In this post I will describe the concept and the implementation of production supply via route trains[i] (aka tugger trains) in SAP S/4HANA for manufacturing logistics. You can find an overview for SAP S/4HANA for manufacturing logistics here.
I will explain the underlying master data objects and how a warehouse request item in SAP Extended Warehouse Management (EWM) will find a suitable route for the planned production supply.
The execution of such a supply process will be the content of the next post in this series.
Route trains are industrial indoor or outdoor equipment for the transport of products in a production site, for intralogistic processes like e.g. production supply to or removal of empty handling units from the production supply areas (PSA), mainly in the manufacturing industry.
Route trains consist of a towing vehicle, goods carriers attached to the towing vehicle and racks (load carriers), which are loaded onto the goods carriers. Route trains have a higher capacity than forklifts and therefore reduce traffic and increase efficiency and safety in the warehouse.
Route trains have huge benefits for production sites where the available space at the PSA is limited and the number of different produced finished goods is high (requiring a high variance of product depending e.g on the production sequence of cars).
Since release 1909 SAP Extended Warehouse Management (EWM) supports the Distribution Equipment Process which is operated by radio frequency (RF) devices.
This process is used to bring products to PSAs based on warehouse requests using standard warehouse order processing using picking via RF and loading on and unloading from a distribution equipment (technically spoken: a resource in EWM) to the PSAs.
In this concept the Handling Unit (HU) structure template was created: it defines a rack structure and is required if the picking process uses different compartments which holds the information, which product was put into which section of a rack.
This information is validated when the rack is unloaded at different PSAs: the products need to be identified by the logical position in the rack for unloading. You can validate the loading position during unloading to ensure that the product from the correct position was unloaded.
Usually a warehouse has many different rack types, each one specifically build for a group of products. On the other hand, racks can also be commercially bought, but then the number of variants is limited.
However, the EWM process does not support planning or workload distribution over multiple hours of demand of the products: all picking HUs can be loaded onto the same distribution equipment as there is no information available, which and in which sequence the PSAs shall be served in one process.
This gap is filled by the route train process in SAP S/4HANA for manufacturing logistics.
The master data
The route train process in S/4HANA for manufacturing logistics has – amongst others – its own master data “Stop”, “Route”, “User”, “Route Group”, and “Route Parameter Groups”.
These master data are maintained in SAP Fiori launchpad.
The Manage Stops app allows to maintain two different types of stops: transfer points and production supply area.
Transfer points are areas in the warehouse where the route train is handed over from e.g. a logistics service provider, which is responsible for the picking process to a second service provider, which is responsible for the unloading process. There is no unloading on transfer points; technically the driver changes.
Stops of type PSA need to be created in SAP ERP and EWM first as PSA, then they can be enriched with additional data.
When the PSA cannot be reached via the route train directly then a handover point can be defined where the HUs can be unloaded from the route train. The unloading warehouse task will then be confirmed with an exception code to the handover point..
You can maintain attributes like preferred unloading direction and confirmation method for the RF unloading process.
The Manage Routes app is the most important master data app in the route train process.
The route defines the round trip based on the sequence of the stops of a route train in the warehouse. In a real life analogy, this is the similar master data concept like a bus schedule contains planned stops and a planned departure time for each stop.
The Manage Routes app is – similar to the Manage Stops app, the Manage Route Groups app and Manage Users app- a draft enabled app based on the ABAP programming model for SAP Fiori and can be easily enhanced by customers and partners: we have provided enhancement points in the backend for the route object and the frontend can be enhanced using standard enhancement techniques.
Routes can have different versions of the sequence of stops (route version) defined by its valid from date and time. Speaking in the bus-analogy: there might be different schedules for weekdays and weekends.
However, at a given point in time only one single route version can be active.
You can create new routes, copy existing routes or edit existing routes.
In the header section the route ID, the warehouse, the lifecycle status and a description is maintained. The General data is retrieved from the underlying route type. The route type is used to separate different route train processes like e.g.
- Route train with tactet tours and upfront planning (runs e.g. every half an hour)
- Route train with tour creation just before loading
- Loading lane strategy (this is when to find the loading lane) etc.
The start and the end point of the route define where the stock of a route train is put when a round trip starts and where the empty racks shall be posted when the round trip ends.
The route version data open a whole new area of master data settings like limitations for number of racks, resource group, requirements for a towing vehicle, loading parameter like the loading position of a rack must be entered by the operator etc.
