Fundamentals of pneumatic grippers for industrial applications
in assembly or sorting and selecting, they’re often supported by sensor or even machine-vision systems to direct their actions. Otherwise, Hall Effect and proximity sensors in the gripper can provide sufficient feedback. Advantages and limitations of pneumatic grippers One key benefit of pneumatic grippers over other gripper types is that they’re available in numerous sizes and grip forces, ranging from a few Newtons to several kilo-Newtons, and can be adapted for different applications — even those requiring thousands of repetitions per hour. Industrial pneumatic grippers also offer unrivaled repeatability for precision automation tasks. In addition, pneumatic grippers: ■ Are cost and power effective to run ■ Are lightweight and compact — especially when compared to certain motor and hydraulic- based options Unlike their hydraulic and electric counterparts, pneumatic grippers are largely unaffected by their working environments. That’s in contrast with electrically actuated grippers with sensitive electronics than can malfunction in moist environments.
Of course, pneumatic grippers do have some drawbacks and limitations. These are primarily related to the operational cost and complexity of pneumatic designs and compressed-air systems in general. Initial setup of such systems can be costly and complicated. That said, there is economy of scale where an industrial operation already makes use of compressed-air systems elsewhere.
Pneumatic gripper selection criteria
Figure 3: Two-finger parallel grippers in Schunk’s PGN-plus series deliver long jaw strokes and include seals, dirt-resistant round linear guides, and high-strength aluminum-alloy housings to survive dirty industrial environments. (Image source: Schunk) is an asset — and pneumatically actuated finger grippers complement the use of other air-powered bladder and suction gripper types to handle everything from boxes and wine bottles to eggs and bags of candy. In contrast, grippers in machine- tool applications are typically designed for just one workpiece type — and in some cases, are even tasked with holding those workpieces as machining or other processes are performed. Where pneumatic grippers are involved
Sizing and specifying pneumatic grippers for a given material- handling application should start with the clear definition of key design parameters. Size and gripping force: Pneumatic grippers should open enough to accommodate the objects being handled. Required pneumatic-gripper finger force depends on the weight of objects being handled as well as the finger-to-object coefficient of friction, area of finger-to-object contact, and force to counteract that of the opposing fingers. Highly engineered gripper- finger materials and coatings can boost the finger-to-object coefficient of friction. Of course, the jaws of pneumatic grippers for use in food or pharmaceutical
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