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Downstream equipment for precision extrusion.

Downstream Equipment For Precision Extrusion

Extruders of small precision tubing and profiles - and possibly wire - will be interested in several product introductions from a pair of recent trade shows. A half-dozen equipment suppliers introduced new gauging devices, controls, cutters, and other downstream equipment for extrusion at the Medical Design & Manufacturing show in N.Y.C. Incorporation of statistical process-control (SPC) reporting is a feature of several of the new controls packages. And a supplier of West German gauging equipment was introduced to the U.S. market at the SPE ANTEC in Dallas.


Outstanding accuracy in feeding, measuring and cutting very fine, flexible, and hard-to-handle medical tubing is claimed for the new MED/1000 cutter from G.F. Goodman & Son, Inc., Warminster, Pa. Sales & Marketing v.p. Robert J. Butts cites these examples from actual customer production:

* Cutting 18-mil O.D. polyolefin tubing at 20 ft/min into 1-in. pieces with [+ or -] 5-mil accuracy;

* Cutting 18-mil PVC tubing at 100 ft/min;

* Cutting 60-mil O.D. silicone tubing at 65 ft/min into 4-in. pieces at [+ or -] 30-35 mils.

The on-demand cutter handles tubing up to 1/4-in. O.D. at rates up to 600 ft and 1000 cuts/min. It uses the proven Vac-U-Torq vacuum clutch/brake, along with a wheel-type digital encoder for measurement accuracy. Optional pinchroll feed-assist (not a puller) with a special bushing guides tubing gently without crushing it, according to Butts. He also notes the unit's simple and compact design, clean-room compatibility (no particulate generation), easy interchangeability of pinch rolls and cutter bushing to handle different products, and an economical price starting around $10,000.


Another unusual accomplishment for thin-wall tubing and profile production is claimed by Wayne Machine & Die Co., Totowa, N.J. Its new Yellow Jacket vacuum sizing tank reportedly achieves extremely stable vacuum levels, especially at low vacuum, which is hard to do, says operations manager Joseph V. Scuralli. Unlike standard venturi systems, this unit does not use the "bleed-in" method of vacuum control with make-up air, which greatly reduces noise, internal air turbulence, water splash and sensitivity to ambient atmospheric-pressure disturbances, according to technical manager Gary M. Lischak. This tank uses a proprietary electronic control instead of a mechanical valve. A simple potentiometer dial allows easy vacuum adjustment. The tank comes in modular 2-ft size increments and typically costs about $14,000.


Real-time data logging and SPC functions, as well as bidirectional communications capability, are key features of the new Usys 1000 Universal Processor/Controller for use with diameter gauges from Zumbach Electronics Corp., Mt. Kisco, N.Y. The multi-tasking system measures, displays, monitors, controls, collects SPC data, prints out reports, and communicates to a host computer simultaneously. It has a flat membrane keypad, product library for 450 parameters (30 products), and multiple RS232 ports. An eight-character LED displays product dimension, control signal, and error codes. Product deviation is shown on a red bargraph display. A backlit LCD displays simple prompts, messages and commands, and a visual alarm for tolerance limits is also included. Price of the unit, not including measuring heads, is $6400. The unit can be upgraded into the Usys 5000, an expanded data acquisition system that can simultaneously process data from several measurements in complex manufacturing procedures.

Automatic SPC is also a feature of the new Model 182-38 controller from LaserMike Inc., Dayton, Ohio. This system has two independent control loops - typically, one is for O.D. and the other either for I.D. or wall thickness. The controller utilizes an optical laser scanning micrometer for O.D. measurement and a gamma backscatter gauge from NDC Systems, Monrovia, Cal., for wall thickness. Control of air pressure and hauloff speed may be manual or automatic, the latter in either proportional or adaptive mode. Adaptive control allows the loop to self-tune the control parameters to compensate for characteristics of the extrusion machinery and product being manufactured.

The system has a small CRT screen that displays real-time SPC X-Bar and R charts and histograms for each parameter measured or calculated (I.D., O.D., and wall thickness). Hardcopy reports can be printed out, and bidirectional communication with a host computer is also provided.

