Potent brew

Mixing an Allen-Bradley ControlLogix controller with DeviceNet communications helps Lipton reduce downtime and engineering costs

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Known to botanists as camellia sinensis, the tea plant bears no resemblance to the leaves you steep in boiling water and serve with crumpets, jam and sympathy. Five to six feet tall, the tea plant is an evergreen with small, apple blossom-esque buds. To turn this shrub into a steaming cup of Earl Grey is a complex process that involves harvesting, withering, rolling, fermenting and drying the plant's leaves. And that's just the beginning.

 

Most commercial teas are a blend of leaves from various plants, and also include other dried herbs, fruits, etc. Mixing complementary flavors allows companies to create teas that are aromatic and delicious. This is where Lipton has made its mark. Owned by Unilever, Lipton produces the world's most popular and widely sipped teas. Its products can be found on store shelves in more than 100 countries.

 

To keep up with customer demand, Lipton recently upgraded a conveyor chassis at its manufacturing facility in Suffolk, Va. Featuring equipment from Rockwell Automation and its encompass partner SMC Corp., the new conveyor system cost significantly less than a traditional, hardwired installation, and it took less time to bring online. Most importantly, it's a vast improvement over the tangle of wires and conduit that was previously in place.

 

"Since start-up, there have been no snags," says Keith Rock, lead engineer at the Lipton plant in Suffolk. "The new system has been so effective we're using it as a blueprint for upgrading three similar applications."

 

In the bag

Saying that you drink tea is as nebulous as saying you live on Earth. That's because there are several varieties of tea -- black, green, herbal and instant -- and thousands of options within each category. This is the reason behind Lipton's vast catalog, which ranges from blackberry-infused leaves to lemon ginseng green tea. And it helps give Lipton a global turnover of almost $2 billion.

 

The Suffolk facility primarily packages black teas. And since tea bags don't grow on trees, Lipton has a multi-step process in place to make sure its customers' cups are always full. To start, trucks arrive at the Lipton facility to deliver dried and shredded leaves from tea plantations around the world. The leaves are then blended, depending on the production run and specific recipe. Next, the tea blend is transferred to the plant's packaging machines that produce double chamber tea bags.

 

Feed the machines

Although the process begins and ends on the bed of a truck, there are many activities in- between that Lipton employees must coordinate so the tea can make the trek from one end of the facility to the other. Problems in any area can make the entire operation resemble a Los Angeles freeway during rush hour. Unfortunately, due to a matrix of canvas-belt conveyors, this was becoming an all-too-common occurrence.

 

These conveyors (a conveyor chassis collectively) transport empty boxes to the machines and transport full boxes from the machines for further processing.  This can include a complex assortment of carton sizes.

 

 "That's why it's a matrix of conveyors rather than one belt spitting boxes onto 40 machines," Rock says. "We have to make sure no machine is starving."

 

The challenge is to get the right box to the right packaging machine at the right time. Otherwise, the packaging machines sit idle, throughput lags and orders are delayed.

 

Break it down

Along with the conveyor track, the old system was comprised of metal diverters that pushed empty boxes to the appropriate machines and brake paddles that controlled the flow of boxes. Lipton also placed photo eyes before each diverter or brake. These eyes would sense cartons traveling through the chassis and manage the flow of cartons to individual machines.

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