Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS have developed an inline inspection system capable of identifying microscopic defects in packaging seals without damaging the pack. The technology uses optical coherence tomography (OCT) to examine the internal structure of seal seams while packaging machinery continues to operate at industrial speed.

OCT is an imaging technique that directs near-infrared light into a material and analyses the reflected signals. The resulting data creates three-dimensional images of hidden structures. In packaging applications, the system can reveal pores, trapped air and sections that have not sealed correctly, helping manufacturers identify potential leakage risks before products leave the production line.

The OCTInline project integrated the technology directly into a packaging machine, enabling continuous inspection at production speeds of up to 25 metres per minute. According to the research team, the system can detect defects measuring as little as eight micrometres. Achieving this level of precision required careful control of exposure time, depth of field and film movement, as even minor vibrations can affect measurement accuracy.

Reliable seal inspection is becoming increasingly important as brands and converters move towards recyclable mono-material films. These structures can simplify recycling compared with conventional multilayer laminates, but they may also be more sensitive to sealing conditions. Small variations in temperature, pressure or equipment performance can create defects that are difficult to detect using conventional visual inspection.

By monitoring every seal in real time, the OCT system could give packaging producers greater confidence when introducing new materials. The technology may also reduce the need for destructive sample testing, where selected packs are damaged to confirm seal integrity.

Earlier detection allows manufacturers to correct process settings before large quantities of defective packaging are produced. This can lower scrap rates, reduce material consumption and prevent products from being packed in compromised formats. The inspection data can also indicate when sealing tools are wearing down or when pressure and temperature settings are drifting away from the required range.

A demonstration system has been operating at machinery specialist Kallfass Verpackungsmaschinen since July 2026. Beyond flexible packaging, Fraunhofer believes the same technology could support quality assurance for coatings, ceramic components, medical applications and additively manufactured parts. For packaging producers, however, its immediate value lies in combining microscopic inspection with uninterrupted industrial production.