ADVANCED MANUFACTURING NOW Ervin Vallejo
Advanced Synthetics for Kinder, Gentler Grippers a W
orkholding technology, including end-of-arm tool- ing on robots and other types of automation, typi- cally targets gripping and handling of mainly heavy,
robust metal components. But a growing number of today’s workpieces require a kinder, gentler touch. Product designers continue to combine the multiple parts of assemblies into single solid components to eliminate secondary operations and improve quality. They also incorporate more lightweight materials to enhance a product’s ergonomics and—in the case of automobiles, aircraft and other vehicles—to reduce energy consumption. Unfortunately, such product enhancements translate into workpieces that are odd shaped, highly complex and in many cases, extremely delicate.
For workholding OEMs such as Röhm, meeting today’s special delicate part demands has spurred new technological advancements, one of which is the use of synthetic poly- mer materials for end-of-arm robotic tooling/grippers and other automated part-handling systems. Because synthetic polymers are pliable, they envelop or “fl ow” with the shapes of parts, allowing them to grip a wide variety of workpieces as well as material types. Grippers made from synthetics are also more durable and lighter in weight.
Unlike mechanical grippers, synthetic ones can be a bit
more forgiving in terms of absorbing collisions and shocks while still maintaining their shape and integrity. And because the grippers are lighter, they help reduce overall automation tooling loads. Additionally, synthetic grippers can eliminate problems involved with optical and/or magnetic proximity sensors or systems. Synthetics provide contrast so that those sensors and systems can distinguish the difference between the workpiece and gripper. This is often a challenge when both the workpiece and tooling are made of metal. Consider a manufacturer that needs automation to grip metal hex nuts and transport them to a gauging station where they will be photo inspected. When standard metal mechanical grippers are used, robot optics could fail to dis- tinguish the difference between the metal gripper fi ngers and
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the hex nuts. Now, add a subsequent magnetic proximity switch station, and again, the automation could experience diffi culty in differentiating between the metal hex nuts and metal gripper fi ngers.
While metal/mechanical gripper solutions offer several advantages, manufacturing them is quite involved, thus mak- ing them a bit more expensive. Synthetic grippers, however, are now produced inexpensively using 3D printing and other such processes. For example, Röhm uses fi nite element analysis (FEA) in the design of its synthetic polymer grippers then quickly, easily and cost-effectively custom builds them with selective laser sintering (SLS).
Because synthetic polymers are pliable, they can grip a wide variety of workpieces as well as material types.
In fact, Röhm was an early adopter of synthetic gripper technology itself. The German-based company that invented drill chucks currently uses synthetic grippers to pick and place between 30,000 and 35,000 drill chucks per day in its own production operations. To provide the longest gripper working life possible, OEMs develop special proprietary blended synthetics to use for producing their grippers. These companies strive to achieve the one special recipe that achieves the most maintenance- free cycles, in some cases over 16 million. The future is wide open for synthetic gripper technology. Any light, complex workpiece that fi ts into the palm of one’s hand and requires careful gripping is a potential candidate. Industry segments, such as medical and electronics, con- tinue to drive the need for such delicate workpiece handling. There was a time when most manufacturers demanded
tooling strong enough to grip and hold such parts as drive shafts or big heavy castings. However, many of today’s manufacturers now want to handle components like fragile 1.5-mm-diameter medical catheters or automobile speed- ometer needles, and advanced synthetic gripper technology allows them to do so.
Automation Product Manager, North America
Röhm Products of America
www.rohm-products.com
MODERN MANUFACTURING PROCESSES, SOLUTIONS & STRATEGIES
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