Lesson 2 of 6
Waves: grouping work so it finishes on time
9 min
Listen to this lesson
A warehouse that creates picking tasks the moment each delivery arrives ends up with pickers walking the same aisles again and again, and trucks waiting for one last item. Waves group warehouse request items that should be processed together, usually because they leave on the same route or truck. SAP describes the goal as creating tasks "as early as necessary, but as late as possible."
What a wave is
A wave combines items from one or many warehouse requests. Items usually share a route, a carrier or a departure time, though that is not mandatory. Waves are most often used for outbound delivery orders, but can also group posting changes and internal stock transfers. When a wave is released, EWM creates warehouse tasks for its items and then warehouse orders from those tasks. Until release, the items wait.
- Delivery order items arriveGreat Lakes, two other fleet customers on route GL-NORTH
- Wave planningThe scheduled wave report groups items by route with template "PM routes"
- Items assigned to a waveWave for 13:00 release, completion 15:30
- Simulate release (optional)Supervisor checks the expected workload
- ReleaseTasks created, then warehouse orders built by creation rules
- ExecutionPickers receive orders through their queues
Wave templates
A wave template is EWM master data that defines how waves of a certain kind behave. SAP lists these parts:
| Template part | What it controls | Contoso "PM routes" template |
|---|---|---|
| Release method | Automatic (at a set time), immediate, or manual | Automatic at 13:00 |
| Wave type | Allows specific monitoring in the warehouse monitor | OUT-ROUTE |
| Wave category | Can be used as a filter in warehouse order creation rules | PM |
| Dates and times | Start, release and completion times of the wave | Release 13:00, completion 15:30 for a 16:00 departure |
| Capacity profile | Capacity limits for the wave | Maximum 400 picking items |
| Calendar | Workdays | Detroit plant calendar, Monday to Friday |
Parts of a wave template.
EWM finds the template with the condition technique, using fields from the warehouse request header or item such as route or ship-to. It compares each item's planned completion time with the template's wave options and picks the one whose completion is not later than the item needs. Automatic wave assignment is switched on in the warehouse process type. Alternatives exist: waves can be created manually in the wave maintenance transaction (/SCWM/WAVE in most systems), by a background report with variants, or with reference to a transportation unit so everything for one truck travels together.
Working with waves
- Simulate release shows the workload before committing; if work is needed now, release directly from the simulation.
- Release creates tasks and warehouse orders.
- Lock and unlock stop and resume further processing.
- Merge combines waves, for example when two routes are consolidated on one truck.
- Delete removes all items from the wave, which then wait for a new assignment.
- 08:00Morning items assignedOrders received overnight go to the 10:00 wave
- 10:00AM wave releasedPickers work local routes; trucks leave 12:00
- 12:30Cut-off for PM routesNew items after this time go to tomorrow's first wave
- 13:00PM wave released automaticallyGreat Lakes and route GL-NORTH items picked
- 15:30Wave completion targetAll items staged at doors DR04–DR06
- 16:00Trucks departGoods issue posted at departure
What would you do?
An urgent order for Great Lakes Fleet Services arrives at 13:20, after the PM wave was released. The customer needs it on today's 16:00 truck. What is the best approach?
- Waves group warehouse request items so work is created as late as possible but in time for departure.
- Wave templates define release method, type, category, times, capacity profile and calendar.
- Templates are found with the condition technique; automatic assignment is set in the warehouse process type.
- Release creates tasks and warehouse orders; simulate first when time is tight.
Check your understanding · not graded
Lesson check
1. What happens when a wave is released?
2. Which release methods can a wave template use?
3. How does EWM choose a wave template for an item?
4. Why simulate a wave release first?