Robotic gripper types: parallel jaw, vacuum, magnetic, soft
Choosing a robotic gripper starts with the workpiece, not with the arm. Four families cover almost everything a desktop or light industrial robot handles: parallel jaw, vacuum, magnetic, and soft or compliant. Each fails in a characteristic way, and knowing that failure mode in advance is what stops a cell from dropping parts.
A robotic gripper is chosen by the workpiece, not by the arm
Ask five questions about the part before opening any product page. How heavy is it? Is at least one face flat, smooth and non-porous? Is the material ferrous? How much can it be squeezed before it marks or deforms? And does it arrive in the same place and orientation every cycle?
Those answers usually eliminate three of the four families outright. A porous foam cube rules out vacuum. A plastic housing rules out magnets. A thin-walled cup rules out a hard parallel jaw at anything but the lightest force.
Then subtract the gripper's own mass from the arm's rated payload, because the two share a budget. An arm rated at 250 g fitted with a 150 g tool has 100 g left for the part. This catches people out more than any other line on a datasheet.
The four gripper families and what each one holds
Parallel jaw grippers
Two fingers close along a common axis and clamp the part between them. It is the oldest design in production robotics and still the default, because it is predictable: fingertip geometry defines the grip point, so a seated part sits in a known place relative to the flange.
Parallel jaws suit rigid parts with two roughly parallel faces: machined blocks, moulded housings, bar stock, printed parts. They also tolerate dust, oil and heat better than any other family, since nothing needs to seal or stick.
Their weaknesses are specific. Force lands on two small contact patches, so thin walls buckle and finished surfaces mark. Round parts squirt out of flat fingers unless the tips are cut with a vee. And jaws need clearance on both sides, so parts packed tightly in a tray can be unreachable.
Vacuum and suction grippers
A suction cup seals against a surface and a pump or venturi ejector lowers the pressure behind it, so atmospheric pressure holds the part on. Holding force scales with cup area and vacuum level, so one large cup or several small ones both work while the seal holds.
Suction is the fastest and gentlest option for anything with a flat, smooth, non-porous face. Sheet metal, glass, PCBs, boxed goods and acrylic all lift cleanly, and because the cup touches one face only it can pick parts sitting shoulder to shoulder.
The seal is the whole design, so anything that breaks it kills the grip. Porous cardboard, textured mouldings, tight curves, oily film and swarf all cause leaks. Suction is also directional: a cup holding a part firmly straight down may release it under sideways acceleration. Cups are consumables and harden with age.
Magnetic grippers
An electromagnet or a switchable permanent magnet attracts a ferrous part directly. There is no seal, no clamping force applied to the geometry and no need for a flat face, only a magnetically permeable one, so a magnet will hold a rough casting, a perforated bracket or a part still wet with coolant.
The catch sits in the release rather than the pick. Residual magnetism keeps a light part clinging after the coil switches off, so magnetic tooling usually adds a stripper plate or a brief reverse pulse. Magnets also grab whatever else is near, so picking one shim off a stack is unreliable. Aluminium, brass, plastic, most stainless grades and electronics are out.
Soft and compliant grippers
Soft grippers use flexible fingers, often silicone bellows driven by air, that wrap around a part and conform to it. Contact spreads over a large area at low pressure instead of concentrating on two points, so the object shapes the grip rather than the reverse.
That makes them the answer for produce, baked goods, irregular castings and anything fragile or variable. The WLKATA Fruit Picking Cell, $2,800 at the time of writing, pairs a 6+1 axis Mirobot with a three-finger soft gripper for exactly this work, with a one-year warranty on the arm.
Compliance cuts both ways. A soft gripper holds the part approximately rather than precisely, so accurate placement afterwards needs vision correction. Payload is low, cycles are slower because fingers take time to inflate and deflate, and silicone eventually tears.
Which gripper for which workpiece
Read across from the part you actually have, not from the gripper you already own.
| Gripper type | Best workpieces | Avoid on | Main failure mode |
|---|---|---|---|
| Parallel jaw | Rigid blocks, housings, bar stock, printed parts | Thin walls, polished faces, tightly packed trays | Marking or crushing the part |
| Vacuum and suction | Sheet metal, glass, PCBs, boxes, acrylic, labels | Porous, textured, oily or tightly curved surfaces | Seal leaks, then release under acceleration |
| Magnetic | Steel plate, castings, brackets, perforated stock | Aluminium, plastics, electronics, stacked thin sheet | Failure to release, or picking two parts |
| Soft and compliant | Produce, food, irregular or fragile mixed items | Precision placement, high payload, fast cycles | Imprecise part position after the pick |
The failure mode column is the one to design around. Cheap insurance is a sensor that confirms the grip: a vacuum switch on a suction line, jaw position feedback on a parallel gripper, or a camera check after the pick.
