Combining Items in Waves

Waves are groupings of warehouse request items (that is typically, the items of outbound delivery orders) that control warehouse activities, like picking. These groupings are then processed together in subsequent processes, for example, the transfer of all warehouse request items assigned to a wave to warehouse task creation.

The most important task and usage of a wave is the automatic creation of warehouse tasks at the scheduled time. While the creation of warehouse tasks for inbound deliveries is most probably triggered through the physical arrival of the product (and the goods receipt posting), you might have outbound delivery orders that are due at any time in the next hours, days, or weeks. Wave management helps you to combine the items that are planned are to be picked at the same time, or for the same process, and is therefore very important for the automation and optimization of your warehouse.

SAP Extended Warehouse Management can combine warehouse request items and split items into waves based on criteria such as activity area, route, or product. You can create waves manually or automatically using wave templates. If you want to create a wave manually, on the EWM Index screen, choose Extended Warehouse Management → Work Scheduling → Wave Management → /SCWM/WAVE Maintain Waves, and then choose Create. SAP EWM creates an empty wave. You enter the remaining information manually such as the assignment of warehouse request items.

You can automate the assignment of warehouse request items to waves. SAP EWM uses the condition technique to determine which wave templates correspond to certain data from the header, item, or split item of a warehouse request.

For automatic wave assignment, the following prerequisites apply:

• You have created wave templates.

• You have defined the conditions for wave template determination.

• You have created condition records that connect the conditions and wave templates.

• You have set the Automatic Wave Creation indicator for the warehouse process type that is found for the warehouse request item.

  Note

  It is also possible to create waves:

  • For a transportation unit. Either manually in the shipping cockpit, or automatically using the report /SCWM/R_TUDLV_AUTOPLAN_TU.
  • Using the report /SCWM/R_WAVE_PLAN_BACKGROUND.

  In these cases, the creation is not triggered through the warehouse process type.

  It is also possible in the transaction Maintain Waves (/SCWM/WAVE) (where you create waves manually) to select items which are not assigned to a wave, and to choose Assign Automatically. Then EWM automatically assigns the chosen warehouse request items to waves, using the same logic as for the automatic wave assignment.

A wave template is a schema that defines the attributes of all the waves that are based on it. It serves as the infrastructure for automatic wave assignment. Wave templates enable the same wave attributes to be reused for different warehouse request items that comply with the same conditions. You can also use wave templates to create waves manually, or, in the case of automatic wave assignment, to assign items or split items from the warehouse requests to existing waves that are based on the wave templates.

The following attributes are available for wave templates:

• Release method (with the possible values Automatic, Immediate, and Manual)

• Wave type (enables specific monitoring in the Warehouse Management Monitor)

• Wave category (you can use as a filter for warehouse order creation rules)

• Wave assignment is also possible after wave release indicator (you can use it to assign additional warehouse request items to a wave that has already been released)

• Control for bin denial

  This allows you to choose between the following options:

  • You can leave an item in a wave, or, in other words, release it again later.
  • You can remove an item from a wave, or, in other words, reassign the item.
  • You can have the system immediately create a warehouse task with an alternative source bin.
• Wave Release Retry Interval

  If you set a retry interval for a wave template, the system automatically schedules a new wave release job when a wave using the template can not create all warehouse tasks due to missing stock. You can specify the retry interval in minutes for when the system should schedule the new wave release job. If there is no retry interval, the system does not create a new wave release job.

• Settings for two-step picking

  Settings for two-step picking (which is explained in more detail later) can be define wave template specific.

A wave template may consist of one or more wave template options.

The following attributes are available for wave template options:

• Data for date and time

  This includes the following:

  • Cutoff time: the time up to which you can add items to the wave

  • Release time: the time by which the wave must be released. This is used for the automatic wave release job.

