How many times has everyone heard the complaint that commercial rheometers and melt indexers give results that simply have no relation to how the plastic performs in the real world of extrusion or injection molding? Well, you won't need to hear that any more. The Harrel VT-600 VISCOTRUDER slit die rheometer gives values of viscosity and intrinsic viscosity vs. shear that are completely compatible with real world conditions because the data is generated on a real extruder operating under real world conditions!
FEED: You won't have to worry about feed problems impacting your data either. The Harrel VISCOTRUDER will handle full diameter pellets, rounded or cubical, or even regrind.
FLOW: Measurement of viscosity with a capillary rheometer depends above all on a highly accurate determination of the volume of polymer flow. An extruder makes a remarkably poor source for polymer flow, as the output of a typical screw type extruder will change approximately 10-15% per 1000 psi change in the back pressure. And, of course, the pressure has to be changed over a wide range to make meaningful measurements.
The Harrel VISCOTRUDER, therefore, doesn't use just an extruder. It uses a rugged 1" Harrel TIGER series GEARTRUDER(R), with a precision melt pump having a differential pressure controller. The DIGIPANEL(R) controls not just the input pressure to the pump but also the differential pressure across it, to yield 0.1% stability of plastic flow!
SPEED: But a metering pump in turn is no good unless the rotational speed is held constant. Harrel is, of course, a pioneer in the field of digital drives, so the metering pump is driven by a Harrel DIGISYNCH(R) drive with an inherent stability of 0.001%.
COMPUTATION OF VISCOSITY: The computational module which does the viscosity calculations for the VISCOTRUDER is located in the DIGIPANEL controller. The flow of the plastic is measured, along with the pressure drop in the die path. The module then calculates the shear rate, the shear stress, and the viscosity. This produces one point on the curve of viscosity vs. shear. In the case of appropriate polymers, it also makes it possible to calculate intrinsic viscosity.
SCANNING THE RANGE OF MEASUREMENTS: With a manually operated system, the operator would now have to modify the conditions in the instrument and repeat the measurement. With the VISCOTRUDER these changes are made automatically. The limits over which the measurement is desired are set in advance, and the DIGIPANEL automatically varies the operating conditions over the range specified, taking the appropriate measurements as it goes.
THE DISPLAY: Convenience for the operator is one of the VISCOTRUDER's strongest points. Instead of a simple digital readout, all parameters for the operation of the instrument, and all results, are displayed on a 14" full color display! Operating parameters are keyed in on the handy keypad right beside the display.
THE DIE: The slit die is a special Harrel unit designed with an eye to elimination of all possible sources of error. Standard forms have L/D ratios of 15:1, 20:1, or 30:1. Other ranges are available on special order.
PRINTING: The CP-603 single line SQC Module is a most useful accessory to the VISCOTRUDER. This unit not only prints out the data that one sees on the CRT screen but also does a great deal more reduction of the data into useful form:
An even better solution is the CC-620 Central Control and Management Console. This unit performs all the functions of the CP-603 and in addition provides total control and management, and total SQC, for all extrusion lines in the plant.
OTHER USES: One of the corollary advantages of the VISCOTRUDER over conventional rheometers is that the VISCOTRUDER can be quickly and easily converted to a versatile 1" Harrel TIGER series GEARTRUDER for general purpose use around the plant at any time it is not being used to measure polymer viscosity.
For full details fill out inquiry form or call Harrel at (203) 866-2573
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