Robot Gripper Types: End-of-Arm Tooling Explained (2026)
Robot gripper types explained — vacuum, mechanical (2/3-finger), magnetic, soft, and Bernoulli grippers — how each works, what they suit, and PLC control.
A robot gripper is the component that determines whether your automation cell actually works in production — the rest of the robot arm is just positioning. Choose the wrong gripper type and you get dropped parts, marking, cycle time overruns, or integration headaches at commissioning. This guide covers every major robot gripper type, the engineering logic behind each one, and — critically for controls engineers — how grippers are actuated and sensed from a PLC or robot controller.
What Is a Gripper / End Effector (EOAT)?
End-of-Arm Tooling (EOAT) is the collective term for any device mounted at the robot's wrist flange to interact with a part. The terms end effector, gripper, and EOAT are used interchangeably in industry, though strictly speaking "end effector" covers tools that do more than grip (welding torches, dispensing valves, deburring spindles), while "gripper" implies holding or transferring a workpiece.
EOAT sits at the intersection of mechanical design, pneumatics, and controls. From a PLC perspective, a gripper is typically a combination of:
- One or more actuator outputs (solenoid valve coils, servo drive commands)
- One or more sensor inputs (part-present, open/closed confirmation, vacuum level)
- Interlock logic that prevents robot motion unless the gripper state is confirmed
Understanding gripper types informs how you wire them, how you write the interlock rungs, and how you handle faults. For broader context on robot program structure, see the industrial robot programming complete guide.
Vacuum / Suction Cup Grippers
How they work: A vacuum generator (venturi or pump) pulls a partial vacuum through one or more elastomer suction cups. Atmospheric pressure on the back face of the part provides the clamping force. Releasing the part is done by venting the vacuum or applying a brief positive pressure blow-off.
Best suited for: Flat or gently curved non-porous surfaces — cardboard boxes, sheet metal blanks, glass panels, plastic injection moulded parts, food trays, and PCBs. Vacuum grippers dominate palletising, packaging, and press-tending applications.
Limitations: Porous materials (raw foam, uncoated timber, fabrics) leak air and collapse the vacuum. Parts with large holes present the same problem. Wet, oily, or very rough surfaces reduce cup adhesion. They also require clean filtered air and regular cup replacement.
Key variants:
| Variant | Use case |
|---|---|
| Single large cup | Uniform flat panels, glass |
| Multi-cup array | Large boxes, variable part sizes |
| Bellows cup | Curved or uneven surfaces |
| Foam-seal cup | Slightly porous or textured surfaces |
| Oval / rectangular cup | Sheet metal and door panels |
Controls wiring: A single solenoid valve (5/2 or 3/2) switches vacuum ON and blow-off ON. The robot controller or PLC drives the solenoid coil through a digital output. A vacuum switch (analogue or digital threshold) feeds a digital input confirming vacuum level has been reached before the robot moves. Typical interlock: DO_GRIP_SOL := 1 → wait for DI_VAC_OK := 1 before issuing move command. For more on sensor types used in these feedback loops, see types of industrial sensors.
Mechanical Grippers
Mechanical grippers use driven fingers to physically clamp around or inside a part. They are the most versatile gripper family and the default choice when vacuum is not suitable.
Two-Finger (Parallel Jaw) Grippers
How they work: Two opposing jaws move in parallel planes, driven by a pneumatic piston or electric motor through a rack-and-pinion, lead screw, or toggle mechanism. The jaws can grip externally (outside of a part) or internally (inside a bore or pocket).
Best suited for: Machined parts, round stock, extrusions, and any part where a repeatable datum grip is needed. External grip is most common; internal (ID) grip is used when the outside surface is critical or cannot be marked.
Key parameters: stroke per jaw, grip force, repeatability, jaw opening at maximum stroke. Pneumatic parallel grippers are compact and fast. Electric (servo) parallel grippers offer programmable force, speed, and multiple grip positions from one device.
Three-Finger (Centric) Grippers
How they work: Three jaws close simultaneously at 120° spacing, centring the part automatically. Most designs use a scroll mechanism similar to a lathe chuck.
