The gripper is the interface between a robot and the workpiece — and more automation projects fail on gripper selection than on any other component. A gripper that is too weak drops parts; one that is oversized adds weight, cost and cycle time. This guide covers the decision process for selecting a SCHUNK gripper, starting from the part you need to handle.
1. Understand the Gripper Families First
Industrial grippers differ mainly by jaw motion. Each family suits a different set of parts:
| Family | Motion | Best for | SCHUNK examples |
|---|---|---|---|
| Parallel gripper | Jaws move in parallel | Cuboidal and flat parts, precise positioning, most common choice | MPG-plus, PGN-plus, DPZ-plus |
| Angular gripper | Jaws pivot at a joint | Handling parts with a central bore or recess, limited space | JGP series |
| 3-jaw centric gripper | Three jaws close to centre | Round parts, centring tasks, machine loading | JAK, SDF series |
| Long-stroke gripper | Wide parallel stroke | Large or multiple parts per cycle | LGP series |
2. Calculate the Required Gripping Force
This is the number that decides the size — and it is a calculation, not a guess. The required force depends on the weight of the workpiece, the friction between jaw and part, and the acceleration of the robot:
- Basic holding force: F = m × g (for vertical grip: part weight × gravity)
- Acceleration factor: multiply by the expected acceleration of the robot arm (typically 1.5–3× for standard cells, more for high-speed handling)
- Friction factor: divide by the friction coefficient between jaw material and workpiece (0.1–0.3 for steel on steel, higher for rubberised pads)
- Safety factor: apply at least 1.5–2× additional margin
Example: a 2 kg steel part handled vertically with a friction coefficient of 0.2 and 2× acceleration needs roughly 2 × 9.81 × 2 ÷ 0.2 × 2 ≈ 390 N of gripper force. The gripper datasheet lists the force per jaw — always compare against the total required force and check the force curve at the actual jaw opening, because gripping force drops as the stroke opens.
3. Match the Stroke to the Part
Stroke per jaw must clear the part's diameter/width with a little margin for pick-and-place tolerance. Oversized stroke costs force and speed; undersized stroke makes the gripper unusable. If your parts vary widely in size, a long-stroke gripper or a parallel gripper with a large stroke range beats a dedicated single-size unit.
4. Check Jaw Length and Moment Loads
Long fingers amplify the gripper's moment load. Every gripper datasheet has a maximum permissible jaw length and moment ratings (Mx, My, Mz). Using fingers longer than specified risks jamming or damage. If your fingers must be long, either shorten the fingers, add a guide, or step up to a larger gripper with higher moment capacity.
5. Decide on Internal or External Gripping
- External gripping — jaws close around the part; most common, most stable
- Internal gripping — jaws open into a bore or recess; useful for parts that must be picked by their inner diameter, such as gears and rings
Check that the gripper supports your approach and that the jaw tips suit the part geometry (V-shapes, pads, custom fingers).
6. Choose the Sensing and Control Version
- Position sensing — versions with integrated inductive sensors (the -IS suffix) detect jaw position directly without external switches, simplifying wiring and machine integration
- Vacuum-compatible versions (-V suffix) are sealed for vacuum environments
- Actuation — pneumatic grippers dominate for speed and cost; electric grippers offer adjustable force and position control for delicate or varying parts
7. Consider the Environment
Verify the operating temperature range, IP protection, and resistance to cutting fluids and chips in machining environments. For cleanroom or food applications, check the specific cleanroom/food-grade versions of the gripper family.
8. SCHUNK Series as a Reference
SCHUNK's naming makes selection easier once the family is chosen:
- MPG-plus — miniature parallel grippers for small parts and confined spaces (e.g. MPG-plus 16)
- PGN-plus — the standard universal parallel gripper family, covering most industrial loads (e.g. PGN-plus-P 40-AS-K)
- DPZ-plus — parallel grippers with high force-to-weight ratio for demanding handling (e.g. DPZ-plus 40-IS-V)
- JGP — angular grippers for parts with bores and limited space (e.g. JGP-P 40-IS)
Browse the complete gripping systems category for the full range.
Buying Guide for Glorient Customers
Glorient supplies genuine SCHUNK grippers with competitive pricing and worldwide delivery. To select the right unit:
- Calculate the gripping force from your part weight, acceleration and friction (see step 2).
- Choose the family (parallel / angular / centric) and confirm stroke and jaw length fit.
- Send your part details and force calculation via the quote request form — our engineers will confirm the correct model, sensing version and accessories within 24 hours.
Gripper selection is a force calculation plus a geometry check — get both right and the cell will run reliably for years. If you are unsure about the numbers, send us the part weight, dimensions and robot model and we will do the calculation with you.
Frequently Asked Questions
What is the difference between 2-finger and 3-finger grippers?
A 2-finger (parallel) gripper handles parts with two opposing flat faces and is the most common for pick-and-place. A 3-finger gripper centres round parts and is preferred for cylindrical workpieces. 2-finger is simpler and cheaper; 3-finger self-centres but is bulkier.
How do I calculate the required gripping force?
The gripping force must exceed the part weight times the acceleration, divided by the friction coefficient between the fingers and the part, multiplied by a safety factor (typically 2 or more). Robot acceleration, part surface and orientation all raise the required force.
Should I choose a pneumatic or electric gripper?
Pneumatic grippers are simple, fast and low-cost but have limited force control. Electric grippers offer programmable force, position and speed, ideal for delicate or variable parts. Choose pneumatic for fixed high-speed tasks, electric for flexible or force-sensitive handling.