Foil seals on plastic lids checked for integrity

Engineers at vision systems integrator Olmec-UK (Barton-Upon-Humber, UK) have built an inspection system to check the integrity of the foil seal on the plastic lids that are used to seal a wide range of glass and plastic containers in the food, healthcare and pharmaceutical industries.

The foil seals, which are used on a range of products from milk bottles to sauces such as ketchup, powdered drinks and containers of tablets, provide an air-tight seal to protect against contamination, humidity, tampering and leakages.

The challenge faced by the Olmec engineers was that they were required to image the highly reflective foil material at high speed while ensuring that the system would detect all the possible defects as well as measure the depth of the foil inside the lid.

The vision system they developed addressed these issues by illuminating the foil from different directions and imaging the foil using three cameras positioned at different angles to identify different types of defect. During the inspection process, the lighting of the foil material is sequenced to enhance the types of defects while the three cameras capture nine individual images of each lid in 48 milliseconds.

The system software then analyzes the images to check for defects including tears and blisters in the foil, dents and creases that cause seal voids, and whether the foil is missing or delaminated.

The vision system developed by Olmec has been integrated into complete quality control station that can not only inspect the foil seals but also reject any defective ones.

-- Dave Wilson, Senior Editor, Vision Systems Design