07 Nov

Black Friday without chaos: a wave plan with multi-order carts

On Black Friday, warehouses jam for three reasons: routes are too long, consolidation is messy, and packing loses cadence. Multi-order carts cut meters walked (one route feeds several orders) and waves synchronize work with real shipping cut-offs. Here’s a practical plan—no templates, no checklists—to apply without rebuilding your WMS.

Why multi-order stabilizes peaks

• One single route to supply 4–8 orders at once reduces walking and avoids repeated aisles.
• Consolidation is cleaner: you arrive with blocks of lines that are distributed fast (put-to-light, put wall or a well-organized table).
• The team keeps steady cadence; the stop-and-go swings that kill OTIF disappear.

 

Wave structure (how to design it in 30 minutes)

 

Define real cut-offs

• List carriers and pickup windows. Group orders by cut-off (not by round hours). That becomes the day’s “clock”.

 

Choose the wave size

• Use a simple rule: Orders per wave = packing capacity per slot × number of slots until the cut-off × safety factor 0.8.
  This prevents consolidation from overloading tables and walls.

 

Set each wave’s width

• Typical duration: 45–90 minutes depending on your layout.
• Leave 10–15 minutes between waves for quick replenishment and dispatch clearance.

 

Assign resources per slot

• Shift = picking (carts) + consolidation + packing.
• Each wave has a responsible and a defined OK to ship. Without that OK, the wave does not close.

 

Route and preparation with carts (step by step)

 

Before starting

• Move top sellers closer to dispatch.
• Ensure readable labeling and tested barcodes.
• Pre-replenish critical SKUs for wave 1.

 

During the route

• Carts with compartments/totes per order.
• “Snake” route rule with no backtracking.
• Fast confirmation (hands-free scanner or quick tablet check).

 

On arrival at consolidation

• If you have put-to-light/put wall, scan and distribute; if not, use a table with a fixed order and a batch verification before packing.
• Avoid mixing waves: each wave has its own physical area.

 

Practical capacity per cut-off (three comparable scenarios)

 

Small operation (2 tables / 40–50 orders/h total)

• Work with 60–80-order waves for the first cut-off. Keep one cart feeding the table while the other returns. Don’t open the next wave until the previous one is cleared.

 

Medium operation (4 tables / 80–100 orders/h)

• Two waves in the morning and two in the afternoon. Wave target 100–140 orders depending on average distance. Leave 15 minutes between waves for replenishment and consumable changes.

 

Large operation (8 tables / 160–200 orders/h)

• Overlapping waves with an intermediate staging area. Feed the Put Wall or consolidation tables with dedicated carts; appoint a wave lead to set pace and authorize OK to ship.
• In heavy campaigns, limit feed from the most volatile channel (e.g., marketplaces) to slots per wave to avoid overflow.

 

The point is not the formula but the criterion: size waves by what packing can digest before the cut-off and protect a small buffer for contingencies.

 

Coordination with transportation, customer service and IT (what prevents fires)

 

Commercial promise aligned to cut-offs

• Make sure the website and customer service promise what the warehouse can deliver per cut-off and carrier. If marketing opens “same-day” without space in the wave, you’ll create an artificial peak.

 

Slots with carriers and real-time comms

• Agree extra pickups or flexible times during peak week and publish actual carrier arrival times on the internal board to prioritize the last half hour.

 

Change freeze and plan B

• Avoid WMS/ERP deployments during campaign week. Duplicate printers and consumables; have an alternate label layout if a line goes down. A simple plan B beats any template.

 

Common mistakes (and how to avoid them)

 

Over-inflated waves

• If you load more orders than packing can swallow, picking piles up. Size by finite packing capacity, not by team enthusiasm.

 

Unstructured consolidation

• When carts arrive mixed and the table lacks rules, rework increases. One order = one slot (wall/table), with confirmation on deposit.

 

Badly timed replenishment

• Replenishing during the wave breaks cadence. Schedule replenishment windows between waves. Undefined KPIs
• Measure daily with the same formulas (LPH, OPH, Order-to-Ship, OTIF per cut-off, and picking-error returns). If you change definitions, you won’t know if you improved.

 

Metrics to validate the plan

Before: take a typical week and calculate LPH, OPH, Order-to-Ship P50/P90, OTIF per cut-off, and warehouse-error returns.
During BF: capture the same metrics per wave.
After: compare before/after and, if it works, standardize waves for future campaigns.

 

Conclusion

Campaigns shouldn’t be “crisis mode”. With multi-order carts you reduce meters per order; with waves you align output to real cut-offs. Add orderly consolidation, coordination with carriers/customer service and consistent KPIs, and Black Friday becomes a predictable, profitable peak—not a lottery.

Want this plan tailored to your layout and cut-offs? Contact us and we’ll deliver a personalized schedule (waves, resources per slot, and consolidation rules) ready to run.