Mixed-width laminations change which vacuum zones contact steel and which remain exposed. Map coverage and branch pressure to establish the holding condition at every active contact throughout transfer.
Map part coverage onto the vacuum circuit
For each lamination family, map fully covered, partly covered and exposed contacts, including cutouts, steps and position scatter. Connect that map to real isolation elements, pressure sensors and the vacuum source; pressure force depends on local pressure difference and effective area. [1]
Represent the circuit in words or a drawing: source to monitored manifold, then branch isolation to each independently covered zone. Mark where an open contact admits air and which other zones can be affected. An isolation command in software is not evidence that the branch is physically sealed.
| Challenge state | Pressure observation | Retention observation |
|---|---|---|
| Narrowest intended part | Pressure at the active holding zones | Stable support at the actual contact pattern |
| Partly covered contact | Local and shared pressure response | Effect of positional scatter near an edge |
| One defined leakage branch | Isolation response and recovery time | Influence on neighbouring covered zones |
| Release and re-pick | Transient pressure history | Reliable establishment of the next holding state |
Use effective area and local pressure
The ideal normal holding force is pressure difference multiplied by effective sealed area. For an illustrative 40 kPa difference and 20 cm² effective area, the result is 40,000 Pa × 0.002 m² = 80 N. This fictional static value excludes seal deformation, dynamic demand, peeling, load distribution and the required design margin.
Area outside the lamination is not effective holding area. Nor can the full nominal contact area be counted if the seal is incomplete. For tangential loads, the contact friction and load direction also matter. A larger source vacuum does not cure a contact geometry that progressively peels open during motion.
Verify the narrow-part boundary
Record zone pressure during the actual qualified transfer and release sequence. Challenge the intended boundary conditions under a controlled commissioning procedure with suitable containment. Establish how the cell identifies an inadequate holding state and brings the process to its defined safe condition; do not bypass that function to complete a trial.
Catalogue gauge 0.23 mm and density 7,650 kg/m³ give 0.52785 kg for an assumed 1.0 m × 0.30 m lamination. [2] Its static weight is 5.18 N. The existing assumed 40 kPa and 20 cm² effective vacuum area provide an ideal 80 N normal force, a static ratio of 15.45. That ratio can collapse if a narrow part leaves a vacuum zone unsealed; if only 1 cm² remains effectively sealed, ideal force is 4 N, below the static weight. Enable and verify the covered zones for each width, then qualify dynamic, peel and fault conditions separately.
Width identification, pad sealing, vacuum-zone isolation and surface oil state control available holding force. Do not transfer a wide-sheet setting to a narrow variant solely because the same gripper is fitted.
Approve each part family against its coverage map, circuit state and measured retention through transfer transients. Use contact-level evidence to establish the required holding condition for that geometry.
References
- U.S. Department of Energy, DOE-HDBK-1012/3-92, Thermodynamics, Heat Transfer, and Fluid Flow, Volume 3, 1992.
- Nippon Steel Corporation, Grain-Oriented Electrical Steel Sheets, catalogue D004je, April 2020, specification and typical-property tables.