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Transparent-object sensors with patented UV technology detect presence of clear packaging trays on automated packaging lines

Transparent-object sensors with patented UV technology detect presence of clear packaging trays on automated packaging lines

Summary

During automated packaging of medical products in sterile conditions, conveyors deliver clear plastic tray bases to loading stations. Miniature transparent-object sensors with patented UV technology detect the presence of trays as they arrive, enabling the loading cycle to proceed without risk of a line stoppage occurring. Manual intervention is avoided, ensuring contamination-free, reliable operation with little or no downtime.

Application

A manufacturer of packaging machines for the medical industry produces automated blister-packaging lines for pharmaceutical and surgical products. Medical blister-packs comprise a recessed, semi-rigid tray base, vacuum-formed in-line from a clear thermoplastic material and sealed with a metal or plastic film after the desired products are loaded.

Typically, blister-packaging lines for surgical products operate in sterile conditions; minimal manual intervention is permitted, as contamination may enter the environment. If defective bases are identified and rejected after forming, the flow of tray bases to the loading station is not continuous. In this event, a sensor system must inhibit the loading cycle until a base is in position.

Sensors must detect the presence of transparent tray bases swiftly and reliably, enabling the loading cycle to proceed with minimal delay as soon as a tray is present at the loading station. Standard photoelectric sensors, which use visible red-light sources, proved unreliable as they are unable to differentiate reliably between ‘tray present’ and ‘tray not present’ conditions.

An alternative sensor is required which will detect the presence of a transparent plastic target under normal operating conditions.

Solution

Transparent-object sensors with ultraviolet LED-light sources from the Contrinex C23 product series are ideally suited to this application. These miniature cubic devices, mounted above product conveyors, detect the presence of transparent tray bases as they arrive at the loading station. Positioning sensors is simple thanks to a range of adjustable mounting brackets, and auto collimated optics ensure there are no blind zones.

Contrinex transparent-object sensors utilize a patented reflex operating principle with polarized ultraviolet light at 275 nm. At this wavelength, absorption of the polarized UV light by a range of commonly used plastics is maximized. Custom-designed UV reflectors, using high-tech plastic materials with excellent reflective properties in the ultraviolet range, provide a range of sizes and geometries that simplify installation.

An industry-standard PNP normally open output ensures optimum flexibility. Additionally, IO-Link, a standardized point-to-point serial connection protocol for sensors and actuators, is enabled on PNP versions at no additional cost. A second output provides a stability alarm in the event of reduced sensitivity, flagging the need for preventative maintenance before any performance degradation occurs.

Robust sensor construction, featuring miniature (20 mm x 30 mm x 10 mm) Ecolab-certified plastic housings with an M8 connector, ensures reliable operation. A sensing range up to 1200 mm, adjustable via a teach button or via IO-Link, accommodates a range of tray sizes. Sensitivity parameters are stored on the sensor’s inbuilt memory and may be retrieved or updated remotely via IO-Link, eliminating the need for manual adjustment.

These rugged miniature sensors meet the customer’s need for reliable operation with little or no manual intervention. The solution is highly cost-effective with minimal non-productive time. Throughput is maintained at or above target levels.

12th Jan 2019 S.Abedi

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