You can maintain time data: this information is used in case you operate your route in a tacted manner and run route train e.g. every 30 minutes, while loading on average takes another 30 minutes.
Finally, you assign your relevant stops and transfer points (which have been maintained in the Manage Stops app before) to the route version: here you can overwrite the master data from the stop master data for each version so you can maintain the stop data in general, but overwrite it for a very specific route version.
You need to activate your route version: only versions in status “active” will be used for route determination.
Manage Route Groups
The Manage Route Groups app allows to group routes into freely defined groups.
You can assign route groups to users so that you can restrict the usage of a route to a specific circle of persons (see Manage Users app).
Manage Route Parameter Groups
The Manage Route Parameter Groups app is another grouping function. While you can assign a route to as many route groups as you like, you can assign a route only to one single route parameter group in the Manage Routes app.
There is currently only one parameter in this group: the cycle selection parameter. This parameter is used when the actual trip for a route train is determined: when you maintain a value n>0 then the system uses not the determined trip, but uses n trips before the actual relevant trip.
The Manage Users app is used to combine information from the aforementioned Manage Route Groups app to users.
The assignment of a user to a route group restricts this user to the execution of route train trips only for routes of this group. With this approach you can control especially for very dynamic warehouses with many different routes, which user can work for which route based on the experience and knowledge of the user.
Determination of the route: integration into EWM delivery management
Production supply to PSAs via distribution equipment can be performed using production material requests, outbound deliveries for Kanban, stock transfer, posting change and stock transfer for JIT (Just in Time). Production supply via warehouse tasks without preceding delivery document is not supported.
As SAP S/4HANA for manufacturing logistics is based on the standard EWM functionality distribution equipment, the route train process is limited to the same supply processes and is therefore based on a delivery document in EWM.
Depending on the complexity of a warehouse and its production supply processes, the number of routes and their change frequency can increase dramatically. While a small and rather simple warehouse can be served by e.g. 2 or 3 routes on a scheduled basis, more complex warehouses with complex processes and supply from different start storage types with hundreds of PSAs can have 10 to 100 different routes with high frequent changes of the assignment of PSAs to routes.
The route determination is implemented in the EWM delivery update before save and uses the condition technique to determine, which route shall be used to serve a specific delivery item.
Condition technique always uses a determination procedure, which contains condition types, which are determined via access sequence from condition tables. The determination procedure is assigned to document types per warehouse via customizing.
SAP S/4HANA for manufacturing logistics delivers 3 condition tables, customer can build their own custom-specific condition tables based on the field catalogue for the the application ‘ILO’.
Condition records are maintained via Maintain Condition for Route Determination app or via transaction /SAPCDN/GCM using application ‘ILO’ and usage ‘IR’.
These condition records are evaluated during the update of the delivery item.
What is the result?
Based on the condition records the system determines a value for the route, based on valid condition records at a point in time when the products shall arrive at the PSA. The system analyses each determined route, if the PSA is also part of the route version, which is valid at the demand date and time. If the PSA is not part of this specific route version, the system evaluates the next found record until a valid route is determined.
The route is stored on the level of the delivery item and can be re-evaluated when the delivery document is updated.
The planning of a production takes place in a backwards calculation: from the planned start of the assembly you can subtract the transport time and the loading time of a route train and the planned picking duration.
As now the route is determined, the route specific transport and loading time can be used to calculate the latest point in time when the picking must be finished. Considering now the picking duration, which can be maintained in an own app Maintain Picking Duration, the system can determine the picking start time.
This picking start time can be used to determine a picking wave. This wave assigns different warehouse request items into one wave; releasing this wave will then create the warehouse order and warehouse tasks for picking.
When now hundreds or thousands of warehouse requests with slightly different demand dates and times are created in EWM, then they are assigned to routes (depending on condition records) and the planned pick start time is stored on the warehouse request item. These items can then be put into picking waves using wave options and wave capacities so that each wave then can represent a trip of the route (we call this object “Tour”) and is bundled for picking, loading and unloading using the route information on warehouse order, warehouse task and handling unit.
In the next post of this series I will explain some details on the execution part of the route train process: the tour.
I will explain the tour object and tour creation concepts. I will describe the loading and unloading process of tours and the possibilities to monitor tour execution
All pictures and screen shots are taken from SAP internal systems. They contain only mocked data and not real world examples.