Control & instrumentation | machinery feature
Plastic film and sheet comes off the line at enormous speeds these days – making the job of checking thickness and quality ever more challenging. Lou Reade reports
One of the defining attributes of a plastic film is its thickness – so controlling this aspect is of critical importance to film producers. BST has developed a new transmission sensor for
layer thickness and basis weight measurement. The PC16S-wave does not work with ionising
electromagnetic waves, so its operation, transport and disposal do not require national or international permits. With its touch-free absorption measurement procedure in transmission, it measures polymer-based monofilms quickly and precisely. Typical examples of implementation are the measurement of basis weights, measurements of flat web materials, and the control of calenders and flat film extrusion systems. The sensor offers some special characteristics, says BST – such as the ability to account for colorants. For instance, white films are frequently filled with titanium dioxide while black films contain carbon black. These fillers can influence the measurement results of traditional measurement materials, such as X-ray or infrared technology, but the influence is typically negligible with this new transmission sensor, says BST. Compared with sensors with ionising radiation, the PC16S-wave achieves high measurement accuracy of up to 0.05g/m². In addition, it covers a large measure- ment area of up to 2,000g/m². Because its measure- ment method is based on non-ionising technology, this removes the costs of radiation protection. Measurement data, transferred at a sampling rate of 100Hz, is quickly transferred via Profinet, because the sensor is equipped with an open analysis unit from Siemens. That is an advantage for many customers because they are confident in using the programming language of the analysis unit.
www.filmandsheet.com
The thick of it: film thickness control
QC for sheet The Planowave 6000 from Sikora is a non-contact system for measuring the thickness of plastic sheets during extrusion. The non-destructive system is designed for the
measurement of all plastic materials, including PE, HDPE, PP, polyamide and PVC. Innovative millimeter wave technology offers a precise
measurement of the thickness without any coupling mediums and independent of material and temperature of the plastic sheet. Calibration is not necessary. The Planowave 6000 can either be integrated into the
production line directly or used for the final inspection. The sheet is measured via millimeter waves based on the Frequency Modulated Continuous Wave (FMCW) runtime method. A linear moving transceiver continu- ously sends and receives frequency modulated millimeter waves. The thickness of the sheet is defined by the runtime difference. Visualisation of the measuring values is made in real time. The processor system Ecocontrol offers a numeric display of the measuring values as well as a graphic display and comprehensive trend and statistical data.
March 2017 | FILM & SHEET EXTRUSION 13
Isra says that monitoring coating
thickness on optical films ensures
uniformity and product quality
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