Mechanical
Gripper
A gripper is end-of-arm tooling that grasps, holds, and releases a part, either by closing jaws or fingers on it or by holding it with suction.
What it is
A gripper is the most common kind of end effector: the tool at the robot flange whose job is to pick a part up and let it go. Mechanical grippers close two or three jaws, or a set of fingers, on the part. Vacuum grippers hold it with suction cups. Magnetic grippers turn up for ferrous sheet.
Choosing one comes down to the part: its weight, its shape, the surface it offers, and how much clearance there is around it for jaws to close.
How it actually works
A pneumatic gripper opens and closes on compressed air switched through a solenoid valve, often on a manifold near the wrist so the air lines to the tool stay short. Electric grippers drive the jaws with a motor and can report jaw position, which helps when one tool handles several part sizes. Either way, the program fires an output to close, then waits on a sensor input (jaw closed, part present, or vacuum made) before the robot moves.
The grip has to hold through acceleration and hard stops as well as at rest, so grip force is sized to the dynamic load. The gripper also counts against the robot's payload: its mass and center of gravity, plus the part's, go into the payload schedule. Get that data wrong and collision detection is working from a bad model, which is the most common false trigger for SRVO-050.
How it differs
- End effector · End effector covers anything mounted at the flange: a welding torch, a spindle, a dispensing nozzle, a camera. A gripper is the subset that holds a part. A welding robot has an end effector and no gripper.
- Vacuum gripper · A vacuum gripper is one kind of gripper. Mechanical jaws grip on geometry, so they handle porous, oily, or open-frame parts a suction cup can't seal against, but they need room around the part to close. Suction needs only a face to seal on, which is why it dominates cartons and sheet.
Where you meet it in the field
- Pick and Place · The plainest gripper job: grasp, move, release, at a rate partly set by how fast the gripper confirms a hold.
- Machine Tending · Dual grippers let the robot pull a finished part and load a raw one in a single trip to the machine.
- SRVO-009 Pneumatic pressure alarm · On cells that monitor air supply, low pressure to a pneumatic gripper shows up here through the PPABN input.
- Payload and Load Estimation Setup · Where the gripper's mass and center of gravity, and the part's, get entered so motion and collision detection match the real load.
Common questions
- How do I tell whether a mechanical or vacuum gripper suits my part?
- Start with the surface. A flat, smooth, non-porous face suits suction. A part with edges or features the jaws can close on, and space around it for the fingers, suits a mechanical gripper. Porous, oily, or open-frame parts usually rule suction out.
- Why does my part slip during fast moves when the gripper holds it fine at rest?
- The grip is sized to the static weight. Acceleration and hard stops add inertial load, and a long or offset part adds a turning moment at the fingers. Raise grip force, add finger features that locate the part, or soften the acceleration on the moves where it slips.
- Does the gripper's weight count toward the robot's payload?
- Yes. The rated payload covers everything at the flange: tool, adapter plates, and the part. Enter the gripper and the part in the payload schedule, with their centers of gravity, so the controller's motion planning and collision detection model the real load.