The role of x-ray inspection systems in glass packaging

Paul King, head of sales at Mettler-Toledo Safeline X-ray, says a single shard of glass in a product can have devastating effects.

A glass- packaged product

He says inspection systems are vital on glass production lines. Such systems ensure clean, contaminant-free packs reach the retail supply chain.

Glass contamination can occur accidentally on a production line in many ways. There could be breakages during the cleaning process, on the line because of conveyor vibrations or back-pressure, or during the filling process due to misaligned filling heads striking the top of containers. Over tightened containers can also cause breakages.

‘Glass is the most challenging packaging format to inspect, primarily because the main contaminant associated with it is glass itself – which is the same material density as the packaging. The size and shape of containers can add to the complexity of inspection, as the base, sidewalls and neck of containers can cause blind spots, where the packaging itself has the potential to mask a contaminant.’

Unusually shaped containers can present themselves to the x-ray system in different orientations and have no fixed points, which can lead to false rejects as the x-ray image keeps changing. The product within can also cause what is known as ‘product effect’. Products with a high salt content – such as brined items for example – can affect the level of x-ray absorption and system sensitivity, which may also lead to false rejects.

To overcome these challenges, x-ray systems have been designed and developed specifically for this application. X-ray is the only product inspection solution capable of detecting glass contaminants in glass containers and does so by measuring the differences in x-ray absorption throughout the container. The latest x-ray technology inspects all areas of a container by sending x-rays through the base area, while simultaneously inspecting through the sides. This provides all-round inspection and the crown of the container appears flat. This means blind spots are effectively removed. The beam passes level with the shoulder of the container (below the threads and cap) and produces a far less complex image, enhancing detection capability. The angle of inspection also enables exceptional, full-height fill-level inspection at high speeds.

X-ray systems can be adjusted to suit a wide range of container sizes via full-length guide rail systems. This ensures smooth product handling and repeatable product changeovers, which are vital to ensure productivity levels are at a maximum.

For manufacturers producing products in glass containers, x-ray systems are a must-have on production lines. There are a number of variables to be considered to achieve the optimum configuration. By working with an expert partner, it is possible to ensure that glass contaminants are detected and rejected effectively – safeguarding brand reputation and, most importantly, the safety of consumers.