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tism

•Permanent magnets,

-external power is not required

-a mechanism is required to separate parts from the magnet when releasing

-good for environments that are sensitive to sparks

•Advantages,

-variation in part size can be tolerated

-ability to handle metal parts with holes

-pickup times fast

-requires only one surface for gripping

-can pick up the top sheet from a stack

•Disadvantages,

-residual magnetism that remains in the workpiece

-possible side slippage

39.4.3.1 - Adhesive Grippers

•Can handle fabrics and other lightweight materials

•These grippers are basically a sticky surface on the end of the robot

•As the adhesive gripper is repeatedly used, it loses stickiness, but a tape roll can be used to refresh the sticky surface.

39.4.4 Expanding Grippers

•Some parts have hollow cavities that can be used to advantage when grasping.

•A bladder can be inserted into a part, and then inflated. This forms a friction seal between the two, and allows manipulation. When done the pressure is released, and the part freed.

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• Expanding grippers can also be used when gripping externally.

bladders inflate inwards

39.4.5 Other Types Of Grippers

•Most grippers for manipulation are sold with mounts so that fingers may be removed, and replaced.

•Gripper fingers can be designed to reduce problems when grasping.