Mixed-Case Palletizing: Planning for SKU Variation and Load Stability

Mixed-case palletizing places different products on the same pallet under a set of order, geometry, handling, and load constraints. A dense arrangement is useful only if the system can build it and the resulting load survives its intended handling.

NIST’s mixed-pallet metrics paper treats pallet quality as more than geometric packing. Our preparation tables translate that distinction into data to obtain before asking an integrator for a mixed-case proposal. They are planning aids, not a universal pallet acceptance standard.

Build a product record that describes the shipped case

Data group	Record per SKU	Why the planner needs it
Geometry	External packed dimensions, tolerances, bulges, allowed orientations	Defines the occupied envelope and possible placements
Mass	Packed mass range and unusual center-of-mass offsets	Supports load and tool review
Packaging behavior	Contact surfaces, stacking limits, weak panels, allowable compression	Identifies arrangements and grips to exclude or test
Identification	Barcode position, readability, alternate codes, label orientation	Connects physical cases to the correct data record
Order rules	Quantities, destination grouping, unload sequence, incompatibilities	Prevents a geometrically tidy but operationally unusable pallet
Handling conditions	Pallet type, wrapping, transport and storage environment	Defines what the finished load must withstand

Measure filled production packaging. A nominal carton drawing may omit tape seams, lid movement, or dimensional changes after filling. Mark an unknown as unknown and assign someone to obtain it; a default value can make a plan appear feasible for the wrong reason.

Define what the system knows before each pick

A planner that knows the complete order can arrange cases differently from one that must accept whatever arrives next. State whether the system can resequence products, how many cases can wait, and whether a requested SKU is available when needed.

If arrivals are fixed, the plan must respect that sequence or identify a buffer that changes it. If the planner requests a sequence, define the upstream equipment and control messages that deliver it. “Mixed-case capable” leaves this dependency unresolved.

Separate three feasibility checks

First, check the arrangement against the order and pallet restrictions: missing or duplicated cases, load envelope, allowed orientation, and required destination grouping.

Second, check buildability. The robot and gripper must reach the next placement without striking completed parts of the stack. A final arrangement can be geometrically valid while an intermediate placement is inaccessible.

Third, verify load behavior with representative filled cases. Review support, crushing, shifting, wrapping, and the intended downstream handling. A support-area calculation or low center of mass alone does not prove that the packaged contents and pallet will tolerate transport.

Test exceptions as well as favorable orders

Scenario	Evidence to collect
One required SKU arrives late	Buffer occupation, waiting time and recovery behavior
A barcode cannot be read	Reject or identification procedure and prevention of an incorrect placement
Actual size differs from the record	Detection, permitted tolerance and disposition of the case
A grip fails after planning	Replanning and reconciliation of the physical pallet with the order
The order cannot fit the allowed load envelope	How the system creates and labels an additional pallet
A pallet leaves partially built	Status record and the approved recovery or completion process

Use several actual order profiles, including inconvenient mixes. Record which restrictions each profile exercises. The simulation guide explains what can be checked in a model and what needs physical evidence.

Send the SKU records, sample orders, arrival logic, pallet rules, and product samples with the RFQ. The palletizing guides cover the cell and tooling choices that follow from those inputs.