What is Lean Warehouse Management in SAP

                                       Lean warehouse management is the process of developing warehouse operations in such a way as to bring resource consumption to a minimum without sacrificing productivity. In other words, lean warehouse management aims to ensure your team never uses more resources than they need to when completing a specific task.

Warehouse Management with Lean WM

 When we implement the Warehouse Management System (WMS), we manage goods movements and stock changes in the warehouse at storage bin level. 

 However, if we implement Lean WM , inventory management takes place solely at storage location level. The system does not update the stock data at storage bin level using the quants.

 We use Lean WM solely for processing goods receipts and goods issues. Using Lean WM, we process the warehouse movements in basically the same way as if using the Warehouse Management System: we work with deliveries, and we create transfer orders for these deliveries. These transfer orders serve as pick lists.

 We recommend that we implement Lean WM if we wish to pick deliveries in a warehouse that we are not managing using WMS.

The use of transfer orders in Lean WM provides the following advantages:

• We can reprint transfer orders at any time.

• We can split transfer orders and thus distribute the workload better among the staff in the warehouse.

• We can pass on the transfer order target data and the names of those who process transfer orders to the HR application component, where this data can be used to calculate incentive wage.

If we do no wish to update stocks in our fixed bin warehouse at storage bin level, Lean WM provides we with the option of using the advantages of warehouse management through transfer orders in the same way as warehouse management using the WMS.

Note

 If we are already using the standard WM system, we recommend that we implement Lean WM in a further warehouse where no updating of stocks at storage bin level is necessary. In this way, we ensure that the processes for warehouse management are uniform in all warehouses.

 Since Lean WM does not update stocks at storage bin level, we can display the stock quantities solely in Inventory Management (IM) and not with the stock overview function in WM. Also, we cannot process possible stock differences that occur in the warehouse using Lean WM, only using Inventory Management (MM-IM):

Prerequisites

We can only implement Lean WM in a fixed bin warehouse; random storage is not possible.

Before we can implement Lean WM, we need to make the following configuration changes in Customizing:

1. Assign a (newly defined) storage location to a warehouse number.

2. Set up at least two storage types:

 a picking storage type as the source storage type

 A shipping area as the destination storage type for deliveries

Replenishment in SAP Warehouse Management

 Replenishment in WM

 

Source: https://wiki.scn.sap.com/wiki/display/ERPSCM/Replenishment+in+WM

Purpose

Consider the following example to understand the concept and need of replenishment.
Example : There is a rack with three compartments (Upper, middle and lower)

When the stock is manually picked by a worker in warehouse, it is always easier to pick it from the lower compartment than picking it from the middle or the upper compartment.

Now consider a scenario that the stock at the lowest compartment is consumed. And there is a new pick request for the stock. The person who would carry the stock now needs to take extra efforts to access the stock at the higher compartments. If this continues then it will be tedious and time consuming.

This is where the replenishment is important.

Whenever the stock in the lower compartment is minimum, we fill the compartment with the stock from middle/upper compartments.

Necessary Customization

The replenishment is configured by the following steps:

1. At material master, go to Warehouse management view 2 and under 'Storage bin stock', maintain the fields fixed bin, maximum quantity, minimum quantity and replenishment quantity.
   
   
   
   
   Minimum quantity - This the basis to trigger the replenishment. The replenishment is possible only when the current stock in the bin is less than this minimum quantity.
   where current stock in a bin = available quantity + pick quantity + putaway quantity (These values are taken from LQUA table)
   Maximum quantity - This is the quantity upto which the bin is to be filled or replenished.
   Note : As per the standard design, it is mandatory to maintain the positive value for the maximum quantity.
   Replenishment quantity - The bin is replenished with the multiples of this quantity.

2.     Under the path SPRO -> Logistics Execution --> Warehouse Management --> Activities -->Transfers --> Define movement types, use movement type 319 for replenishment.

3. Under SPRO -->Logistics Execution --> Warehouse Management --> Activities -->Transfers --> Define stock transfers and replenishment control, assign movement type 319 against Storage type with replenishment technique 1.

3. Run transaction LP21 to create TR if the Stock < Min Quantity  (or schedule batch job on program RLLNACH1). LP21 shows the available quantity in the bin and the requested quantity. The TR can be created for this requested quantity.

Note : If you require that the replenishment TO's are created automatically after the immediate confirmation of the removal TO(such that the bin quantity is less than minimum), this would have to be handled with user exits and WM enhancements. WM enhancement MWMTO001 can be used where there is a call to function L_REP_TO_CREATE_FROM_USEREXIT.

Enhancements

The following enhancements can be used by the customers to make the other customization as per the business requirement.

Enhancement :  MWMRP001
Short text : Customer Exit for Fixed Bin Replenishment.: Delivery Item Selection

Enhancement :  MWMRP002
Short text : Customer Exit for Fixed Bin Replenishment: TR Quantity Distribution

Enhancement :  MWMRP003
Short text : Customer Exit for Replenishment using RLLNACH1

Case Scenario

Consider a bin which has current stock of 5 PC. At material master level, the minimum quantity is 10 PC, maximum quantity is 100 and replenishment quantity is 10.
Now current stock (5 PC) < minimum quantity (10 PC)

Now when the replenishment is carried out via LP21, the requested quantity should be 90 (multiples of replenishment quantity 10). And if the replenishment is successful then the total quantity in the bin becomes 95 PC.

In case, if the requested quantity is less than 90(expected), then there might  be picked / putaway stock for the bin which can be seen by checking open Transfer requirements in LB11 and open Transfer orders in Tcode LT24.