QUALITY CONTROL | TECHNOLOGY


Measurement moves from lab to line


The benefits of inline metrology and control can be felt in many areas of processing such as melt


flow, colour and moisture content, as well as in product development. By Jennifer Markarian


Inline (sometimes called online) measurement is increasingly important in plastics compound and masterbatch production. “There is a clear shift from purely lab-based testing toward inline and online testing in several specific areas, driven by higher material variety, shorter runs, and tighter tolerances,” said Tim Haake, General Manager at Goettfert. “As the variety of compounds and masterbatches grows, production runs become shorter and changeovers more frequent, leaving far less time to rely on batch sampling and offline lab results. For quality control, knowing quickly when material goes off spec is critical, and only online testing can provide that immediate feedback. In this environment, continu- ous measurement is not just a convenience; it becomes essential for catching deviations in real time, reducing scrap, and ensuring that every short run still meets its intended performance targets.” Haake said that rheological and flow-related


measurements, in particular, are moving strongly toward inline solutions. “Properties like viscosity, melt index, shear behaviour, and pressure-flow relationships are critical for process stability, yet they are also highly sensitive to small formulation or temperature changes. Instead of waiting for lab results from a capillary rheometer or melt indexer, processors increasingly want inline systems on extruders or compounding lines that continuously


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monitor flow behaviour. This allows operators to see drift immediately and correct it before a whole short run is lost.” More detailed information is increasingly


sought, and single-point measurements are no longer sufficient, said Haake. “Customers are asking more detailed questions about processabil- ity, stability, and end-use behaviour, which means testing has to become more targeted, more frequent, and more application-specific.” Goettfert offers online capillary rheometers, and


its latest instrument is a Rotational Online-Rheome- ter. This inline oscillatory rheometer provides continuous, detailed characterisation of the viscoelastic properties of polymer melts, which adds the capability of viscoelastic and structural insight to inline testing. Haake explained: “By applying oscillating


deformation over a range of frequencies, these systems reveal subtle changes in molecular architecture, such as branching, networking, or changes in molecular weight distribution. Because they operate at relatively low deformation rates, they are highly sensitive to structural differences, making them ideal for answering ‘structure’ questions – how a polymer is built and how that structure affects its elastic and viscous response.” He continued: “Users no longer have to choose between lab-based structure analysis and inline


August 2026 | COMPOUNDING WORLD 17


Main image: Inline systems measure deviation while the process is running


IMAGE: SHUTTERSTOCK


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