Inline inspection system for detecting sealing seam defects




  • High quality requirements for sealing seams to ensure product safety
  • Highly fluctuating processing properties due to the process or packaging material during heat contact sealing
  • Very narrow process window for sealing recyclable films
  • No suitable inline inspection procedures for continuous seam inspection

Research results

  • Method for the prompt detection of critical seam defects in packaging
  • Demonstrator of an inspection system for inline quality control of sealing seams in packaging machines
  • Non-destructive, fast inline inspection of sealing seams without reducing machine output


  • Locating seam defects to eliminate faults
  • Traceability of packaging with defective sealing seams
  • Reliable quality assurance
  • Increased efficiency and sustainability by reducing rejects
Sample foils tested on the web transport test rig.
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Increased requirements for heat contact sealing of monomaterials


The sealing of flexible packaging for food, cosmetics, pharmaceutical and technical products predominantly involves heat contact sealing. Ensuring product safety places the highest demands on the quality of the sealing seams, in particular their tightness and freedom from contamination. However, insufficiently adjusted sealing parameters, air pockets, wrinkles and contamination in the seam area can lead to sealing seams in the production process that do not meet quality standards.

The increasing replacement of multi-layer composite films with recyclable monofilms in the interest of a circular economy is increasingly leading to problems with heat contact sealing due to narrow processing windows. This increases the need for continuous seam inspection in production to prevent the transport of defective products to the consumer and to reduce rejects by detecting the defects at an early stage while the products are still with the producer.

Seam inspection methods used to date do not meet these requirements, as they are usually only suitable offline for random samples and the packaging is destroyed in the process. Inline methods used, such as CO2 test gas tests, again do not achieve the speed required for seamless testing of all packages produced. In addition, most methods do not allow localization and classification of defects based on features to evaluate critical defects.


Inspection system for timely, end-to-end inline seam inspection during ongoing processes


The aim of this research project is therefore to develop a novel inspection system for 100% continuous inline inspection of sealing seams. Optical coherence tomography (OCT) is used as a target-oriented method for defect detection. This makes it possible to detect and quantify defects using three-dimensional joining seam images. Within the scope of the project, the OCT method and the hardware for measurement data collection will be further developed for application in the inline quality control of sealing seams and a demonstrator system will be integrated into a packaging machine in order to carry out a validation of the system under practical conditions. This will also ensure that the system can be applied in production operations.


Quality assurance, resource efficiency and the basis for adaptive sealing processes 


By using the inline inspection device, manufacturing companies can ensure prompt, completely end-to-end inspection of their sealed film packaging and thus its quality assurance without restricting machine output. The inspection system thus helps to increase product safety for consumers and improve process efficiency. At the same time, the option to detect faulty packaging during the packaging process and to reintroduce the packaged goods back into the process through repackaging significantly saves resources.

In addition to the immediate benefit within the packaging process, the system is a valuable tool for increasing the automation of the packaging process. It enables process data to be collected and internal process-specific databases to be created for process analysis purposes. As a result, it creates the starting point for developing adaptive sealing processes through prompt defect detection and intelligent adaptation of the process parameters in the sealing process.

If you have any questions or would like more information about our research project, please feel free to get in touch!


Additional project information


Project duration July 1, 2022 to June 30, 2025
Cooperation partners Fraunhofer Institute for Ceramic Technologies and Systems IKTS,
Kallfass Verpackungsmaschinen GmbH,
IMM electronics GmbH
Grant number 13N16375
Project sponsor/Grant authority VDI Technologiezentrum GmbH / German Federal Ministry of Education and Research (BMBF)