Cartons can look alike while behaving differently under vacuum. Recycled corrugated board may leak air through exposed fibers, seams, or crushed edges. On porous stock, a cup with a soft sealing lip or a larger contact area may help maintain grip. Yet a larger cup cannot always bridge deep flute marks. Test several locations on the actual carton.

Surface texture matters too. Glossy coatings can be smooth but uneven, while rough kraft paper may disrupt the seal. Check for dust, labels, tape, and printed areas where the cup will land. Easy to miss. A cup placed partly over a seam may hold during a slow trial and slip when the line accelerates. A clean sample can flatter the result.

Payload means more than carton weight. Include contents, cup orientation, acceleration, and the force from lifting or turning the package. Select cups with suitable load capacity, then verify performance at normal machine speed. Watch for gradual vacuum loss, carton deformation, and marks left on the surface. If results vary between batches, record the board type and test more than one carton. That extra check takes time, and it can still miss a rare defect.

Carton suction cups need to match the surface, not just the machine’s vacuum level. Paper dust can settle on the sealing lip and cause slow leaks. Dust changes everything. A soft, wide lip may seal better on rough board, while a clean, smooth carton can work with a firmer cup. Check for dust buildup during real production runs, not only on a clean sample.

No material wins in every condition. That chart can mislead. Carton coatings, dust levels, and cup pressure all change performance. Test several cups on production cartons, including dusty ones, and track missed picks and visible wear. Inspect the lip regularly; a small nick can turn a reliable seal into an intermittent problem. Temperature ratings and service life vary by compound and supplier, so verify the technical data before specifying a replacement.

A carton suction cup can hold firmly on a clean sample and still slip during a fast production cycle. Corrugated board leaks air through its surface, while warped flaps and dusty print areas make the seal less predictable. Test cups on the actual carton, not just a smooth test plate. Record vacuum level, airflow, pickup time, and release time across several cycles. Watch the carton corners. A small lift can become a dropped case when the conveyor accelerates.

ISO 4414 provides safety principles for pneumatic systems; it does not certify a cup’s gripping performance. Apply its risk-based approach to the vacuum circuit: provide accessible isolation, control stored energy, and prevent unexpected motion during maintenance. Check that tubing, valves, filters, and generators can supply the required flow without creating excessive pressure loss. Then run repeated pick-and-place trials at the intended speed, including the heaviest and most porous cartons. Keep a margin for wear and changing board quality. Real lines are rarely as tidy as test benches. One weak point is easy to miss: operators may adjust vacuum settings to mask a poor seal. Recheck the cause before raising the setting, and document the final test conditions.