The choice between vacuum and mechanical gripping dictates cycle time, part-handling capability, and total system cost. A vacuum gripper like the OnRobot VGC10 offers faster cycles for flat, non-porous items, while a mechanical gripper like a Robotiq 2F-85 provides the dexterity needed for varied geometries. This decision is the single most important factor for end-of-arm tooling (EOAT) performance.
Key differences
The fundamental difference is how each gripper holds a part. Vacuum grippers use negative pressure (suction) to lift items from the top surface, making them ideal for objects like boxes or flat sheets. Mechanical grippers use fingers to physically grasp an object, providing a secure hold on parts with complex shapes, holes, or varied textures.
This distinction changes the entire application approach. Vacuum systems excel in speed for simple pick-and-place, executing cycles in under four seconds for palletising. Mechanical grippers offer more control for tasks requiring precise placement or manipulation, like loading a part into a CNC machine chuck.
Attribute comparison
The table below breaks down the core performance trade-offs we evaluate when designing a cobot cell. These specifications are based on common models like the Schmalz FXCB vacuum series and the OnRobot RG6 mechanical gripper. The right choice depends on your specific part and process.
| Attribute | Vacuum gripper (e.g. OnRobot VGC10) | Mechanical gripper (e.g. Robotiq 2F-85) | Why it matters |
|---|---|---|---|
| Typical payload | Up to 15 kg (VGC10) or 40 kg+ (Schmalz) | 2 to 6 kg (e.g. OnRobot RG2/RG6) | Vacuum scales higher for large, flat objects; mechanical is for lighter, complex parts. |
| Cycle time | Fastest (pick from top surface) | Slower (finger open/close time) | Critical for high-throughput tasks like palletising or case packing. |
| Part geometry | Flat, uniform surfaces (boxes, sheets) | Varied, complex, or uneven shapes | Determines which parts you can handle reliably. |
| Porosity tolerance | Low (needs non-porous surface for seal) | High (unaffected by porosity) | Crucial for handling cardboard, wood, or fabric. |
| Surface contamination | Sensitive to dust/oil (can break seal) | Tolerant to some debris | Defines suitability for dusty or oily CNC environments. |
| Energy source | Compressed air (ejector) or electric pump | Electric motor | Air consumption adds operating cost; electric is self-contained. |
| Collaborative safety | Excellent (compliant, low-force surfaces) | Good (needs force-limiting, soft tips) | Force exerted must be within ISO/TS 15066 limits. |
| Maintenance | Regular cup inspection, filter cleaning | Minimal (occasional re-greasing) | Affects total cost of ownership and planned downtime. |
Data sourced from manufacturer specifications and Olympus Technologies internal project data. These values represent typical off-the-shelf solutions.
Choose a vacuum gripper if
Your application involves handling flat, non-porous items like sealed boxes, plastic totes, or sheet metal. Vacuum systems are the default choice for high-speed cobot palletising where cycle time is the primary metric. Picking from the top surface avoids the need for side clearance, which simplifies cell layout.
You also need to handle large, lightweight panels without marking the surface. A distributed array of small vacuum cups can securely lift a large sheet with minimal pressure at any single point, preventing deformation or surface damage on sensitive materials.
Choose a mechanical gripper if
You are picking parts with varied geometries, holes, or inconsistent shapes, such as castings, machined components, or injection-moulded items. A two-finger gripper like the OnRobot RG2 can adapt its grasp to the part, a task impossible for a vacuum cup. This is essential for applications like CNC machine tending with cobots.
The part must be manipulated or placed with high precision. Mechanical fingers provide a defined, repeatable grip that fixes the part's orientation relative to the robot flange, which is critical for fitting components into a fixture or assembly.
Your parts are porous or have dusty surfaces. Materials like raw wood, open-cell foam, or dusty castings will cause a vacuum gripper to fail. Mechanical grippers are indifferent to surface porosity and work reliably where vacuum cannot maintain a seal.
When neither gripper is a perfect fit
The standard comparison assumes one gripper handles one part type. In reality, many production lines process multiple SKUs, or need a part handled in different ways during a single cycle. A press brake, for example, might need to pick a flat ferrous blank and then re-grip the bent component.
This is where off-the-shelf grippers show their limits. A simple vacuum head cannot handle a bent part, and a mechanical gripper may not be optimal for picking the initial flat sheet. Choosing one over the other creates a bottleneck, forcing a compromise on either speed or capability.
What if you need to handle both boxes and open bags?
A common challenge in food and beverage or FMCG is handling both a primary packed good (for example a bag of crisps) and the secondary cardboard case. A standard vacuum gripper that lifts a 10 kg box will likely damage a delicate bag, and a mechanical gripper gentle enough for the bag may lack the span or force for the box.
Here, a hybrid or custom gripper is the solution. We often design EOAT that combines small, low-force vacuum cups for primary packaging with a separate, high-flow set of cups for case handling. The robot's digital outputs select which vacuum circuit to activate, giving two-in-one functionality without a tool change.
How do you handle multiple part types in one cell?
For machine tending or assembly cells with a high product mix, a single gripper is inefficient. Changing a gripper manually between batches introduces downtime and erodes the ROI of the automation. The assumption that one gripper fits all is the most common failure point we see in flexible automation projects.
The answer is an automatic quick-change tool changer. This lets the cobot autonomously drop off a mechanical gripper and pick up a vacuum gripper in seconds. At Olympus Technologies, we integrate these systems so the robot can switch end-effectors as part of its program, enabling true lights-out manufacturing across different product families.
Alternatives and advanced gripping
When dealing with perforated steel sheets or raw ferrous blocks for press brake tending, neither vacuum nor mechanical grippers are optimal. A vacuum fails on perforated surfaces, and mechanical fingers can struggle with thin sheets. This is the ideal scenario for magnetic grippers for cobot machine tending, which provide a powerful hold regardless of holes or surface dust.
For applications needing precise insertion, polishing, or deburring, the gripper alone is not enough. These tasks need real-time feedback on the forces being applied. Integrating force-torque sensors on cobots lets the robot feel contact and adjust its path, preventing damage and ensuring consistent quality.
Frequently asked questions
How are grippers integrated with a Universal Robot?
Most certified grippers from brands like OnRobot or Robotiq connect directly to the cobot's M8 tool port and are controlled via a URCap. This software plugin adds simple commands like Open Gripper or Set Vacuum directly into the PolyScope programming environment. For bespoke systems, we wire the gripper to the robot's digital I/O and a PLC.
What is the difference between a vacuum ejector and a vacuum pump?
A venturi ejector uses compressed factory air to generate vacuum directly at the gripper, making it compact but less energy-efficient. An electric vacuum pump is a separate unit that provides a stronger, more consistent vacuum and uses electricity, which is often cheaper than compressed air. We specify pumps for high-payload or porous applications and ejectors for light, fast-cycling tasks.
Can a mechanical gripper be used collaboratively?
Yes, provided a risk assessment is completed to ISO/TS 15066. To ensure safety, we use grippers with built-in force limiting, rounded edges, and soft, compliant fingertips. The combination of gripper force, robot speed, and payload must stay within the standard's allowable limits for power and force-limited collaborative operation.
Talk to an automation expert
Choosing the right end-of-arm tooling is more than a spec-sheet comparison. It is about engineering a solution that matches your parts, process, and goals. If you are unsure whether vacuum, mechanical, or a custom solution is right for your application, our engineers can help.
Contact Olympus Technologies for a no-cost, no-obligation consultation to review your application and identify the most reliable and cost-effective gripping strategy.
