Since opening in 1963, the Unilever Canada Lipton dry soup and side-dish production and packaging plant in Brampton, Ont., has undergone several expansions. As a highly efficient producer, this location was the choice for the North American production base for over 150 different Lipton and Knorr soups and side dishes. The plant encompasses the entire process, from raw materials and mixing to packaging and shipping. Unilever produces more than 30 million cases of packaged products annually at this plant.

Today, the company continues to upgrade its practices and facilities to achieve its sustainability goals, including a plan to increase machine operator safety while achieving faster production through reduced downtime.

An inefficient beginning
One of the pieces of equipment Unilever upgraded was its Bartelt-brand form, fill and seal machine, which produces its Knorr Asian SideKicks. Rollers feed the pre-printed airtight foil into the automated machine, where the foil is folded, sealed on three sides, cut into separate pouches, opened, filled, then laser-labeled and sealed before it exits the machine onto a conveyor. This entire process is done within an enclosed Plexiglas environment to keep the product sanitary and still provide visibility into the operations. Plexiglas access doors at each station used magnetic safety switches with relays that signaled the entire line to stop when a door is opened. This was designed to protect employees from moving machine parts.

With the magnetic safety switch system, the operator panel displayed “Guard Door Open”; however, it did not tell the operator which door it was referring to. Various machines have between 15 and 20 doors, so machine operators found it time consuming to figure out which door was open and, therefore, which station had the problem.

The existing hard-contact, safety-interlocking door switches kept the employees and machines safe, but if an issue occurred with the switches, it caused downtime, difficulty troubleshooting and lost production. The existing magnetic switch system could also be overridden, potentially creating unsafe conditions.

“It took time to contact an electrician, him to get there and find the problem, then maybe he has to go get parts — it can turn into half an hour or an hour,” says Jose Suarez, plant engineer at Unilever Canada.

To meet demand, the company produces about 100 pouches per minute. He estimates the value of downtime is about $7 per minute — so every second counts. Downtime doesn’t stop Unilever from filling its orders though. They must make up the lost production with a second shift and overtime pay that increases operations costs and decreases profits.
Unilever needed a solution that could indicate which of the many doors was open and which switch is faulty that would not allow override and would reduce the amount of safety relays.

“We wanted better efficiency, improved safety and complete reliability,” Suarez said.

Choosing RFID switches
Frustration with downtime inspired an innovative Unilever employee to suggest upgrading the safety switches. Unilever worked with Concord, Ont.-based Gerrie Electric, a Rockwell Automation authorized distributor, and its sensor and safety specialist, Gadi Hamou.

The food producer began a sample of Rockwell’s SensaGuard RFID non-contact safety switch on one machine. The switch uses inductive technology for sensing, and the RFID (radio frequency identification) technology uses a code that looks for the matching RFID partner block before the machine is allowed to start.

The machine cannot be operated if a monitored door is open, and it is undefeatable to steel or magnetics so it cannot be held open and overridden while it is still running.The product is designed and built to global standards rated Category 4/SIL 3 per EN954-1, and TUV functional safety approved to IEC61508. LED indicators located on the switch give a visual indication of door status; indicate door misalignment and offer advanced diagnostics to help identify faults.

“The SensaGuard was the perfect solution for Unilever’s application,” Hamou stated. “The ability to provide indication lights and reduce the amount of safety relays made this conversion possible.”

This solution provided the ability to connect 15 switches to one safety relay to communicate to the main panel. The light indication on the switches provides the information to diagnose a problem. “Green indicates everything is good,

flashing red indicates that a switch in the switch string is open, and red indicates that a particular switch is open or the switch is faulty,” Hamou explained.

Results
Unilever Canada installed about 170 SensaGuard non-contact safety switches on doors on various operations throughout the plant. The solution had standard and safety products working together to turn the safety capital outlay into an investment with positive returns.

The indicator lights on the switches help minimize downtime and makes troubleshooting easier by pinpointing the faulted sensor and identifying it to the operator. It helps operators safely access areas of the machine where there is motion and gives them more control to keep the line running as much as possible.

“The operators on the new machines love these sensors,” Suarez said. “They can identify the problem without calling an electrician. It actually helps improve morale, as the operators can resolve the problems themselves and have a greater sense of control.”

Unilever Canada’s solution met the criteria it was aiming for: to indicate which door is open, which switch is faulted, and be able to fix issues without the assistance of an electrician, while also reducing the amount of safety relays needed on each application. The combined experience of Gerrie Electric and Rockwell Automation in machine safety and industrial automation helped them to understand its factory-floor issues and the solutions.

These switch upgrades have helped Unilever increase efficiencies by three percent over the past 14 months. Unilever has many more sustainability projects in the pre-engineering phase and plans to upgrade its remaining machines with the same SensaGuard switches over time.

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This is an edited article provided by Rockwell Automation. For more information, visit ca.rockwellautomation.com.