Food for thought: Robot stacks
sandwiches in 800 milliseconds
Although simple automation can
give some manufacturers the boost
needed to increase production and
product consistency, more complex
applications often require intelligent,
flexible robotic solutions that can
adapt to variable products and picking
locations. In the case of a large-scale
sandwich producer, growing production
demands coupled with a major labour
shortage provided motivation for
them to robotically automate a highspeed
sandwich stacking application.
To resolve the challenge, TechBrew
Robotics, a Kawasaki Robotics Preferred
Integrator based in British Columbia,
Canada, designed a custom solution
using Kawasaki’s R series robots and
F60 controller.
The robots’ task may seem simple: 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. However, this 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. They
also needed to be able to stack the
sandwiches in practically the blink of an
eye.
Because TechBrew needed to integrate
its solution into the customer’s
existing production line, it meant
making creative use of limited space.
To this end, the R series robots were
inversely mounted on a cantilever
beam attached to the cutting machine,
and the F60 controllers’ compact
size made it possible to save further
space by stacking them on top of
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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 to a place where
human workers are waiting to place the
product into triangular cardboard boxes.
TechBrew designed a custom gripper
specifically for this application. The
pneumatic end effector is controlled
directly by the F60 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.
Like many other manufacturers, the
customer struggled, sometimes daily,
to keep up with production goals
due to absent workers. “The main
driver for the end user here was the
frequent shortage of labour. Their
production lines were understaffed,
and they were always missing people
from their optimum shift capacity,”
says Kyran Findlater, Mechatronics
Designer at TechBrew. Obviously
TechBrew had to consider national
food safety regulations when designing
this solution, and in this case the
integrator used the cleanroom version
of Kawasaki’s 5 kg payload RS005L
general purpose robot. As standard it
offers a pressurized 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.
The combination of Kawasaki’s
AS programming language and its
F60 controller easily handled the
complexities of this project. Findlater
was able to program this application
directly on the robot, without a coprocessor,
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 and
according to TechBrew, it didn’t take
the customers’ line managers long to
adjust to their new robotic co-workers.
Throughput has increased significantly
as a result of the robot’s consistency.
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