Robot suction cups: match the cup to the part

Evaluate the real surface before the cup diameter

Robot suction cups should be selected around the actual contact surface and motion, not just the workpiece weight. Cardboard, molded plastic, coated metal, and flexible film present different challenges. Seams, labels, ribs, curvature, and porosity can matter as much as the material name on a drawing.

Piab organizes its cup range by application and surface requirements, including cartons, rough surfaces, delicate parts, and other use cases. Use that kind of classification to assemble a realistic sample set. Request parts from normal production, including the surface changes your team sees between suppliers, batches, and storage conditions.

Read the force data in its stated conditions

A cup’s catalog force is not a guaranteed payload for an arbitrary robot path. Schmalz distinguishes theoretical suction force, shear force, and test conditions in its technical data. The complete system needs review for the chosen vacuum level, seal, cup arrangement, acceleration, orientation, and applicable design margins.

Ask the supplier to identify the load direction in each stage of the cycle. A horizontal transfer after a vertical lift can change the demands on the grip. Have the tooling designer review off-center loads and the condition of each cup. Do not divide part weight by the number of cups and treat the result as the entire engineering calculation.

Lay out the cups around the part and the process

Mark allowed pickup zones on the part drawing. Identify weak areas, openings, textures, printing, and surfaces where marks are unacceptable. Then evaluate cup spacing, support, compliance, and access to the destination. A large cup can be difficult to seal on a curved area; several smaller cups introduce their own plumbing and layout questions.

For case palletizing, test realistic carton fill and panel stiffness. For a formed tray, inspect whether the tool deforms the part enough to affect placement. Ask how the proposed design handles an uncovered cup or a workpiece that only partially contacts the tool. The required behavior should be demonstrated rather than inferred from a photograph.

Include generation, detection, and release

The quotation should identify the vacuum generator or pump, valves, tubing, filters, sensors, and release method. These components affect the interval between touching the part and obtaining a confirmed grip, as well as the time to release it. Ask for measurements from the complete tool instead of comparing only catalog component response times.

SMC’s vacuum-pad selection guide recommends testing with actual equipment and describes considerations including workpiece balance and transfer conditions. Turn that guidance into a written trial plan. Record grip confirmation, transfer outcome, release behavior, and the response to a failed seal. Let the qualified cell designer define safe test procedures and fault responses.

Test variation, not one perfect pickup

Build a matrix with part variants on one axis and operating conditions on the other. Include typical contamination, allowed height variation, relevant temperature conditions, and the range of orientations the tool encounters. Decide which combinations are representative and which are boundary cases requiring supplier review.

If the trial reveals inconsistent sealing, investigate the surface, cup placement, vacuum system, and presentation together. Increasing vacuum is not automatically the best correction. Compare a mechanical grip using our parallel-gripper design guide when contact zones or surface behavior make vacuum difficult. The objective is a reliable transfer, not proving a preferred technology can be made to work.

Budget for consumables and maintenance

Ask for cup part numbers, replacement criteria, inspection access, and an initial spare-parts list. Establish how maintenance will recognize deteriorating seals, clogged filters, damaged tubing, or a release problem. A low-cost consumable can become expensive if replacing it requires dismantling a tool or interrupting a long production run.

Include the vacuum tool and all carried equipment in the payload and reach review. Bring the sample matrix and tooling assumptions to a consultation. The final purchasing decision should rest on documented transfer performance, a maintainable design, and a clear list of conditions that were actually tested.

Build the vacuum-tool requirement into a FAIRINO quote

For a FAIRINO handling cell, bring the tested cup arrangement, vacuum equipment, tool weight, and part variation into the robot selection conversation. The FAIRINO comparison table helps organize candidate payload and reach figures; the complete transfer still needs review. Include grip confirmation and release timing in the quote so the proposed arm and vacuum system are evaluated as one application. Use our FAIRINO selection guide, then request a quote for your FAIRINO handling cell.