Quick-change tooling and adapters
Few real applications get by on one gripper. A cell sorting three part types may need a suction cup for the flat one and a soft gripper for the awkward one, which means either two arms or one arm that changes tools.
The WLKATA Mirobot Advanced Kit is $1,890 and includes five: a pen holder, a micro servo gripper, a suction cup, a two-finger soft gripper and a three-finger soft gripper. All five mount to the same wrist, so a class can swap tooling between exercises and compare results on identical parts, which is far more instructive than reading about the trade in a textbook.
Two practical notes apply to every tool change. Each end effector shifts the tool centre point, so the offset has to be redeclared or every taught position lands wrong. And each has its own mass, which eats into payload. A heavier gripper can quietly halve what an arm can lift.
Larger cells sidestep the problem by dedicating an arm per tool. The WLKATA AI Automatic Sorting Cell, $6,500, runs two 6+1 axis Mirobot arms at 0.2 mm repeatability with a 250 g standard payload, fed by an OpenMV camera module that identifies parts by colour, shape or code before either arm moves.
Teleoperated gripper control
Not every grip has to be programmed. Teleoperation puts a human hand in the loop, and for parts that defy scripted logic, such as tangled items or a mixed bin, that remains the fastest route to a working demonstration.
The Elephant Robotics myController S570 – Exoskeleton Controller is a wearable dual-arm device at $1,299, with 6 degrees of freedom per arm and 12 in total, 570 mm of reach per arm, 4096-count encoders, a data rate up to 100 Hz and latency of roughly 30 to 50 ms. It weighs 1.5 kg and carries a 365-day warranty on its mechanical, power and control systems.
Latency matters here because of grip timing. Closing a gripper by feel only works if the response arrives while the correction still applies, and tens of milliseconds is roughly where the hand stops noticing. Recorded sessions also become training data, which is how most imitation-learning work on manipulation is done.
Single-arm setups follow the same pattern with less hardware. The Elephant Robotics myArm C650, $859, is a hand-operated 6-DOF leader device that streams motion at 50 Hz to drive a follower arm.
Frequently asked questions
What is an end effector?
An end effector is whatever is bolted to the robot's wrist flange to do the actual work. Grippers are the most common type, but the category also covers suction cups, welding torches, dispensing nozzles, screwdrivers, cameras and pen holders. The robot arm only positions things. Every capability beyond motion comes from the end effector attached to it.
How much force should a robot gripper apply?
Enough to resist gravity and the inertia of the planned motion, with a margin, and no more. Higher force does not make a grip safer once slip is prevented; it only increases the risk of marking or crushing. Where a part is delicate, reduce acceleration first, since a slower move needs far less clamping force to stay secure.
Can one robot arm gripper handle several different parts?
Sometimes, if the parts share a family. Soft grippers cope with variation in shape better than any other type, and a parallel jaw with custom-profiled fingertips can serve a group of similar components. Once the parts differ in material or surface as well as shape, a tool changer or a second arm is usually more reliable than a compromise gripper.
Do soft grippers work for industrial production?
Yes, and they are widely used in food, produce and consumer goods packing, where the alternative was manual handling. What they do not do well is precision assembly. Because the part settles into an approximate position rather than a repeatable one, any downstream operation that needs tight placement has to add vision correction or a regripping station.
What does a vacuum gripper need besides the cup?
A vacuum source and a way to break it. That means either a pump or a compressed-air venturi ejector, tubing, a valve to release the part, and ideally a vacuum switch that confirms the seal before the arm moves. Without that sensor, a failed pick looks identical to a good one until the part is not where the program expects.
Matching tooling to a desktop arm
Pick the gripper for the hardest part in the set, not the easiest, and confirm the arm still has payload left once the tool is fitted. If parts vary widely, plan for a tool change or a second arm from the start. Add grip confirmation on anything that moves quickly.
Desktop arms, multi-tool kits and vision-guided workcells from Wlkata and Elephant Robotics are listed in the robotic kits and desktop arms collection. RoboticsSelect is an authorized dealer for both brands, so every unit arrives with the full manufacturer warranty and free US shipping.