Automation Supplement

Pick and Place Applications – What Does “Faster” Mean?

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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.

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 affordable.

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 said.

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 down.”

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.

Resource List

Kuka Robotics Corporation (Clinton Township, Mich.); 866-873-5852

RobotWorx (Marion, Ohio); 740-383-8383

Staubli Corporation, Robotics Division (Duncan, S.C.); 864-433-1980

Wittmann Canada Inc. (Richmond Hill, Ont.); 888-466-8266