How to Choose a Mechanical Gripper: Parallel, Centric and Flexible Designs

When selecting a mechanical gripper, first choose the opening-and-closing motion, then the contact structure. Parallel and centric describe how the fingers move; flexible describes how they deform to follow a contour. These features can be combined, with selection based on workpiece shape, positioning requirements and handling loads.

⚙️ How do parallel, centric and angular grippers differ?

A two-finger parallel gripper moves its fingers toward each other along straight paths, allowing gripping from opposite sides. Flat surfaces, V-grooves or custom finger profiles can accommodate both rectangular and round parts. Suitability depends on the finger contact design.

A three-finger centric gripper closes its fingers synchronously toward a common center, making it suitable for centering round or cylindrical workpieces. An angular gripper opens and closes by pivoting its fingers, which can provide clearance during approach and release. However, the gripping location changes with the finger angle.

🤏 How do you choose between rigid fingers, soft pads and flexible fingers?

Rigid fingers establish contact through defined gripping surfaces, allowing locating features to be designed around the workpiece. They suit tasks with consistent part geometry and clearly defined placement orientations.

Adding soft pads to rigid fingers provides cushioning through local compression and changes the frictional properties of the contact surface. Their effect depends on the material, thickness and surface condition.

Flexible fingers deform to follow a contour, making them suitable for objects with shape variations that require gentle contact. In a Fin Ray finger, flexible side bands and internal ribs deform together to accommodate the contour at the contact region.

🔧 Can a parallel gripper use flexible fingers?

Yes. The parallel mechanism transmits and guides motion, while the flexible fingers adapt to the contour after contact. “Parallel” and “flexible” can therefore describe the same gripper, serving different motion and contact functions.

Final selection also needs to account for workpiece mass, motion acceleration, finger length and allowable contact force. The opening determines whether the workpiece fits; the contact structure affects how it is held; and the positioning requirements determine whether more clearly defined geometric constraints are needed.

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