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Robot makes burrito packing grande

Born out of the idea that busy vegetarians need convenient meals too, Amy's Kitchen was founded in 1987 to produce healthy, organic frozen foods. At the time, the brand created a new product category, but sales of natural foods have seen the market mushroom to $15 billion annually, and Amy's continues to expand at a rate of approximately 20 percent to 25 percent per year. Amy's Kitchen now offers about 100 products and produces up to 5 million meals each month, ranging from pizza to soup, and from burritos to whole meals. To cope with the continual growth, the company recently invested in the latest automated wrapping and handling equipment from Doboy, a Bosch Packaging Technology co. (www.doboy.com), including a unique robot application for its packaging of burritos and pockets.

Amy's Kitchen looked to local Doboy sales partner, Scott Patrick, owner of Bay Area Packaging (www.baypack.com), to find an affordable and efficient product handling and packaging solution. "After reviewing the current operation and application needs, and understanding their growth strategy, it didn't take long to realize that automation from Doboy equipment would be the best investment," says Patrick. Bert Pires, engineering manager at Amy's Kitchen, echoes those sentiments. "We've had great experience with Doboy and Bay Area Packaging in the past, so they were an easy choice for the burrito and pizza projects," he says. "The ability to pack both burritos and pockets was critical, and the robot is doing an excellent job."

Burritos, pockets and pizzas are frozen in a spiral freezer, and the frozen products are delivered to the burrito/pocket line and to the adjacent pizza line on a descending conveyor. (See the accompanying sidebar.) The conveyor can only deliver products to one line at a time, and during PD's visit, it was delivering pizzas.

"We were the first site using the Presto Robot in the way we do, with two product lines being served by the single machine." - Plant Engineer Dave Caravetto

Frozen burritos, which were being run on the burrito/pocket line, were brought to the line in large cartons and were manually placed on a rotating table that discharges them single-file onto a conveyor feeding a Doboy Linium 301 flowrapper. An in-line feeder spaces the burritos as they enter the wrapper, which pulls film from a roll mounted overhead, forms it around the burrito and creates a longitudinal fin seal to form a continuous tube around the burritos as they travel through the machine. The packages then travel through a set of rollers containing heating bars that seal and cut the film to produce individual packages. A Markem (www.Markem.com) ink-jet printer applies a code date to the film as it enters the wrapper.

A pick-and-place robot at GU Sports uses the latest Doboy Delta parallel-axis technology to handle up to 400 gel packs/min. See www.packagingdigest.com/info/GU

The PLC-controlled wrapper is equipped with a graphic control panel and a servo-driven infeed, finwheels, side channels and cutting head. The operator can program the package length, operating speed and dwell time for each product, and this data will be retained in memory. When changing to a different product, the operator simply enters the product name, and the machine is changed to the new operating settings automatically.

The packages leaving the wrapper make a 90-deg turn and pass through a Thermo Electron (www.thermo.com/food) DSP3 metal detector. This unit, which has an easy-to-use menu with automatic product calibration, incorporates digital signal processing (DSP) technology and AuditCheck™, a unique and patented device that validates the performance of the metal detector.

Quick changeover from burritos

From the metal detector, packages continue to the robot. Offering much more flexibility than conventional robots, the mobile structure of a Delta Robot resembles an upside-down tripod. The segments are not in succession as is typical with conventional robots. Instead, the segments form three closed loops, called joint-plan polygons. This kind of robotics is called parallel axis robotics where all joints of a loop are dependent on each other, and therefore each joint has the ability to change the position of the entire polygon structure. With this kind of polygon structure, an actuator is not required at every joint, and in addition, the actuators can be located in fixed positions and do not have to move with the structure. This results in the removal of all large masses from the moving structure, and the Delta Robot arms are able to move at exceptional accelerations-up to 10 times the speed of gravity. This unique concept saves both space and money. Lightweight and compact, the unit has few replacement parts and houses its motor in its stationary base structure, giving the robot a sleek, streamlined appearance.

