• 30 JAN 18

    Flexible Metal Detection Systems Make Product Changeovers Effortless

    As competition for retail shelves intensifies, it’s important that production lines are as flexible as possible to allow manufacturers to respond to sudden changes in market demand, whether caused by fluctuations in consumer habits or holidays, or the introduction of new or limited edition products. Leanne Peasnall, Head of Marketing at Mettler-Toledo Safeline Metal Detection, explains how the latest metal detection systems are designed to enable straightforward product changeovers, with minimum downtime, to help food manufacturers respond to changes in consumer demand as quickly and effectively as possible.

    Food safety is an overarching concern for consumers, retailers and governing bodies alike.  Manufacturers must therefore balance their need for production line flexibility with a consideration for consumer welfare. Product inspection systems, including the latest metal detectors, are designed to help manufacturers comply with regional and global food safety regulations, as well as Global Food Safety Initiative (GFSI)-approved standards such as the British Retail Consortium (BRC) Global Standards and the International Featured Standards (IFS). The ability to meet food safety standards and retailers’ code of practice requirements is essential for manufacturers wishing to export their products to lucrative global markets and grow their brand.

    Tuned or Multi-Simultaneous Frequency?

    To achieve high product inspection precision, a metal detector’s inspection frequency must be ‘tuned’ to optimise detection sensitivity for a specific product type. If the food product is dry, then for optimum detection sensitivity, the metal detector should be set to its highest frequency. However, foods with high moisture or salt content, or those packaged in metallised film, have traditionally proved challenging to inspect as they can produce what is known as ‘product effect’ – an electrical signal that can reduce a metal detector’s ability to detect very small pieces of metal contaminant, resulting in false rejects at higher sensitivities.

    For a production line processing an array of products, the metal detector must allow straightforward retuning of the detection frequency to facilitate changeovers. Tuned frequency metal detectors allow manufacturers to easily set up the metal detection system to detect contamination in new products. Such systems are programmed to allow one, two or three frequencies to be used to meet specific production line requirements.

    For manufacturers producing a variety of different product types, or where the product’s physical state may vary, the metal detector system must be able to effectively eliminate the active product signal to achieve sensitivity levels that would be associated with the inspection of ‘dry’ or non-conductive products. The addition of Product Signal Suppression technology allows the latest metal detection systems to modify the product signal during product setup so that it appears to be similar to that of a non-conductive product. Complex software algorithms can then be applied to every product that passes through the metal detector, so as to mimic the product signal captured during the auto set-up routine. This allows false triggering incidents due to inherent variations in challenging products to be virtually eliminated, minimising product waste and boosting manufacturing Overall Equipment Effectiveness (OEE) to reduce operating costs.

    Consideration should also be given to due diligence to ensure contaminated products are properly removed from the line. This is achieved by incorporating a fully-automated rejection system with multiple pack sensing and control devices. The automatic reject mechanism is controlled via input from both the metal detector and the conveyor pack sensors, enabling contaminated products to be efficiently removed without stopping the production process. In the event that a contaminated pack hasn’t been removed, a reject confirmation sensor reports this to the system and an alarm is triggered, providing full failsafe functionality.

    Further guarantees of accurate rejection are provided by a secondary reject check sensor, located further along the conveyor belt, which signals a fault should the rejection mechanism fail or the pack in-feed sensor malfunction. If there’s any failure, an alarm is activated, stopping the machine. All activity is monitored and documented within the metal detector, providing reassurance that sufficient control measures have been taken to ensure product safety.

    Production line flexibility is a must-have for food manufacturers keen to grow. By combining optimum detection sensitivity with simple product changeovers, the latest metal detection systems support such flexibility and can play a key role in helping food manufacturers to safeguard new products, as well as comply with international food safety standards.

    Leanne PeasnallAbout the Author

    Leanne Peasnall is Head of Marketing for Mettler-Toledo Safeline Limited, based in the UK. She has 11 years’ marketing experience across multiple sectors and extensive knowledge of metal detection technology applications in the food and pharmaceutical industries. Leanne holds a Bachelor of Commerce in Marketing and has been a member of the Chartered Institute of Marketing since 2007.

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