Best suited for: Round, hexagonal, and cylindrical parts — turned components, bottles, pipes, fasteners. The three-point contact self-centres without needing a fixture to locate the part first.
Limitation: Only practical for round or near-round profiles. Jaw change time is slower than a two-finger unit if frequent changeovers are needed.
Angular (Pivoting) Grippers
How they work: Jaws rotate on pivot pins rather than translate in parallel. The grip arc allows the jaws to reach around features that a straight parallel jaw cannot clear.
Best suited for: Parts with undercuts, flanges, or where the approach angle is restricted. Common in foundry tending and forging transfer.
Controls wiring for mechanical grippers: Most pneumatic mechanical grippers use a 5/2 solenoid valve: energise coil A to close (grip), energise coil B to open (release). Reed switches or inductive sensors mounted in the gripper body feed DI_GRIP_CLOSED and DI_GRIP_OPEN digital inputs. The PLC interlock confirms both states before allowing the robot to travel. Electric grippers connect via a fieldbus (IO-Link, EtherNet/IP) or direct digital I/O and expose position, force, and fault data.
Magnetic Grippers
How they work: An electromagnet or switchable permanent magnet (SPM) creates a magnetic flux that holds ferrous parts. Electromagnets turn on/off with a DC supply. Switchable permanent magnets use a mechanical or electrical mechanism to flip internal permanent magnet polarity, requiring power only during switching, not during holding.
Best suited for: Steel and cast-iron parts — stampings, sheet metal, automotive body panels, structural sections, and flat bar stock. Magnetic grippers handle hot parts (post-press, post-weld) that would damage rubber cups.
Limitations: Only ferrous metals. Non-ferrous aluminium, stainless 300-series, brass, plastics — no attraction. The gripper must be sized so residual magnetism does not prevent part release; switchable permanent magnets address this cleanly.
Controls wiring: Electromagnets use a DC contactor or solid-state relay driven from a digital output. Switchable permanent magnets use a brief current pulse (100–500 ms) to switch state. A current or voltage feedback signal confirms magnet energisation. Part-present sensing is typically an inductive proximity sensor detecting the part in contact with the magnet face.
Soft / Adaptive Grippers
How they work: Soft grippers use compliant, flexible fingers — silicone, polyurethane, or textile-reinforced inflatables — that conform to irregular part geometry under light pneumatic or hydraulic actuation pressure. There is no rigid jaw geometry; the finger wraps the part.
Best suited for: Delicate or irregular objects that rigid grippers would crush or cannot conform to — fresh produce, baked goods, irregular castings, consumer electronics housings, and lab samples. Collaborative robot (cobot) cells also favour soft grippers because the low impact force reduces injury risk.
Limitations: Lower maximum grip force than rigid grippers. Slower cycle times because the soft fingers must inflate and wrap. Not suitable for precision-located machined parts where repeatable datum contact is critical.
Key variants:
- Pneumatic bellows fingers — inflate to wrap around part
- Tendon-actuated fingers — cable-driven flexible links, often for small parts
- Gecko-adhesive pads — van der Waals adhesion for smooth surfaces without vacuum
- Jamming grippers — granular material in a membrane; vacuum applied to "jam" the granules around the part shape
Controls note: Soft grippers driven by pneumatic inflation use a proportional pressure regulator or on/off valve. Pressure feedback (analogue 4–20 mA transducer) monitors grip quality. Excessive pressure trips a fault. For the integration of these sensors into PLC programs, the material handling PLC programming guide covers the relevant I/O structure.
Bernoulli Grippers
How they work: A Bernoulli gripper uses a high-velocity air flow across a disc-shaped surface to create a low-pressure zone (Bernoulli effect). The part is held by the pressure differential without physical contact. The gripper levitates the part on a thin air cushion rather than clamping it.
Best suited for: Semiconductor wafers, glass panels, thin film displays, and any flat part that must not be contacted on its top surface. Non-contact handling eliminates surface contamination and prevents fragile parts from being marked or scratched.
