Filling a sandwich is not particularly difficult, unless it is being done on an industrial scale with a throughput of thousands of sandwiches per hour. One American business is making a determined effort to further automate the process. Founded in 1972, the family-run Grote Company of Columbus, Ohio, has established a global reputation as a specialist in the mechanization of sandwich making. Until recently, the upper and lower halves of the sandwich were put together manually. Now Grote has managed to automate this process as well, using a Stäubli TX2-60 HE six-axis robot with wash-down capability.

At the heart of the assembly line is a six-axis robot, the Stäubli TX2-60 HE. After assembling the sandwich halves, the robot rotates the sandwich 45 degrees and positions it diagonally on the conveyor belt. It then proceeds to the last station, where the sandwich is cut in half or quarters in the desired configuration. Now the snack is ready for packaging. Up to 60 sandwiches per minute per lane can be produced in this way, with twin lines available to double production up to 120 sandwiches per minute.

The robot gripper is guided to its target using 3D image processing. Developed in house, the gripper enables reliable handling of the sandwich’s top slice, which is pliable in nature and thus difficult to grasp firmly.

The entire production line complies with the principles of hygienic design. All edges are rounded, so there are no dead spaces where debris can build up, and the sandwich production line can withstand even the harshest cleaning procedures. To ensure maximum availability, Grote opted for a Stäubli HE (Humid Environment) robot. The TX2-60 HE complies with protection class IP 67, with all cables being routed inside the housing, from pedestal to gripper.

“We have already had good experiences with Stäubli on other projects, both in terms of support during the project planning and with the robots themselves,” says Bob Grote, CEO of Grote Company. “The hygienic design of this robot series was also a requirement. The entire cell is regularly sanitized with hot water and chemical cleaning agents.”

Whereas this routine would soon push a conventional robot beyond its limits, the Stäubli TX2-60 HE takes such rigors in stride.

Grote’s Robotic Sandwich Assembly Line can be integrated into existing production systems or operated as a stand-alone cell. The robot can take on additional tasks and produce various types of sandwiches with a quick program and gripper change.

Using a variety of pneumatic and mechanical grippers, the system achieves an impressive level of flexibility and is capable of handling both rectangular and round sandwiches as well as wraps. Grote says, “We are convinced that robotics will play a major role in automated food production in the future. We see ourselves as pioneers in this regard, and we intend to apply this principle in other areas, for example in the topping and handling of frozen pizzas.” NP

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