Interesting, convenient features are an on/off button to start/stop collection of SPC data (useful during start-up, for example), and pushbuttons for "Clear Data" and "SPC Print." What's more, a pair of alarm lights warn the if either product measurements or X-Bar/R calculations exceed [+/-] 3-sigma SPC limits. Price starts at $34,000.

SPC software has now been incorporated into the full line of compact, single- and dual-axis infrared O.D. gauges from Contrologic Inc., Blue Bell, Pa. an 18-month-old company dedicated to extrusion gauging. This new software integration allows diameter and ovality measurements to be transmitted in real time to a personal computer for automatic statistical calculation and display, with no operator intervention. Up to 16 Contrologic gauges can report to one PC running a single SPC package - either QA/S from Paul Hertzler & Co. Inc., Goshen, Ind. Penton's Quality Alert2, or PQ Systems' SQCPack. The QA/S package is available directly from Contrologic or from Hertzler.

Also new from Contrologic is a PID closed-loop control module for its gauges. This slim, user-installable module includes programmable PID constants and deadband (which the controller ignores to prevent overcontrol) and three output functions: motorized potentiometer or time-proportional relay contact, 0-10 v analog, and digital serial output to a drive control. At $695 for the add-on module and $3695 for a complete gauge/controller system, the company says this is very low cost for a PID feedback loop controller. Other Contrologic modules include an analog option for simultaneous O.D. and deviation output, an alarm-limit module, and serial-printer module. All Contrologic gauges use an infrared light source that never needs replacement or maintenance, according to sales & marketing v.p. Michael A. Stroz.

An infrared gauge with a fiber-optic sensor that attaches to the die is new in the U.S. from Profitec of West Germany. Sold here by Actual Plastics Technology Corp., Bridgeport, N.J., the Profitec 01 gauge measures O.D. or critical dimensions of profiles and tubing on-line and can adjust hauloff speed for closed-loop control. It's said to be very easy to use. The gauge head has two fiber-optic cells, one for measuring and one for a reference, so that it self-corrects for presence of fumes or dirt accumulation. Once the sensor becomes 50% obscured, an alarm signals it's time for cleaning. Price is approximately $20,000, and an optional printer adds approx. $5,000.


New software for off-line programming of puller/cutter parameters to produce so-called "bump" tubing (catheter tubing with intermittent thicker sections) is available on an IBM-compatible PC disk for $3000 from Versa Machinery Co., Somerville, N.J. This self-prompting "Advanced Bump Control" (ABC) program starts with a drawing of the bump-tubing profile and enables the user to program the sequence and profile of puller-speed and air-pressure changes needed. The software then will simulate the resulting tubing profile to confirm the correctness of the program. Once completed, the program can be downloaded to Versa's Accupull digital-drive puller/cutter. Incidentally, Versa has a new touchscreen control for its Accupull unit, which can store 12 operating programs.

A different sort of new offering from Versa is a footpedal-operated, pneumatic flare tool for flaring the ends of medical-tubing sections to receive fittings. The V-type jaws on the tool produce a tapered funnel entry, which is said to prevent the creasing that can be produced by parallel-jaw flare tools. This product, designed to prevent fatigue of workers' hands, costs $800.

PHOTO : Simple, compact design and ability to feed, measure and cut hair-thin, flexible tubing accurately at high speeds are key features claimed for the new MED/1000 cutter from G.F. Goodman & Son.

PHOTO : Maintaining stable, low-vacuum conditions is a difficult task that's said to be mastered by this new vacuum sizing tank from Wayne Machine & Die.

PHOTO : A slim, user-installable module now permits upgrading Contrologic's infrared diameter gauges to PID closed-loop control. Capability for SPC reporting to a PC is now built in.
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Author:Naitove, Matthew H.
Publication:Plastics Technology
Date:Sep 1, 1990
Previous Article:CIM made simpler.
Next Article:News in medical-grade plastics.

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