When to Use LPNs: Triggers and Timing for License Plate Number Assignment

Knowing when to create and use License Plate Numbers (LPNs) helps warehouses capture accurate inventory and maintain smooth operations. LPNs are most valuable at discrete events where a physical unit changes custody, composition, location, or status. Below are common triggers and recommended timing for LPN lifecycle actions.

1. At receipt and palletization

The most typical moment to create an LPN is at receiving when inbound goods are consolidated into a pallet, tote, or container. Once the physical unit is formed, print and apply a durable label (or capture a supplier-applied SSCC) and scan it into the WMS to link the unit to the inbound ASN or purchase order. Creating the LPN here ensures every subsequent movement references the same unique identifier.

2. During inspection and quarantine

If an inbound unit requires quality inspection, hold, or quarantine, assign an LPN so the unit can be identified and isolated without disrupting other inventory. The LPN record should carry flags for inspection status and disposition instructions.

3. When performing putaway

Scan the LPN during putaway to record the unit’s destination location. This is a core use-case: a single scan updates both the LPN’s physical location and inventory location data in the WMS, enabling accurate picking and reporting.

4. For internal transfers and replenishment

Create or scan LPNs when moving goods between zones or facilities. Whether moving a pallet to a forward pick location or replenishing reserve stock, scanning the LPN prevents location mismatches and creates an event history of movement.

5. During kitting and production

When components are combined into a kit or a produced item is palletized, assign a new LPN to the resulting unit. The new LPN should reference component LPNs in its WMS record to preserve traceability back to lots and serial numbers.

6. At picking and consolidation

Use LPNs when picking full pallets or when consolidating cases into a container for a specific order. Scanning an LPN confirms the right unit is selected and can be used for cross-dock flows or staging for shipment.

7. During packing and shipping

Before loading, scan LPNs onto the outbound shipment to validate carrier manifests and create proof of shipment. This final scan is often the trigger for invoicing, EDI shipment notices, and customer notifications.

8. For returns and reverse logistics

When returned items arrive, assign or capture an LPN so the return can be inspected, dispositioned, and routed correctly without confusion with similar retail stock.

9. For cycle counts and audits

Scanning LPNs during cycle counts speeds reconciliation; count teams can verify unit counts and locations without counting each SKU individually. If an LPN is missing or unreadable, the count process should include clear escalation steps.

10. Lifecycle events: closing and reuse

Define when an LPN is considered “closed.” Common closing events include full consumption of the unit’s inventory (all cases picked), shipment of the unit, or return-to-supplier. Decide and document whether closed LPNs can be reused, how long identifiers persist in the WMS, and how to handle historical audit trails.

When not to create an LPN

Not every object needs an LPN. Avoid creating LPNs for single items handled individually (e.g., loose consumer units picked directly to order) unless traceability demands it. Overuse can add label and process overhead with little operational benefit.

Timing best practices and practical considerations

• Minimize the time between physical unit formation and LPN creation; immediate labeling reduces the risk of misplaced or unlabeled units.
• Ensure label durability matches environmental conditions — frozen storage, wet environments, or long transit legs require stronger materials or RFID alternatives.
• Use handheld scans at each handoff to maintain a continuous event history; unattended gates and conveyors can supplement but should be validated periodically.
• Automate LPN creation where possible (WMS-generated SSCCs) to reduce manual errors and speed throughput at busy docks.

Common timing mistakes

• Delaying LPN assignment until putaway can leave units untracked in staging areas, increasing misplacements and picking errors.
• Reusing LPNs too quickly without clearing historical data can corrupt audit trails and make root-cause investigations difficult.
• Failing to scan LPNs at load time removes the insurance of a scanned proof of shipment and complicates dispute resolution with carriers or customers.

In summary, create and scan LPNs at the moments a physical unit is consolidated, moved, inspected, or shipped. Well-timed LPN events create an auditable movement history that powers accurate inventory, faster throughput, and better operational decision-making.