Photoelectric sensors take high temperatures, chemical sprays in Elopak filling machines

Elopak, maker of carton-based packaging systems for non-carbonated liquid food and non-food products, needed more rugged discrete sensors and worked with ifm efector's OG Series photoelectric sensors for washdown conditions.

October 7, 2009

Unformed gable-top cartons are placed in feeder trays at the front of the Elopak Pure-Pak aseptic filling machine. A series of ifm OG photoelectric sensors detect the sides of the cartons for proper flow-through.

Packaging machines endure high pressure chemical sprays and temperatures from 20 °C to 100 °C, which can eat through traditional sensors like a kid in a candy store. Elopak, a New Hudson, MI, maker of carton-based packaging systems for non-carbonated liquid food and non-food products, endured problems associated with discrete sensors that were not rugged enough for its aseptic filling machines.

Seeking fewer sensor failures and better support, Michael Ballinger, Elopak manager of electrical engineering, and his team searched for a position sensor that better matched application requirements, including ability to withstand high temperatures.

A rotating mandrel grips formed cartons from the feeder lines and places the cartons on a chain conveyor sending them to the Elopak Pure-Pak filling station. ifm OG photoelectric sensors detect proper carton height on the conveyor to ensure proper filling levels.

The Elopak filling machine is central to the carton production process, completing most logistics for carton production. The filling machine forms, fills, and seals a carton before being safely packed into one of Elopak’s material handling systems. A typical filling machine, the size of an overseas shipping container, can process up to 12,000 cartons per hour.
Aseptic filling machines create the toughest sensing environment.

Elopak’s model E-PL90HA filling machine enables customers to produce and fill cartons with acidic products that have a one-year shelf life. Cleaning cycles, which run every eight hours and last three hours, expose the machine and its control devices to temperature fluctuations from 20 °C to 100 °C, high-pressure sprays, and chemical sprays of Oxonia Active. During carton production, the machine and control devices are exposed to temperatures between 70 °C to 90 °C, and are subjected to a sterility chemical spray of 35% peroxide (H2O2).

While other machine parts were withstanding such exposure, position control sensors were failing under the intense cleaning. Water and chemical sprays caused condensation to build up inside the sensors, causing short circuits.

ifm’s OG washdown photoelectric thru-beam pairs, on either side of a chain conveyor, detect the leading edge and trailing edge of cartons (below) as they travel through the Elopak Pure-Pak aseptic filling machine. The sensor’s visible red light source assists in alignment and can burn through water droplets on the sensor face.

In addition, water seeped inside cable connection seals and corroded the connection pins, causing failure. Large water droplets also formed on the sensor face, creating false signals or no signals.

Elopak found a solution in Elopak, maker of carton-based packaging systems for non-carbonated liquid food and non-food products, needed more rugged sensors and worked with ifm efector’s OG Series photoelectric sensors for washdown conditions. These have stainless steel construction, high temperature compatibility, and Ecolab certification.

The 18 mm diameter sensors have an IP69K international protection rating, which ensures the sensor housing is dust-tight and can withstand high-pressure, high-temperature washdowns.

Multiple ifm fiber optic cables are placed above passing cartons to verify that the top of the carton is completely formed. The cables feature stainless steel sheaths to withstand high temperatures and wet environments in the Elopak Pure-Pak aseptic filling machine.

Ballinger says a high-intensity visible-red light source burns through water droplets on the sensor face, providing a reliable signal and assisting with installation alignment.
Sensor specifications and rugged construction also avoid "false signals or no signals that would result in bad cartons being produced," says Ballinger.
Labor is saved because machines no longer require frequent sensor replacements. Machine efficiency has increased with installation of the OG sensors, and productivity also has increased, says Ballinger. He is also pleased with service and technical support, and expects more cost savings in the long run.


How the filling machine works

After the Elopak Pure-Pak filling station, formed and filled cartons travel on the conveyor to the sealing station.

The process begins with the filling machine accepting a cardboard sheet, which can include two or more layers of various materials such as polyethylene, paperboard, aluminum and OVOH-barriers, depending on the type of liquid being filled.

The machine forms the sheet into a specified carton size and fills the carton with a liquid food product, such as milk, juice, or smoothies.

Finally, the carton is sealed and a closure cap is applied.

Elopak Pure-Pak curve cartons can be printed on the curved edge for more impact on busy story shelves.

Because of the variety of beverages that run through a typical filling process, the machine is subjected to harsh washdown conditions to maintain sanitary conditions.

Food and beverage sterilization requires intense cleaning cycles.

Read more about sensors at the Control Engineering industrial sensor channel .

– Edited by Mark T. Hoske, editor in chief, Control Engineering ,