Contrinex inductive and fork sensors ‘keep the lid on’ ketchup bottles

Some of the most compelling examples of automation are in food packaging, where the extensive use of high-speed automation means that equipment performance and reliability are valued because line stoppages are both costly and time-consuming.

Contrinex Photoelectric Fork and Inductive sensors are trusted to ‘keep the lid on’ and to help get a bottle of ketchup to the customer’s table by ensuring that the ketchup is hermetically sealed and that the flip-top cap has been fitted.

Plastic bottles that have been filled with ketchup pass under a Contrinex inductive sensor positioned over the packaging line which confirms the presence of an aluminium-foil seal. Next, the fitment of a plastic flip-top cap is verified by a Contrinex Photoelectric fork sensor before the bottle is released for labelling, packaging and despatch to customers.

Contrinex has the largest selection of sensors with the IO-Link communication protocol in the world and for example, the fork-sensor is switched between four operating modes according to the production batch using IO-Link. Being a communication protocol, IO-Link feeds back to the production line control system, information from the inductive and fork sensors such as their preventative maintenance status. A brief overview of Contrinex’s IO-Link offering can be found at

Customer application

To ensure product freshness and safety, a hermetic seal must be fitted below the cap of packaged products like ketchup. Previously, if the seal or plastic cap was missing it could go undetected, risking an entire batch of production potentially being rejected.

Customer solution

Plastic bottles that have been filled with ketchup pass under a Contrinex 500 Series ‘long-distance’ inductive sensor positioned over the packaging line which confirms the presence of an aluminium-foil hermetic seal on the top of every container. The highly sensitive Contrinex inductive sensor was selected because of its ability to reliably detect at speed the very small amount of aluminium present in the seal.

Next, the bottle passes through one of Contrinex’s highly versatile and high-performance photoelectric fork sensors, which senses the presence of a cap on the bottle before its release for labelling, triggering an alarm if a cap is missing.

Contrinex’s LG fork light-barrier photoelectric sensors were chosen because they combined the simplicity of installation, with a choice of four modes of operation. The compact sensors provide high-resolution and high-speed sensing, plus the convenience of a push-pull output and IO-Link connectivity. Ideal for detection of the lids, these robust die-cast metal sensors provide high-performance and reliability.

Multi-mode operation flexibility

Four preconfigured operating modes enable the fork sensors to fulfil a wide spectrum of application needs – ‘Standard mode‘ provides switching frequencies up to 5,000Hz with a resolution of 0.3mm, while ‘High-resolution mode’ ensures precise detection of small objects down to 0.1mm in size.

Where the production batch requires it, switching to ‘Power mode’ increases the transmission power of the sensor, reducing its sensitivity to dirt or other contamination. For high-speed applications, ‘Speed mode’ raises the switching frequency as high as 14,000Hz, ensuring reliable sensing of fast-moving targets.

Application-specific configuration

The IO-Link communication protocol enables remote set-up and adjustment of the fork-sensor between production batches.

IO-Link stores the sensor’s configuration on a local IO-Link Master, which enables plug-and-play operation, eliminating the need to stock multiple pre-configured sensors in spare part inventory. The compact design and placement of the photoelectric emitter and receiver in a single housing saves space, ensures precise alignment and removes the need for on-site adjustment.

Robust and highly versatile, these metal-cased devices offer fast and easy installation is provided by the choice of clearance mounting holes for M4 fixings and an integrated M8 connector.

Contrinex sensors and more information are available from PLUS Automation.

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