Pick and Place Applications – What Does “Faster” Mean?
In the competitive world of plastics processing, a key to survival lies
in getting a part out of a molding machine and on to the next stage of production
as efficiently as possible.
For those applications in which the part doesn’t simply drop out the
bottom of the open mold cavity, this invariably involves some form of robotic
automation. And more and more often, molders are turning to pick and place
applications to perform the tedious, repetitive task of taking a part out
of the mold and placing it in the production line.
Pick and place robotic systems are finding themselves in a more favourable
competitive light as production lines move to greater varieties of products
moving at faster speeds.
According to automation integrator RobotWorx, pick and place systems
offer numerous advantages. “The speed of pick and place robots allows for
faster cycle times,” the company said. “Also, pick and place systems are
more accurate, reliable and consistent than their human counterparts: robots
can work 24 hours a day, seven days a week without stopping or tiring, and
pick and place robots can be reprogrammable and tooling can be interchanged
to provide for multiple applications.” The company also noted that, with
advancements in technology, pick and place robotic cells are becoming more
Jim Healy, vice president, sales and marketing with Sepro America, noted
that the control systems of many of today’s robots include many pick and
place routines that facilitate easy use. “Programming can often performed
by a relatively low-skill operator with little or no formal training,” he
Of all these advantages, speed is probably of paramount importance to
most molders. “The demand is absolutely for speed in the plastics industry,
where the less daylight time of the mold, the better off the molder is,”
said David Arceneaux, business development, marketing, for Staubli Corporation.
There is no doubt that pick and place robots are getting very fast indeed.
For example, Wittmann’s W721 UHS (ultra high-speed) servo robot, designed
for fast removal of parts from molding machines up to 300 tons, offers an
in/out motion of approximately 0.3 to 0.5 seconds, depending on conditions.
While the movement speed of the pick and place robot is important, and
often elicits the important “Wow” factor, automation suppliers are quick
to point out that speed, in and of itself, can be meaningless unless other
factors are taken into account. “It’s always tricky when someone gives you
information on pick and place robot speed because everyone calculates it
differently,” said Staubli’s David Arceneaux. “The true and legal way to
calculate the cycle time is the 1 inch by 12 inch by 1 inch U shape involved
in picking a part up, moving over and then going straight down. A lot of
companies do it differently, by rounding corners and not going all the way
Molders looking to purchase a pick and place application should also
keep in mind that the machines are designed for certain payloads, and that
the payload will affect the unit’s speed. The Kuka KR 5 Scara robot family,
for example, includes models that are designed for fast handling of payloads
up to 5kg.
According to Christian Weiss, Wittmann Canada Inc., in the end what matters
in the pick and place application is not so much speed as how fast the robot
can accelerate and decelerate to start and stop cleanly. ”The truly important
number is how fast the robot can get into the molding area, pick the part,
get out of the molding area and place the part – plus any downstream operations
– and then return to the start position for the next cycle,” he said.
Kuka Robotics Corporation (Clinton Township, Mich.)
RobotWorx (Marion, Ohio)
Staubli Corporation, Robotics Division (Duncan, S.C.)
Wittmann Canada Inc. (Richmond Hill, Ont.)