Limitations: Only effective for flat, relatively rigid parts. The part must be presented in a controlled orientation. Grip force is low and dependent on maintaining continuous airflow. Not useful for heavy or porous parts.
Controls wiring: A proportional valve or fixed orifice supplies the air. The gripper state is confirmed by a laser or optical distance sensor detecting the part within the levitation gap. There is no physical contact feedback — the controls logic must rely on the sensor rather than a mechanical switch.
Needle / Pin Grippers
How they work: An array of needles or pins driven by a pneumatic actuator pierces or entangles the surface of the material to hold it. No vacuum, no clamping — the mechanical interference between pins and the material fibres or foam cells provides the retention force.
Best suited for: Textiles, insulation batts, foam, carpet, and fibrous composite preforms that are too porous for vacuum grippers and too soft for rigid mechanical jaws.
Controls wiring: A single solenoid drives the pin array in and out. End-of-stroke reed switches confirm the extended (engaged) and retracted (released) states.
Gripper Selection Criteria
Selecting the right gripper type is a decision matrix driven by the part and the process:
| Factor | Questions to answer |
|---|---|
| Part material | Ferrous? Porous? Delicate? Rigid? |
| Part geometry | Flat, round, irregular, with holes? |
| Part weight | Determines required grip force and safety factor |
| Surface condition | Clean, oily, hot, wet, textured? |
| Cycle time | How fast must the gripper open/close/confirm? |
| Required accuracy | Datum grip needed, or "good enough" placement? |
| Contamination risk | Food, pharma, cleanroom — no contact preferred? |
| Part fragility | Can the surface be touched, marked, or loaded? |
| Changeover frequency | Single product or multi-product cell? |
A general decision path:
- Flat non-porous surface → vacuum cup first choice
- Ferrous metal, no surface marking concern → magnetic
- Round or prismatic machined part → mechanical parallel or three-finger
- Fragile, irregular, or delicate → soft/adaptive
- Flat, no contact allowed → Bernoulli
- Porous fibrous material → needle/pin
Pneumatic vs Electric Grippers
Most production grippers are pneumatically actuated. Electric (servo-driven) grippers are growing rapidly, particularly in collaborative robot cells.
| Pneumatic | Electric | |
|---|---|---|
| Speed | Very fast (< 100 ms typical) | Moderate (100–500 ms) |
| Force | Fixed by air pressure and bore size | Programmable in software |
| Positions | Open / closed (two states) | Infinite within stroke |
| Feedback | Reed switches, vacuum switch | Encoder position, torque |
| Power off behaviour | Can spring-return to safe state | Requires brake or hold logic |
| Fieldbus | Valve island (DI/DO) | IO-Link, EtherNet/IP, ProfiNet |
| Best for | High-speed production, simple I/O | Multi-product, force-sensitive, cobot |
From a PLC perspective, pneumatic grippers are simpler to wire and commission. Electric grippers expose far richer data — position, grip force, velocity profile — which enables force-controlled assembly and adaptive gripping but requires more integration effort. Understanding the difference between these actuation approaches connects directly to how you structure robot I/O in programs for applications such as how robotic arms work.
Tool Changers
A robotic tool changer (also called an automatic tool changer or ATC) is a quick-release coupling at the robot wrist that allows the robot to pick up, swap, and release different EOAT automatically — without human intervention or cell downtime.
Master plate mounts permanently to the robot wrist. Tool plate mounts to each gripper. A pneumatic locking mechanism secures the two halves with defined retention force. Electrical, pneumatic, and fieldbus utilities pass through the coupling.
Tool changers are common in multi-product cells where a single robot runs different parts across shifts, and in robot palletizing cells where different pallet patterns require different cup arrays. The controls requirement is simple: a digital output activates the lock/unlock valve, and a sensor confirms a valid lock before robot motion is permitted.
How Robot Grippers Are Actuated and Sensed
This section addresses the controls integration specifics that matter to PLC and robot programmers.