  • Pick start and pick completion, pack start and pack completion, staging completion and wave completion

• Calender for defining workdays

• Staging area group and Staging area for the resulting warehouse tasks (WTs)

• Indicator for special activity

  You can use this indicator to change the activity category that is defined by the warehouse request. All WTs created when the wave is released receive the new activity (and thus the corresponding activity area and pick path).

• Mode that applies to all WTs created when the wave is released

  A mode is a state that determines the following:

  • Weighting factors used for warehouse order prioritization
  • Time intervals and units of measure for rounding latest starting dates (LSDs)

• Capacity profile for defining capacity limits

You can process waves and control your warehouse activities in the following ways:

• Lock or unlock

  You can lock a wave with the status I (initial). The status of the wave becomes H (locked). When you unlock a wave, EWM resets the status of the wave to I. You cannot release locked waves automatically.

• Merge

  You can merge as many waves as you want. The prerequisites are as follows:

  • The waves have not yet been released, in other words, they have the status I (initial, wave is created) or H (hold, wave is locked).
  • All the waves have the same status, either I, or H.
  When you merge waves, EWM assigns all the warehouse request items for the selected waves to the wave with the lowest wave document number.

• Release

  Waves are used to create warehouse tasks and warehouse orders. They can be released in the following ways:

  • Automatically:

    EWM creates a job that automatically releases waves on the release day and at the release time.

  • Immediately:

    The wave is immediately released after it's creation.

  • Manually:

    You can manually release a wave at any point in time in the monitor or in wave processing. When you manually release waves, you can also release "waves locked". In this case, EWM sets the status Locked for the warehouse orders created. As a result, these warehouse orders are locked for further processing for the time being.

    You can release waves multiple times. For example, if you release a wave, but EWM can only generate some of the required warehouse tasks since there is not enough stock, you can release the wave again at a later point in time. You can display the log by using the Release Log button. To do so, on the EWM Index screen, choose Extended Warehouse Management → Work Scheduling → Wave Management → Maintain Waves.

  • Subsystem:

    You can release a wave for a downstream subsystem. As a result, EWM transfers the warehouse orders to the downstream subsystem.

• Assign or remove assignment

  You can assign warehouse request items to a wave or remove the assignment. Here, the lock time for the wave must not have expired yet. Moreover, the wave must not have been released yet. If you have set the Wave Assignment Also Possible After Wave Release indicator as an attribute in the wave template, you can, however, assign an additional warehouse request item to waves that have already been released.

• Split

  You can select a warehouse request item and remove it from the current wave. EWM creates a copy of the wave and assigns the warehouse request item to the copy.

• Delete

  When EWM deletes a wave, it removes the assignment of all the warehouse request items to the wave. EWM deletes a wave completely; in other words, you can no longer archive it.

• Wave Release Simulation

  You can simulate the release of one or more selected waves. The simulation can be triggered in the Warehouse Management Monitor using the methods Simulate Waves and Simulate Single Waves or with the report /SCWM/R_WAVE_SIMULATE. After the wave release has been simulated, you can perform other actions, such as viewing warehouse order creation information or the wave release simulation log by choosing the Display Log button on the Wave Simulation: Results screen. You can also manually release waves from this screen.

In the description of the automatic assignment of items to a wave, a split item is mentioned. A split item can be created when the flag Rough Bin Determination is set in the warehouse process type. When the strategy Large / Small Quantities is used, different packaging sizes are picked from different storage types. When the required quantity of the warehouse request item can not be fulfilled by one packaging size, it means that the rough bin determination finds separate storage types for the different packing sizes.

In the example above, in rough bin determination, EWM assigns warehouse request item 10 with a quantity of 111 of product A to three different storage types for picking in accordance with the quantity-dependent picking strategy. One piece is assigned to storage type KB1, 10 pieces are assigned to storage type KB2, and 100 pieces are assigned to storage type KB3. As the picking duration for these different quantities is probably not the same, it makes sense to determine waves by using the source information. In this case, you would usually use the activity area for the picking activity as part of the condition record for the wave determination.