Grippers, end effectors and sensors make the robot. No matter how sophisticated the programming of this powerful equipment, unless the product to be manipulated is handled the way its physical properties dictate, the robot is no better than a trained gorilla wearing gloves.
That’s the principle behind piezoelectric technology, which measures changes in pressure, acceleration, strain or force and converts them to an electrical charge suitable for the safe handling of products of any size, configuration or delicacy. Piezo is Greek for 'press' or 'squeeze'. With the appropriate combination of proximity, position and distance sensors, a piezo-equipped robot can be suited to a wide variety of material handling applications.
The challenge with robotic grippers
The challenge with robotic grippers is the gentle handling of discrete items. As the trends to miniaturization in the consumer electronics industry and toward smaller form factors in food and life sciences continue, small scale manipulation is becoming more important—opening applications for Parker’s Piezo Gripper concept. This technology is particularly suitable for processes that are neither nano nor macro, but somewhere in between.
The fine motor handling of delicate objects—especially in food processing and pharmaceutical industries—has been a hit and miss affair. You not only don't want to mar the product, but you also want to prevent any kind of sticking between the product and the end effector.
With Piezo technology used in candy production, for example, a robot can transfer a sticky chocolate covered confection to a transfer point and, with a quick burst of power and a high frequency oscillation, release that product from the gripper without causing damage.
This methodology is hygienic, as there is minimal handling of the product, and because gross movements are minimized, lighter, more fragile kinds of products are transferred intact. Ideal applications in the food industry include lunch meat, cookies, pouches of dried fruit or cereal, juice or milk cartons and sacks of flour or sugar.
In the pharmaceutical and chemical industries, human contact with products in production is to be avoided for both safety and security reasons. Piezo gripper technology can be used to handle delicate vials containing expensive and climate sensitive products. Even expensive reagents consumed in the biosciences industry can be transferred from production to packaging without danger to the product or to those who would handle it.
Energy efficient piezo technology
Piezo technology is energy efficient. It is powered by a 12 or 24 volt signal, which is extremely low compared to other electric grippers. Power draw is also low, clocking in at 0.15 amps, which is about 10 times less than other electric grippers. The maximum gripping force is 1.235 Newtons, and because the power source is electromechanical rather than pneumatic, the added expense of compressed air is avoided.
Piezo technology is rugged, offering a lifespan of up to 500,000,000 cycles, compared to that of other products rated at 5,000,000 cycles.
As this technology finds a home in automated factories, Parker is researching other applications requiring its delicate touch and motion. This may eventually include the supplementation of human motion for those who are physically disabled. Stay tuned to Parker as they apply their engineering imagination to a world of emerging needs. In the meantime, visit our Pneumatics Division North America for more products and information on applications.
Article contributed by Richard McDonnell, Market Development Manager, Automation, Parker Hannifin
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