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April 08, 2016

A large quick-service restaurant chain with its own baked goods operation needed a high-throughput, reliable, safe, and regulation-compliant system to transfer just-baked muffins from metal pans to plastic trays, convey the trays to a freezer, and then to a hand-packing station. To meet the special requirements involved in moving this delicate product, the system integrator for the project turned to BMI to take advantage of our decades-long experience providing leading-edge transfer, conveyor, and pick-and-place solutions to the baked goods industry.

After careful analysis of the requirements, BMI operations manager Todd Frandsen led a team that designed and implemented a conveyor and pick-and-place system which, in addition to fulfilling all the customer’s requirements, has run with zero down time since it first started moving a million muffins a day.

The requirements for the system posed several challenges. The four-ounce muffins emerge from an Autobake Serpentine Baking System oven in 72-cavity metal pans, but in order to meet throughput requirements, the depanning and pick-and-place system had to be designed to empty two pans simultaneously. The plastic trays each have 18 cavities, thus eight plastic trays have to be positioned precisely on a conveyor to accept the total of 144 muffins transferred per pass. BMI integrated a denester that picks plastic trays from a stack and positions eight of them at a time on the conveyor. Finally, the center-to-center spacing of the plastic tray cavities is different than that of the baking pan cavities, requiring the system to adjust on the fly in order to place the muffins properly.

BMI chose to use a FANUC 410-300 robot as the prime pick-and-place mover in the system, as it fulfilled the speed and load requirements of the application. All muffin varieties are delicate and easily damaged or deformed, and this eliminated consideration of some common end-effector types for the FANUC. Suction was ruled out for several reasons, including the likelihood of damaging the product and getting jammed with topping fragments. BMI fitted the FANUC arm with a n SAS needle depanner end-of-arm tool to depan and transfer the muffins. The depanner is equipped with 144 SMC pneumatic actuators, each with a set of needles that when lowered, penetrate the muffins.

Muffins are a vastly popular breakfast and snack item, and the restaurant chain offers several varieties to its customers. The variety of muffins to be moved, all produced in the same facility, presented yet another one of the challenges in designing the pick-and-place and de-panning portion of the system. Different muffin types rise to different heights when baked and topped with different ingredients, and have different textures and consistencies. In addition to a Rockwell Compact Logix Processor to control the system, BMI wrote a simple, user interface program and provided a customized easy-to-use HMI, located outside of the robot safety cage, that allows the operator to adjust depanner motion limits to accommodate changing product heights without having to learn how to use the robot controller itself.

In order to keep the FANUC robot arm moving in perfect synch with the output of the baking oven, an encoder was installed on the discharge belt of the oven to provide line-tracking data to the robot controller.

Although the depanning tool weighs a little over 500 pounds, the weight is well within safety limits for the FANUC. Safety features include regulation-compliant cages around the robot, as well as around the conveyors. Any attempt at opening one of the gates in the safety barriers causes an immediate shutdown of the system.

For this system, as it has for all of its installations, BMI applied its vast experience in conveyors, pick-and-place systems, and the controls that run them. All the conveyors are powered by motors connected to variable-frequency drives (VFDs), which are in turn controlled by the Rockwell PLC programmed by BMI. BMI’s experience with leading-edge technology, and for this project, its long-established, specialized knowledge of the requirements of the baked goods industry, produced a system that met the customer’s requirements perfectly, but far exceeded expectations in terms of flexibility and reliability.

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