- Grippers, or end of arm tooling, devices enable the manipulation of an object.
- Precision mounting surfaces allow for the attachment of custom designed finger tooling.
- Selecting the right gripper can make automation projects easier.
A gripper is the mechanical or electrical End Of Arm Tooling (EOAT) device that enables the manipulation of an object. Or, in other words, it is a machine’s controllable “hand” that grasps and releases parts that are being moved by the automation. There are many different types and sizes of grippers designed to pick up a wide variety of parts and materials.
Most grippers have precision mounting surfaces for the attachment of custom designed finger tooling and also for accurately mounting the gripper to a robotic arm or “pick and place” unit. Grippers can be powered by compressed air, vacuum or electricity. Selecting the best gripper for your automation project will be much easier once you learn about the most common gripper types available.
1. Parallel Motion Two-Jaw Gripper
This is a very simple gripper utilized in many applications. Pneumatic, electric and hydraulic versions come in a large variety of sizes, forces, weights, and stroke ranges. They are generally used when you are grasping parts by two parallel, flat surfaces. They can grip a part by either the gripper’s closing or opening motion. There are also angular two-jaw grippers with 90-degree pivoting fingers that can completely retract and provide extra clearance that is beneficial for certain applications.
2. Three-Jaw Gripper
Also available in parallel and angular variants, this EOAT device is commonly used to pick up parts by a cylindrical surface. This type of gripper has three jaws spaced 120 degrees apart. Since it moves in unison, it “centers” the part in addition to providing a secure grip. It can also grip the part with either its opening or closing motion.
3. Bellows Gripper
Also used to grasp cylindrical surfaces, a bellows-style gripper utilizes an elastomer bladder to contact the part. It is inflated with compressed air causing it to expand and grasp the part. When the air is released, the bladder deflates and drops the part.
4. Collet and Expanding Mandrel Grippers
This EOAT device is use to grasp cylindrical surfaces by utilizing a linear motion and a wedge shape to open or close metallic fingers to grasp the O.D. or I.D. of a part.
5. O-Ring Grippers
This end of arm tooling is a specialty device designed to handle O-ring seals. Similar in operation to a three-jaw parallel gripper, the O-ring gripper has six or sometimes eight fingers that radially expand and grab the inside diameter of the O-ring. Once stretched, the O-ring can be placed by the machine into a groove on the end a cylindrical shaft.
6. Needle Grippers
This is a somewhat rare gripper variant designed to pick up porous or woven sheet materials, such as textiles, by penetrating the surface with multiple sharp needles.
7. Multi-Finger and Adaptive Grippers
A relatively new development, this design is enabling robots to grip a wide variety of products that were previously impossible to manipulate reliably. These grippers may provide force feedback to the controller and can also grasp irregularly shaped, soft or spherical objects.
8. Vacuum Cup or Vacuum Cup Arrays, Electromagnets, and Electrostatic Force Grippers
These types of grippers can also be employed by automation design engineers to reliably grasp and release parts.
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