25,000 for an upgrade to existing NDC 6000 and 8000 systems.

OPTICAL INSPECTION SYSTEM

A relatively new optical inspection system for high-quality web products has been adapted from the paper industry for use in flat films and extrusion coatings. Part of the MXOpen product line from Honeywell-Measurex, Cupertino, Calif., the optical detection system uses CCD cameras to recognize defects from dust particles, dirt, gels, insects, or holes. The unit has a 10-kHz scan time. Data can be used by any off-the-shelf graphical interface such as a Windows NT system to generate defect maps. Prices range from about $100,000 to $500,000 depending on the length of the web and the size of particles to be detected.

FASTER PIPE DIE CHANGES

A new pipe die head from Rollepaal USA, Columbia, Md., is designed to reduce changeover times from 2-3 hr down to less than 30 min.

Rollepaal also launched a new multilayer pipe head designed to handle up to 80% recycled resin at rates to 2200 lb/hr.

NEW SYSTEM FOR CORRUGATING PIPE

Single-, dual- or triple-wall pipe in sizes of 50 mm I.D. to 270 mm O.D. can be produced at up to 78 ft/min on the new HD-250/38 corrugator from Drossbach Machinery Corp., which relocated from Guelph to Cambridge, Ont., last month. (Triple-wall pipe requires a special cross head die.) The machine has an improved cooling system and new quick-mold-change capability.

PIPE WALL SCANNER IS A FIRST

New RRS pipe measuring devices from Rollepaal USA are the firm's first rotating ultrasonic sensors. They contain two rotating sensors positioned 180 [degrees] apart. The scanner can be placed directly after the die head, rather than after the cooling tank, providing closed-loop control with response time of as little as 1 min. Three models cover pipe diam. of 20-500 mm.

RUN MEDICAL TUBING OF METALLOCENE PE

A new line of tubing extruders from Harrel Inc., East Norwalk, Conn., is optimized for metallocene polyolefins. A special low-shear screw accompanies a new cutter design that doesn't allow the material to stick to it. The line can make bump tubing and yields output rates similar to rates normally obtained with LDPE.

LOW-COST GRAVIMETRIC CONTROL SYSTEM

The first system from Maguire Products, Inc., Media, Pa., for gravimetric extrusion yield control is said to be simpler than others on the market and cost half as much. It's a batch-type system consisting of a touchscreen PC with proprietary software that communicates with Maguire weigh-scale blender controls.

The drive on each extruder in a system is slaved to its blender controller, which adjusts screw speed. The PC can also control takeoff speed through use of a shaft encoder. The system costs about $4000 for the software and $2000 for a Pentium-based computer

ENHANCED EXTRUSION CONTROL

The MACO 5000EZ is an enhanced version of the MACO 5000 extrusion controller from Barber-Colman Co., Industrial Instruments Div., Loves Park, Ill. It comes with two new analog cards for melt-temperature and melt-pressure control (the latter works by regulating screw speed), plus a digital drive interface and additional preloaded software for functions such as SPC charting and temperature ramp and soak functions. Automated heat start-up requires no operator involvement. Predefined screens and sequence logic can be edited with PC-compatible software. A "Custom" version includes new high-density analog I/O cards designed to provide increased temperature-control capability for blown film operations.

The 5000EZ system is available with any of Barber-Colman's fiat-panel displays. Price is around $15,000. Although the 5000EZ is a 12-slot system, it's available in a lower-cost nine-slot version (Custom 50EZ) and a premium model (5500EZ) with 16 slots.

SCREW GIVES EXTRA MIXING

The new Double Eagle mixing screw for extrusion incorporates what amounts to two of the Eagle mixing sections used on injection molding screws from Westland Corp., Wichita, Kans.

According to chairman Martin Davis, the new screw provides more dispersive than distributive mixing and gives higher shear than the injection molding version. It can be tailored for any resin. He foresees uses in profiles and tubing.

SMALL EXTRUDER LINE

New MN series of air- or water-cooled, grooved-feed extruders from Merritt Davis Corp., Hamden, Conn., is available in 0.75 in., 1 in., and 1.25 in. diam. (all 24:1 L/D) in floor models or pedestal mounted for use as coextruders. The hopper is adjustable to remain vertical when the extruder is angled. All units have AC vector drive, water-jacketed feed throat, and articulated die support for quick changes. Processing rates run 10-70 lb/hr.