"The installation at Amy's Kitchen posed a number of challenges, including optimizing the robot's capacity and also making use of every square inch of floor space." - Scott Patrick, Bay Area Packaging

Wrapped products are delivered to the actuator section of the robot packer, which places them into cavities on a conveyor running at a right angle parallel to the pick-and-place section. The robot performs different functions for burritos and pockets by converting back and forth between a top loader for burritos and a feed placer for pockets. This is what makes this robotic application so unique.

When packing burritos, the robot top-loads the products into a cardboard tray, typically four across and three deep. It provides 98 percent efficiency while packing 160 burritos/min. The robot picks up four burritos at a time with vacuum cups, swings over the tray and deposits the products.

Trays for the burritos are formed from blanks by a Doboy tray former. A Nordson (www.nordson.com) Model EPC 30 Eclipse Series glue system applies hot-melt glue to tray blanks, which are then folded into shape.

The changeover of the robot to handle pockets, which is a distinctly different task, takes just minutes. As with the flowrapper, the PLC-controlled packer can be programmed for different products with the data retained in memory. The operator only needs to enter the product name to change its operation. The only mechanical change required to convert the machine from a burrito top-loader to a pocket feed-placer is to move a clever hinged conveyor assembly out of the way. This simple solution allows the robot to handle 130 pockets/min, picking up the wrapped pockets and accurately placing them into a moving chain for the end-load cartoner. The parallel-axis robot maintains high speed and accuracy, while the specially tailored grippers are able to pick the irregular shapes of these hand-made products reliably, time and time again. The line is equipped with a separate carton former for the pockets.

Immense satisfaction with its burrito and pocket packaging equipment led Amy's Kitchen to turn to Doboy for its pizza wrapping as well. Amy's recently installed a Doboy Linium 305 horizontal shrink wrapper integrated with a Servo SmartFeed™ infeed conveyor that Shuttleworth Inc. (www.shuttleworth.com) developed specifically for frozen pizza applications. The unit accepts random input of the pizzas and sequences them with proper spacing between the flight-chain fingers to feed the wrapper. The conveyor is designed to absorb irregularities in the production flow to provide a smooth, even flow on the line.

According to the National Frozen Pizza Institute, 2003 supermarket sales of frozen pizzas in the U.S. were $3.3 billion, and with an average sales growth increase of 6 percent a year, frozen pizza represents one of the fastest-growing segments of the entire frozen food category. Unfortunately, the implementation of automated systems needed to facilitate the increased demand has not kept pace with the growth in orders. This is showing up mostly downstream in the assembly cycle with wrapping and the infeed system that supplies it.

"Just about all pizza manufacturers have problems with throughput on production," says Dave Larson, technical support with Doboy, Inc. "When downstream equipment is running inefficiently and not keeping up with the assembly flow, it does not leave the pizzas any place to go. This results in an accelerated pizza traffic jam, slowing of the process line, or the stopping of it altogether, and an inevitable increase in damaged pizzas." Doboy's wrapping machines, which are commonly used for pizza wrapping, are capable of handling up to 170 or more 12-in.-dia pizzas/min and as many as 250 fun-size pizzas/min. This would certainly be considered high-speed production, but, in fact, it exceeds the infeed capability of manufacturers, both hand-fed and automated. So, even if a manufacturer has a high-speed wrapper, its production is limited by the rate of infeed.

pizza "Pizzas are a difficult product to wrap," says Todd Eckert, packaging program manager at Shuttleworth. "They have a lot of loose ingredients on them that tend to shift around and fall off, and their extended shape requires very careful handling to keep from damaging them." When running at high speeds, most infeed systems cannot maintain proper indexing with the wrapper, Eckert says.

