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Carrots can be deceiving. Sure, they look healthful and harmless, but that tapering cylindrical shape is much harder to handle than a nice round apple or tomato, especially if you’re a production-line machine. Just ask Mike Opperman, instrument and controls designer at Bolthouse Farms in Bakersfield, Calif., which together with its main competitor produces and processes about 80% of the carrots and related products in the U.S.
In 10 years at Bolthouse, Opperman has helped build 60 to 80 machines that sort, process, and package carrots into an increasingly diverse range of products, especially beverages. Because carrots need special handling, Bolthouse designs and builds many of its own machines, and then organizes them into long production lines. Sensors and I/O devices help these machines sort, peel, wash, trim, cut and weigh the carrots, and then roll out plastic packaging, detect ends and weigh packages. Recently, Bolthouse opened two bottling plants and one salad dressing plant, and these needed production lines and machines, too.
Traditionally, Bolthouse’s machines used hardwired I/O components, and had to run more than 300 points back from hundreds of instruments in massive cable trays to motor control centers and PLC combinations. “As we expanded into more complex processes, beyond motor starts and stops, we had analog and digital signals too, and so we kept expanding the racks as we added more hardware from the field,” says Opperman. “Now, we had 500 to 600 instruments installed, and each had individual wires and connectors. However, even though we were very careful about precisely labeling each, so we wouldn’t need a schematic in the field, we still needed two people to do troubleshooting.”
Opperman says Bolthouse began seeking to revise the increasingly unworkable wiring situation on its machines and network about five years ago. “We starting looking at the labor and material costs, and found that on a typical, smaller, $15,000 machine, we could save $5,000 by doing on-machine wiring with DeviceNet, AS-i, Profibus or a similar protocol. Basically, all the machine’s instruments would just go back to a Turck block on the machine, and then only four wires would go off the machine and back to the PLC. This meant we could save multiple hundreds of thousands of dollars over the course of building a larger project such as one of the bottling plants.” These four wires, two for communications and two for power, are usually run in a single cable. This network typically runs at 125 kbps, which gives Bolthouse all the data throughput and reliability it needs.
Tale of Two Bottling Plants
This shift in its networking strategy also occurred between the time Bolthouse built its first juice bottling plant about seven years ago, and when it built its second plant about three years ago. The two plants bottle the same juice products in all container sizes between 350 ml and 2 liters. The first plant consists of a French design, using hardware from Schneider Electric’s Telemecanique division, to run 9,000 bottles per hour. The second is a German design with hardware from B&R and Rockwell Automation that run 15,000 bottles per hour.
“Both plants use distributed I/O systems and there isn’t much difference in the machine-mount I/O at each, but the newer plant’s system is just more compact. The first plant and its machine can do different sizes, but the second one is able to do it easier. For example, the newer machines’ design and software make it easier to do lane changes to shift product,” adds Opperman. “Likewise, using DeviceNet and the other fieldbuses reduces the footprint and impact of our machines, and makes them easier to build. Running wires used to mean we had to get into the tray, and shut down the process. Now, we just run a couple of commissioning cables, and we almost can do it during a regular production break. Also, when we buy from an OEM, we now ask them to integrate their machines with our network. If they’re not prepared to offer a fieldbus, we buy the machine, and custom add it ourselves.”
In addition, Bolthouse recently updated its 12-year-old, three-stage evaporation system that makes concentrated juice. It originally had three rudimentary, closed control loops. However, this was a very operator-intensive process that involved manually adjusting the machine and inputting set-points, which allowed too much latitude and potential for product variance and errors.
“Now, we’re using machine-mount I/O to go with a recipe-based system in the evaporator that’s already in some other Bolthouse machines,” says Opperman. “To follow a recipe, it uses preset algorithms to make changes such as adjusting flow, temperature and pressure. We also have heat exchangers between each stage, and they need flexibility to handle variations between the different vegetables. All the control valves and controls need a wide operating range to manage these differing viscosities. All of these needs are helped by our machine-mount I/O cabling and components.”