PROCESS CONTROL | INLINE MEASUREMENT
Right: A ColVisTec inline probe installed in the die to provide fast insight into the extrusion process
proper characterisation of a complex multi-parame- ter system, according to Eker. “Quality relevant process parameters, as well as their process windows, can be determined easily. For this pur- pose, ColVisTec offers ReTA (Residence Time Analysis), a special and unique software tool. With this software, residence times are detected quickly and with fine resolution, which avoids the collection and complex analysis of samples and long waiting times,” he says. “ReTA analyses residence times (dwell) that are
measured in seconds with the InSpectro X. After three mouse clicks, all residence time relevant data are calculated and displayed in figures, as well as graphically. This fast method allows, for example, the optimisation of the screw configuration for a specific recipe, determination of process windows for speed and throughput, and determination of screw wear,” Eker says. The ReTA software allows optimisation of the
extruder and the process to be achieved quickly and easily, Eker says, adding that the InSpectro X inline technology can also provide extruder application real-time information about the current status of the process via the colour of the processed product, measured directly in the polymer melt.
Continuous need According to ColVisTec, any continuous production process requires continuous monitoring of product quality but inline process monitoring in extrusion is particularly relevant because many different formulation components must be produced homogeneously and constantly over extended periods. Measuring technologies that only record machine data and do not provide information on the processed product are not sufficient as the quality demands of customers are increasing and the costs —both in time and money — of off-spec production must be avoided. The company highlights that a customer recently developed a new formulation for a product, as well as the process for its production, using inline measurement and inspection. “The customer decided to use a premix of two components in order to use a single feeder. The expectation of this approach was that it would provide a better and more homogeneous product. We supported the customer in this project with inline measurement in the extruder using InSpectro X and a reflectance probe. InSpectro X quickly showed that segrega- tion was taking place. The material was particularly inhomogeneous ,” says Eker. “Based on rational data, we proposed that the two components of the formulation should be
28 PLASTICS RECYCLING WORLD | November/December 2023
introduced through two feeders in a split feeding process. This resulted in a consistent material and a robust process,” he says. AI is attractive as a potential tool in terms of inline
measurement and inspection. Eker says that any AI-based algorithm requires relevant and reliable data. In a continuous process, a lot of machine data — for example, pressure, temperature, speed and throughput — has been available for quite some time and he encourages its use. However, he emphasises that quality data, such as viscosity, dimensional data, and homogeneity, as provided by ColVisTec’s InSpectro X, raises this to another level and allows a batch of material to be produced and documented from the first to the last pellet. Continuous measurement collects and stores a
lot of data, so it is necessary to be able to analyse it quickly and in detail to gain knowledge from it. For this purpose, ColVisTec has developed RedLog, a new software product that was intro- duced at the Fakuma 2023 trade fair in Germany and was shown at the Compounding World Expo in Cleveland in the US in November. RedLog presents an overview of measurement data from a whole year and is able to zoom into a single raw data file (if required) with an emphasis on data visualisation of an individual batch. Various options allow 2D and 3D representations that can also be graphically and number based. According to German company Sikora, which manufactures inline pellet inspection systems, the market for inline measurement and inspection equipment is being driven by demand for high performance technical plastics, in particular for the medical, aircraft and automotive industries. “These require the highest quality standards, as well as reli-
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IMAGE: COLVISTEC
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