Shuttleworth's conveyor infeed solves this problem. Their Servo SmartFeed conveyor accepts random input of frozen pizzas and sequences them, with proper spacing, between the flight-chain fingers to feed the wrapper. Low line pressure throughout the system's continuous-motion accumulation area allows for proper product placement. Should the wrapper need to stop or slow, the conveyor can continue to take production from the line for a period of time instead of stopping. A low-pressure accumulation buffer absorbs irregularities in the production flow and provides a smooth, even flow on the line. "The Servo SmartFeed operates in four speed-registration zones to manage the pizzas optimally," Eckert says. The first zone accepts the pizzas from the freezer, then conveys them at two to three times the case speed; the second zone closes the gaps between the pizzas so they run back-to-back; the third zone increases the spacing between the pizzas equal to the pitch flight on the wrapper; and the fourth zone positions each individual pizza into the gaps between the flights. The Servo SmartFeed is synchronized with the wrapping machine due to encoder feedback from the wrapper. A sensor identifies each product location, and the conveyor accelerates or decelerates the product to place it into position on the flighted infeed of the wrapper. The length of the Shuttleworth Servo SmartFeed is determined by product rates, sizes and process flow consistency.

A key component of Shuttleworth's Servo SmartFeed system is its Slip-Torque technology for creating low backpressure. This utilizes the coefficient of friction between the individually powered rotating roller shafts and the loose-fit rollers to control the driving force of the product. The size and weight of the product determine the driving force and roller selection. When product stops on the conveyor, the segmented rollers beneath the product also stop, generating low backpressure accumulation so product damage is minimized.

Wrapping machine technology plays an important role in packaging line efficiency. With automated feeding, the ability of the wrapper to integrate with upstream automation and respond consistently to speed commands is critical. Doboy's Linium wrappers incorporate servo-motor technology that provides the responsive control needed for efficient automation. The controls and software solutions are able to optimize equipment speeds, accelerations and decelerations to match process requirements and respond to automated infeed commands.

Doboy and Shuttleworth have integrated their wrapper and feeder equipment for pizza packaging. "The Shuttleworth feeding concept was one we felt would work well for automating Amy's Kitchens' pizza line," says Steve Lipps, product line manager for horizontal wrapping at Doboy. Says Ekert, "Amy's Kitchen produces a lot of pizzas. They have a very high-volume operation and wanted to double their wrapping capacity. We were looking to resolve difficulties that they were experiencing with their original feeding equipment. As with most every other system in the frozen pizza industry, throughput was limited by rate of flow from the feeder, and was literally limiting their production flow by 50 percent. The integration of Shuttleworth's Servo SmartFeed and Doboy's Linium wrapper solved the difficulties."

The smart infeed conveyor, far left, accepts random input of frozen pizzas and sequences them, with proper spacing, between the flight-chain fingers to feed the flowrapper. The infeed system is synchronized with the wrapping machine due to encoder feedback from the wrapper. Cartons pass through a metal detector, left, before they are manually packed into cases.

Plant engineer Dave Caravetto highlighted that the robot has been reliable and productive. "We are currently acting as a beta test site for Doboy by putting a new fail-safe gripper through its paces," he explains. "We were the first site making use of the Presto..."

More information is available:

  • Robotic pick-and-place unit, flowrapper, tray former:Doboy, a Bosch Packaging Technology co., 715/246-6511. www.doboy.com. Circle No. 208.

  • Robot, flowrapper, tray former representative:Bay Area Packaging, 888/933-8700. www.baypack.com. Circle No. 209.

  • Ink-jet printer:Markem Corp., 603/357-4255. www.Markem.com. Circle No. 210.

  • Metal detector: Thermo Electron Corp., 763/783-2500. www.thermo.com/food. Circle No. 211.

  • Glue system:Nordson Corp., 770/497-3700. www.nordson.com.Circle No. 212.

  • Ink-jet printer:Videojet Technologies, Inc., 630/860-7300. www.Videojet.com. Circle No. 213.

  • Shrink wrapper:Extreme Packaging Machinery, Inc., 949/888-7221. www.extremepkg.com. Circle No. 214.

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