Contrinex photoelectrics are ‘sweet’ for conveyors

Photoelectric sensors are essential elements of the automated packaging systems used on food packaging lines to deliver the high efficiency and reliability required.

The production of confectionery is an example of very high-volume production, and one customer packs sealed bags of confectionery in cardboard cartons, which are in turn shrink-wrapped, stacked and palletised.

A ‘sweet’ and reliable operation is ensured by Contrinex’s small, but high-performance through-beam C23PA photoelectric sensors, which are mounted beside the conveyor outfeed from the carton heat-shrink oven.

These low-cost sensors not only offer high-performance but also a choice of mounting brackets and protection shields to speed up installation. There is also the option of an additional switched output which provides a stability alarm. The alarm signals the need for maintenance, for example, reduced sensitivity due to dirt on the lens, flagging the need for preventative maintenance well in advance of any decline in system performance.

Cardboard cartons filled with bags of confectionary pass through a heat shrink station for wrapping before being conveyed to a consolidation area for stacking and palletisation. The wrapping machine encloses each cardboard carton inside a tube of heavy-duty heat-shrink film; the carton then passes through an infrared oven, where the film shrinks, forming a sealed and robust box.

The production system needs to monitor throughput for each of several packaging lines and automation removes the cost and the unreliability of manual counting. A highly reliable sensor system is therefore needed to detect the presence of each pack as it leaves the shrink-wrapping area and to update the count held on the factory’s control system. High-performance sensing is required to ensure reliable operation irrespective of carton size or location on the belt and to ensure there are no issues from the reflectiveness of the shrink-wrap.

The small and low-cost through-beam photoelectric sensors from Contrinex’s C23PA range offer a solution for this application. Despite being only 30 x 20 x 10mm in size, these sensors have a maximum sensing range of 30 m. The sensors are mounted with the transmitter and receiver on opposite sides of the conveyor, immediately after each oven.

Depending on access to the area at the oven outfeed, the long sensing range of the sensors, enables them to be located some distance away from the conveyor. The sensor’s integral alignment aid ensures a rapid and accurate set-up, even at extremes of operating range

As each carton breaks the light beam, the sensor detects its presence and signals the control system to increment the item count. Available with a choice of industry-standard PNP or NPN, 3-wire or 4-wire outputs, the sensors also provide an optional stability alarm in the event of reduced sensitivity, flagging the need for preventative maintenance before any performance degradation occurs

In other applications, the C23PA photoelectrics can detect fast-moving targets reliably and offer a remote selection of switching frequency via IO-Link. A sensing range up to 30 m, is adjustable via a teach button or via IO-Link, accommodating a wide range of machine geometries. 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.

Mounting the sensors is made simpler and lower cost, by Contrinex’s selection of custom-designed, multi-position metal mounting brackets and protective sleeves.