Profiting from Speed and Control

Mullins Food Products, Broadview, Ill., a contract blender and packager of condiments for the fast food industry, is using servo-drive technology linked with personal computer (PC)-based line control to increase production speed and decrease waste.

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In search of greater output, Mullins picked a high-speed, three-axis casepacker from Soleri Design/Automation Inc., of West Lake Village, Calif., equipped with a servo system from the Bosch Rexroth Corp., Hoffman Estates, Ill. Designed to accelerate speed across the entire production line, Soleri’s casepacker and corresponding Rexroth components are integrated with an upstream, previously installed cup-filling machine from Winpak, San Bernardino, Calif.

When the filled one-ounce cups travel down the production line toward the packaging area, 50 containers are picked up by the casepacker’s suction head and then oriented and placed in the case. While a current set of cups are being placed in the box, a separate pick head places a cardboard slip sheet between each layer of cups to add strength and to ensure the cups are not damaged during shipment. There are five layers, providing a total of 250 cups per case.

The casepacker is driven by Rexroth Indradrive digital servo drives and MSK servo motors. The drives offer distributed intelligence to close all the loops down in the drive, freeing up the controller to calculate and execute the pick-and-place path planning. A key component of the system is its Rexroth PPC-R controller, a Power PC-based motion and logic controller that resides upstream on the Winpak cup-making machine.

Extending control

The PPC is available as a PCI plug-in card for integration into a PC, or, as at Mullins, as a rack-mounted controller. The controller synchronizes all servo motions, and controls both the Winpak cup machine and the Soleri casepacker. As a result, the speed of each machine directly corresponds with the speed of the other one. For example, if the Winpak machine ramps up its production to 65 cycles per minute, the casepacker can seamlessly adapt to handle the volume, allowing an overall increase in line speed.

“In terms of calculating production, we are ultimately measured by cycles per minute, and with this casepacker, our throughput times have accelerated nicely,” says Larry Coons, maintenance manager at Mullins. “Prior to the installation of the Soleri machine, we maxed out at around 58 to 60 cycles per minute. We’re now running at least 70 cycles per minute—about 17 percent faster production.”

Production volume isn’t the only thing that’s improved. Coons said package and product waste have also decreased. With the servo system, the machine is designed to move slightly slower while the cups are en route to the box, but faster on the return to pick up more cups. This overall controlled action reduces the potential for lost or damaged products, a number which Coons said has dropped by nearly 10 percent.

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