Inductive Sensors Detect Presence of Aluminum Closures on Food Containers

Plastic containers, filled with liquid food products, are hermetically sealed at a food-processing plant. Prior to containers being capped and packed in bulk, in-line testing confirms that each one has been correctly sealed. A long-distance inductive sensor, positioned directly over the packaging line, senses the presence of an aluminum-foil seal over the top of each container.

Aluminum-foil closures are commonly utilized as seals for plastic containers filled with mustard, ketchup and other table sauces. At a food-processing plant, closures are applied to filled containers passing along an automated production line, sealing the contents ready for capping and bulk packaging.

From time to time, equipment malfunctions occur and containers leave the sealing station without closures in place. If unsealed containers are not detected prior to capping, entire batches of product may require manual inspection, resulting in lost production, down-time and potential rejection by customers.

An in-line sensor system must inspect each container and detect the presence of a foil closure, rejecting any faulty items. Each line processes containers in batches; successive batches may comprise filled containers of differing sizes. The system must accommodate containers whose heights vary by up to 20mm, without positional adjustment of sensors between batches.

A single IM30 non flush sensor, located immediately after the sealing station and positioned directly above the production line, provides reliable, repeatable detection of the aluminum-foil closures. With a switching frequency of up to 100Hz, this sensor is well suited for fast-moving production where high-speed sensing is required.