Kanban in the Heijunka Process 
Use
You can use kanban in the heijunka process to control and monitor the production of materials. Production smoothing is supported and even production over a certain period ensured through the ongoing production of small quantities on the basis of the kanbans.
Kanban processing is a means of lot-size creation. The quantity produced using kanbans should be defined in such a way that the lots are of a size suitable for the smoothing process.
Production is triggered by setting a kanban container to "Empty". A planned order is then generated for the quantity needed. To ensure stable planning for the heijunka process, you can specify that a planned order generated in MRP that is already intergrated in the sequence schedule is to be used for an empty kanban.
Prerequisites
You have chosen a replenishment strategy with in-house production and the control type Processing with Planned Order/MRP or Processing with Planned Orders and Cost Collector in Customizing for Kanban (see also PP Kanban Replenishment Using Run Schedule Quantities ).
Features
Assignment of MRP Planned Orders to Kanbans
Normally, when the status of a kanban changes from "Full" to "Empty", either a new planned order is created or an existing one from the MRP run reduced. If you are using sequencing and have already created a sequence for the planned orders, the generation of a new planned order through kanban may have an effect on the planning that has already taken place because the sequence of the existing planned orders changes.
To prevent a new planned order from being created (thus changing the existing planning situation) when a kanban is set to "Empty", you can specify that a planned order created in MRP is to be used for the empty kanban.
You make the settings for this in Customizing for replenishment strategies for in-house production. The assignment of MRP planned orders to kanbans is possible for the control types Processing with Planned Orders/Preplanning in MRP or Processing with Planned Orders and Cost Collector only .
In the control type, you can specify the following system behavior via the Use of Production Plan indicator:
The system is to use planned orders with the same production version only.
The system is to use planned orders with the same production version and planned orders without a production version only.
The system is to use all planned orders.
In addition, in the usage horizon you specify the workdays within which an existing planned order can be assigned to an empty kanban container.
Fixed Lot Size
For the system to be able to used a planned order for a kanban, the quantity of the planned order must be the same as the kanban quantity. You can ensure this by specifying a fixed lot size in the material master record, for example.
Lead Time Scheduling
If the system fails to find a suitable planned order, it generates a new one for which the lead time scheduling process is carried out to determine the production date.
Order Data on the Kanban Board
You can display the order data for a material and also the scheduling of the orders with the sequencing on the kanban board:
Assigned orders
The list shows all orders assigned to the kanban containers of the selected control cycle.
Non-assigned orders
The list shows all orders that have been created for a material but which are not used for Kanban. This list serves as a preview of the future planned production of the material.
All scheduled orders
The list shows all assigned orders of all control cycles sorted by their production dates.
Kanban Data on the Sequence Planning Board
You can display the kanban information for a planned order that is assigned to a kanban on the sequence planning board.
To do so, show the order list on the sequence planning board. Here you can display the following kanban information:
Control cycle
Production supply area
Identification number
Kanban status