Automated sandwich stacking solution

20 October 2020

Find out how and why a sandwich producer has successfully integrated robots into its sandwich production line.

Simple automation solutions can give some manufacturers the boost needed to increase production and product consistency. However, food manufacturing often poses a more complex application which may require intelligent, flexible robotic solutions that are able to adapt to product variation. 

In the case of one large-scale sandwich producer, growing production demands coupled with a labour shortage provided the motivation it look for better solution to solve its need for high-speed sandwich stacking. 

TechBrew Robotics, a Kawasaki Robotics preferred integrator based in Canada, was able to provide an automated solution, designing a customised solution using Kawasaki’s R series robots and F60 controller.

After the sandwiches are halved in the cutting machine, the robots need to pick up and rotate to stack one half on top of the other, making them easier for human workers to package manually further down the line. This was application was tricky to automate for a number of reasons – the sandwich halves vary in their position as they come out of the cutting machine, so the robot would need some sort of vision intelligence to recognise and understand the location of each half on the conveyor, all at very high speeds. 

The robot solution needed to be integrated into the existing production line, which required creative use of limited space. To this end, the R series robots were inversely mounted on a cantilever beam attached to the cutting machine. The compact size of the F60 controller made it possible to save more space by stacking them on top of the sandwich cutting machine itself. To maximise throughput, the robots face outward, stacking sandwiches on two different conveyors which are running simultaneously. There are many variables in this application, so TechBrew used a laser range finding system coupled with conveyor tracking to detect the shape and location of the sandwich halves as they emerge from the cutting machine. Once the sandwich halves have been stacked, they travel down the conveyor where human workers are waiting to pack the sandwiches into triangular cardboard boxes.

TechBrew designed a custom gripper specifically for this application. The pneumatic end effector is controlled directly by the controller, allowing for quick movements. A controllable pressure plate comes down to hold the product in place as two stainless steel paddles slide under the sandwich half to lift it. Once lifted, the actuator spins the sandwich half through 180°, and force dampers at the end of the rotation keep the sandwich and its ingredients intact.

Easy programming
It was possible to program the application directly on the robot, without the need for a co-processor – which reduced costs and simplified the installation. The Kawasaki F60 Controller’s high processing speed handled real-time scanning and data analysis on the sandwich halves, and output the robot coordinates in under 200 milliseconds, while processing a queue of sandwiches at a rate of 60 per minute. The entire sandwich stacking process takes just 800 milliseconds 

Obviously TechBrew had to consider national food safety regulations when designing this solution, and in this case it used the cleanroom version of Kawasaki’s 5 kg payload RS005L general purpose robot. As standard it offers a pressurised cavity, ISO Class 5 cleanroom specification, and comes with an aluminium arm cover, rubber outer seals and a chemical resistant epoxy paint finish for easy wash down. The patent-pending end effector’s tool-less design makes it easy to disassemble for cleaning purposes, and it is constructed with stainless steel and food-grade plastic.

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