Solenoid Valve Control
For pneumatic grippers, the solenoid valve is the primary actuator output. A 5/2 double-solenoid valve provides explicit control of both directions: energise coil A (grip), energise coil B (release). A 3/2 single-solenoid spring-return valve energises to grip and spring-returns to release on power loss — the safer default for drop-on-fault applications.
The solenoid coil draws 0.5–2 W typically. Drive it directly from the robot controller's digital I/O (24 V DC sourcing or sinking) or from a PLC output card through a valve island.
Part-Present Sensing
Before the robot commands a pick, a part-present sensor confirms the part is at the target location. Common types:
- Inductive proximity sensor — ferrous/non-ferrous metal parts at 1–20 mm range
- Capacitive proximity sensor — any material, including plastics and liquids
- Diffuse photoelectric sensor — any surface colour, longer range
- Laser distance sensor — precise positioning, detects part height variation
The sensor output feeds a digital input (DI_PART_PRESENT). The robot program or PLC logic waits for this signal before issuing the close command.
Vacuum Level Feedback
Vacuum grippers require a vacuum switch or analogue vacuum transducer to confirm adequate seal before the robot lifts. A digital vacuum switch (set-point factory-adjusted or field-programmable) provides a single DI_VAC_OK bit. An analogue transducer provides a 4–20 mA or 0–10 V signal that the PLC can use to monitor vacuum level continuously and detect slow leaks developing over time.
Gripper Open/Close Confirmation
Mechanical grippers use reed switches or Hall-effect sensors embedded in the gripper body at the fully open and fully closed positions. These feed DI_GRIP_CLOSED and DI_GRIP_OPEN digital inputs. The interlock logic must confirm the correct state before allowing robot motion — confirming closed before a carry move, confirming open before a place move.
Interlock Logic Example
A typical PLC rung structure for a pick sequence:
- Robot output signals
DO_MOVE_COMPLETE(robot at pick position) - PLC confirms
DI_PART_PRESENT = 1 - PLC sets
DO_GRIP_SOL_CLOSE = 1(valve coil A energised) - PLC waits for
DI_GRIP_CLOSED = 1(maximum 500 ms, else fault) - PLC sets
DO_ROBOT_PROCEED = 1(robot may now carry) - Fault condition: if
DI_GRIP_CLOSEDnot received within timeout, PLC setsDO_ROBOT_E_STOP = 1and raises alarm
This pattern — command out, confirmation in, timeout fault — is the core interlock structure for all gripper types regardless of actuation method.
FAQ
What are the types of robot grippers?
The main robot gripper types are vacuum/suction cup, mechanical (two-finger parallel jaw, three-finger centric, and angular variants), magnetic (electromagnetic and switchable permanent magnet), soft/adaptive, Bernoulli (non-contact air levitation), and needle/pin grippers. Each suits different part materials, geometries, and handling requirements.
What is EOAT?
EOAT stands for End-of-Arm Tooling — any device mounted to a robot's wrist flange to interact with a part or process. Grippers are the most common EOAT category, but the term also covers welding torches, dispensing valves, deburring spindles, screwdrivers, and inspection cameras.
What is the difference between a vacuum and mechanical gripper?
A vacuum gripper holds parts using atmospheric pressure against a suction cup — no physical clamping force is applied to the part sides. It suits flat, non-porous surfaces and is fast and gentle. A mechanical gripper applies direct clamping force through driven jaws, making it suitable for round, irregular, or porous parts where vacuum cannot form a seal. Vacuum grippers are more susceptible to surface condition and part geometry; mechanical grippers are more susceptible to part marking and require closer tolerance on part geometry.
How are robot grippers controlled from a PLC?
Pneumatic grippers are controlled through solenoid valve outputs (digital I/O, 24 V DC) wired to the PLC or robot controller's output cards. Confirmation is provided by reed switch or inductive sensor inputs at the open and closed positions. Vacuum grippers add a vacuum switch input confirming adequate seal. Electric grippers communicate over a fieldbus (IO-Link, EtherNet/IP, ProfiNet) and expose position and force data. In all cases, the PLC interlock logic must confirm gripper state before permitting robot motion to prevent dropped or crushed parts.
