Testing the Melt Index of Plastic Granulate

Components manufactured from thermoplastics need to satisfy certain criteria. Consequently, quality assurance starts by determining the flow rate of granulate after delivery. Developed specifically for this purpose, the portfolio of ZwickRoell testing instruments ranges from a manual tester to Aflow, a completely automatic comprehensive solution with electromechanical force control.

The flow features of a thermoplastic are described by the melt index. Depending on the test method, a determination can be made of the mass per unit of time (MRF measurement) or the volume per unit of time (MVR measurement). A variety of testing instruments for determining melt rates is available from ZwickRoell in Ulm, Germany.

The portfolio comprises Cflow, a small, manually operated tester, the modular Mflow, which includes classical load weights, and the fully automatic, comprehensive Aflow, embodying electromechanical force control. The latter was designed to operate at exceptionally high specimen testing rates and specially calibrated to determine volume and melt flow rates to Methods A, B, C and D. All established standards and techniques are supported, including ISO 1133, ASTM D1238 and ASTM D3364.

Mflow and Aflow Instruments

One of the Mflow and Aflow instruments’ outstanding functions is the ability to detect possible air bubbles in the plastic melt. Air bubbles momentarily enhance piston speed, leading to a distorted flow rate. ZwickRoell testing instruments permit high-resolution time and travel measurement, which thus allows modifications to piston speed to be diagnosed automatically. This means that certain extrudates can be eliminated from the evaluation process, which helps to prevent mistakes in flow-rate calculation.

The user is also helped by the APC (Adaptive Process Control) function, which calculates the speed of the piston immediately prior to the actual measuring process commences. Using this data, the system can select the optimal type of control – travel or time-controlled – and can thereby calibrate the best possible measurement interval for the anticipated MVR value.

An easy to use, workflow-based touch operation permits the user to pass effortlessly between PC and instrument. The melting procedure and behavior of the melt during evaluation can be tracked in real time, both directly on the instrument and using the ZwickRoell testing software.

Mflow Extrusion Plastometer in All Models

The modular Mflow extrusion plastometer is utilized to assess the melt flow rate (MFR) and volume flow rate (MVR).

Fully Automated Aflow Extrusion Plastometer

The extrusion plastometer supports all globally common standards and methods for melt flow testing, including ISO 1133 and ASTM D1238 according to Methods A, B, C and D.

This information has been sourced, reviewed and adapted from materials provided by ZwickRoell Ltd (UK & Ireland).

For more information on this source, please visit ZwickRoell Ltd (UK & Ireland).


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