Control at critical control points
An automated rejection system with multiple pack sensing and control devices ensures that contaminated packs are properly removed from the line. The automatic reject mechanism is controlled via input from the metal detector and the pack sensors, enabling the contaminated product to be removed without stopping the production process. If the correct pack has not been removed, a reject confirmation sensor triggers an alarm.
A secondary reject check sensor further along the conveyor belt signals a fault should the rejection mechanism fail or the pack in-feed sensor malfunction. If there is any failure, then an alarm is activated, stopping the machine. All activity is monitored and documented within the detector.
It is widely believed procedural failure, such as the inadvertent replacing of rejected products on the production line after inspection, is a principal cause of metal contamination, rather than metal detector failure. Providing a tunnel guard on the out-feed conveyor prevents external interference with inspected packs and ensures that only uncontaminated products are advanced for final packaging and distribution, lowering the risk of expensive product recalls.
As a further safeguard, the due diligence enhancement features a lockable reject bin to prevent the placement of rejected packs back on to the conveyor. Access to the reject bin is gained through the touch-screen interface of the metal detector, which includes a high-security password protected operator access and event logging system. This system records all operator access and unauthorised login attempts, ensuring only authorised personnel can access the detector controls and reject bin.
Contact: Mettler Toledo
