Zwick's new Aflow extrusion plastometer offers
significant improvements in Melt Index Measurement

Zwick's new Aflow extrusion plastometer was presented to industry specialists for the first time at the 18th testXpo international testing technology forum 2009. "With this instrument we have demonstrated that new developments leading to significant improvements are possible even for really classical methods such as MFR/MVR determination," states Florian Liebert, who as product manager oversaw development of the new plastometer.

A glance at Aflow confirms that it does indeed represent a new direction in melt index measurement. Designed for 50 kg test loads, the instrument presents a compact appearance. Florian Liebert explains: "This is basically because the instrument uses state-of-the-art force control in place of the usual individual weights. We have been installing force and position-controlled drives in testing machines at Zwick for many years and they are also commonly employed in rheometer construction. It seemed logical to apply this proven technology to high-quality extrusion plastometers as well."

Refer to the picture: State-of-the-art force-control, improved control of test load, pneumatic cleaning device and automatic parameter control are just a few of the key factors in the high level of operator convenience offered by the new Zwick Aflow extrusion plastometer.

The advantages of this technology are that it makes melt index determination significantly easier and more reliable. It offers the option of controlling the start position specified in the standards by means of superimposed force and speed control. At the start of measurement the instrument identifies the amount of polymer in the extrusion barrel and determines independently, on the basis of pre-set limit values, the load to be used in the pre-heating phase. This is a crucial advantage when polymers with unknown MFR are being tested, and also when operators have not adhered precisely to the specified charge quantity.

Load application via electromechanical drive provides greatly improved load control during the test. Weight application in classical instruments almost always involves percussive loadings; these are greatly reduced with Aflow. Multi-stage tests in particular, i.e. tests with various test loads, are largely impact-free using this instrument. Residual material at the end of the test can easily be extruded using the maximum test load of 50 kg, saving testing time.

The new Aflow is equipped with a pneumatic device for cleaning the extrusion barrel. This is a simple and fast two step process - the operator positions a cleaning pad and presses a button. Admittedly many polymers require the procedure to be repeated several times, but it is still considerably easier than manual cleaning.

This device can also be used for pre-compacting the test material directly after charging. The advantage is that pre-compacting is performed in a uniform manner, reducing operator influence and giving more consistent results.

Aflow has all the features of Zwick's existing product range, including automatic parameter control (APC), by which the optimum test parameters are determined and applied during the test.  It also includes automatic bubble detection, which eliminates measurements distorted by air-bubbles.

The temperature in the extrusion barrel is generated by four heating elements, allowing Aflow to achieve a temperature accuracy of better than + 0.3°C over the relevant area of the barrel.

The instrument is usually controlled via a PC with testXpert® II test software. Up to six Aflow and Mflow instruments can be managed and controlled by one PC. Highly operator-friendly stand-alone operation is also available, however.

"This instrument has been developed for testing-laboratories with a very high throughput, where testing is carried out continuously in three-shift operation. Here every movement counts and equipment must be highly robust and reliable in operation," is Florian Liebert's summary of the development concept behind the new product. It will also appeal to customers who simply appreciate the operating convenience which the new Aflow offers.

State-of-the-art force-control, improved control of test load, pneumatic cleaning device and automatic parameter control are just a few of the key factors in the high level of operator convenience offered by the new Zwick Aflow extrusion plastometer.

New testXpert^® features for enhanced convenience and reliability

Zwick Roell's testXpert®  sets the standard for intelligent materials testing by providing a uniform operating concept for all applications. It has now been further enhanced by a range of new features, seen at testXpo 2009 international testing forum.

Operator interface for touch-operation
The new testXpert® II touch interface provides interactive operation via a PC mounted directly on the testing machine and adjustable for operator comfort. Navigation optimized for touch-PCs combined with efficient parameter input via an integrated alphanumeric panel provide a significant reduction in operator workload, particularly for simple tests.

Speech output
The ideal complement to touch-PC operation, testXpert II speech output actively guides the user through the test sequence.

From the start of the test the operator receives all essential information on the test sequence and is actively prompted to any required user actions, such as 'attach extensometer', and can also be informed of results determined online. Easily integrated customized texts provide operator prompts for defined actions, even after the test (e.g. guidelines for disposal of specimen remains).

Pictured above: The new version of test software testXpert® II V3.2 with user interface for touch operation provides efficient, convenient interactive operation (left). A new testXpert® II V3.2 software function enables visual display and storage of the test assembly used for a test, plus specimen-specific images - the entire test sequence (right).

Fast configuration through intelligent default allocations
Operation has been greatly simplified for many testXpert® II functions by intelligent, logical default allocations, including generating reports in PDF format with one mouse-click, specimen and series-specific default reports and fully pre-configured export interfaces for Word, Excel, ASCII data export and long-term evaluations. Naturally all default allocations can be quickly and individually matched to customers' individual requirements.

Materials testing visualization
This new function enables a visual record of the test arrangement used for a particular test to be stored via a photograph or video. These images and videos are generated with one click of a button and are administered in their own layout, which is integrated into the Test Program. This provides the user with important information on the required test arrangement, particularly useful when a wide range of test arrangements are in use.

It is also possible to store specimen-specific images, for example if the failure image is also to be documented. Again, one button click is all that is needed for automatic recording and allocation to the specimen.

The new version also enables videos from high-speed cameras (as well as from web cameras and camcorders) to be integrated in testXpert® II and synchronized perfectly with the curve graphics.

Automatic SMS dispatch
It is often necessary for the operator to be notified of the end of a long-term test. Arranging an automatic SMS (with individual text) is easy with the new 'SMS message' option: simply input the telephone number and required text into the prepared parameters.

Electronic signature
The electronic signature is ideal for use with the Expanded Traceability option. The medical industry in particular requires verification of test parameter changes and authorization of changes. In this case the electronic signature feature replaces the signature on a document with a digital signature in testXpert® II, enabling the customer to meet all requirements for fulfilling FDA 21 CFR Part 11.

Option: universal connection of HBM measurement amplifiers 
This option allows connection of HBM MGC+, Spider and Quantum X measurement amplifiers. All channels are synchronized, with a data transfer rate of up to 2000Hz, allowing data from each channel (e.g. from strain gages) to be read into testXpert II.

testXpert® II and Windows 7
The current version of testXpert® II  V3.1 is released for the new Windows 7 Microsoft operating system with immediate effect, allowing customers to change directly to Windows 7 if required.

Mflow extrusion plastometer: all weights securely contained in the instrument

Zwick's Mflow extrusion plastometer allows melt index values MFR and MVR to be determined quickly and conveniently. The system features modular design and functions such as travel measurement can be retrofitted as and when required, while an innovative weight selection unit provides enhanced operator safety and convenience.

Different weights are used in extrusion tests (MFR, MVR determination) depending on the polymer being tested. The individual weights must then be positioned manually by the operator. This is a laborious and potentially hazardous procedure, as a weight may fall and injure the operator.

A new development from Zwick has solved this problem. Now available for the modular Mflow extrusion plastometer is an auxiliary unit which provides program-controlled positioning and removal of the test weight in use. Manual selection is also possible by simply removing the selector and re-inserting it in the desired position.

The instrument contains test weights specified in ISO 1133 up to 21.6 kg, arranged so as to eliminate the possibility of error. Cleaning the instrument is no problem thanks to an easy action swiveling unit.

The instrument can be controlled via integrated computer electronics or a PC as required. The innovative automatic parameter control  ensures reliable measured values, even with untrained operators. For further information, view website: www.zwick.com   

Zwick's new Mflow extrusion plastometer allows melt index values MFR and MVR to be determined very quickly and conveniently.