Brief Introduction about Warehouse Management

Warehouse Management:

                A warehouse management system (WMS) is a key part of the supply chain and primarily aims to control the movement and storage of materials within a warehouse and process the associated transactions, including shipping, receiving, putaway and picking. The systems also direct and optimize stock putaway based on real-time information about the status of bin utilization. A WMS monitors the progress of products through the warehouse. It involves the physical warehouse infrastructure, tracking systems, and communication between product stations.

            More precisely, warehouse management involves the receipt, storage and movement of goods, (normally finished goods), to intermediate storage locations or to a final customer. In the multi-echelon model for distribution, there may be multiple levels of warehouses. This includes a central warehouse, a regional warehouses (serviced by the central warehouse) and potentially retail warehouses (serviced by the regional warehouses).

A typical Process flow could be like:

1. Creat GR
2. Create TR for putaway
3. Create TO
4. Confirm
5. Create Outbound Delivery
6. Create TR for this delivery
7. Create TO
8. Confirm TO.

Warehouse Management Table Process flow in SAP (WM) :

Transfer requirement
LTBK -  Transfer requirement - header
LTBP -  Transfer requirement - item

Transfer order
LTAK -  Transfer order - header
LTAP -  Transfer order - item
Master data - stock positions
LQUA -  Quants

Inventory documents in WM
LINK -  Inventory document header
LINP -  Inventory document item
LINV -  Inventory data per quant

The easiest way to determine all WM tables is via the data dictionary.
Transaction SE11
Press F4 in field tables.
On the popup for the table search, enter LVS in field development class and execute

Some of the mostly used tables for WM:

Inventory document
IKPF  -  Header: Physical Inventory Document
ISEG  -  Physical Inventory Document Items
LINK  -  Inventory document header in WM
LINP  -  Inventory document item in WM
LINV  -  Inventory data per quant

Storage locations and stocks
LAGP      -  Storage bins
LEIN        -  Storage unit header records
LQUA      -  Quants
LQUAB    - Total quant counts for certain strategies
MEIK      -  Make-to-Order Stock for Customer Order
MSCA    -  Sales Orders on Hand with Vendor
MSKA    -  Sales Order Stock
MBPR    -  Stock at Production Storage Bin
MLGN    -  Material Data per Warehouse Number
MLGT      -  Material Data per Storage Type

Some more tables:

T300T - Warehouse Number Descriptions

T301  -  WM Storage Types

T301T  -  WM Storage Types Descriptions

T320  - Assignment IM Storage Location to WM Warehouse Number

T331  - Storage Type Control

T333  -  WM Movement Types

Transaction Codes for WM

Warehouse

LL01 - Warehouse Activity Monitor

Rough Workload Estimate

VLLG - General overview
VLLE - Goods Receipt / Putaway
VLLA - Picking/Goods Issue
VLLR - Customer/Store Returns
VLLQ - Returns to Vendor

Storage Bin

LS04 - Empty Bins
LX01 - List of Empty Storage Bins
LX03 - Bin Status Report
LX04 - Capacity Load Utilization
LX29 - List of Fixed Storage Bins

Stock

LS25 - Per Storage Bin
LS27 - Per Storage Unit
LX02 - For All Materials
LS24 - Per Material - Bin-Related
LS26 - Per Material - Aggregated
MMBE - Total Stock per Material (Inventory Management)
LX27 - SLED Control List

Hazardous Material

LX24 - List
LX06 - Fire Department Inventory List
LX07 - Check Goods Storage
LX08 - Hazardous Substance List
LS27 - Per Storage Unit
LX02 - For All Materials
LX27 - Shelf Life Expiration Date - Control List
LS24 - In Bins - Material-Specific
LS26 - Aggregated - Material-Specific

Transfer Requirement

LX09 - Document Overview
LX33 - Display From Archive

Production Supply

LPIN - Material Situation WM-PP
LS41 - List of Control Cycles
LX40 - Material Stock at Production Storage Bin
LX41 - Storage Bin Selection
LX42 - Analysis of Production Orders

Some more Transactions

LB10 - Display Transfer Requirements List for a Storage Type

LB11 - Display List for Material of Transfer Requirement & Create Transfer Order

LB13 - Display Transfer Requirement

LP11 - WM Staging of Crate Parts - Instructor Demonstration Only

LP12 - Material Staging of Release Order Parts

LT04 - Create Transfer Order From TR

LT10 - Transfer Materials Received from Production to a Storage Bin

LT23 - List of Resident Documents for a Transfer Order

LT31 - Print a Transfer Order

LX09 - Overview of all Transfer Requirements

LT06 - Create Transfer Order for Material Document

LM06 - Pick a Material for Delivery

LT10 - Create a One Step Transfer Order

LT21 - Display Transfer Order

LP21 - Replenishment for Fixed Bins in WM

Some of SAP WM Functional modules:

Some more FM’s:

  L_TO_CREATE_MULTIPLE                      -Create a transfer order with two or more items

  L_TO_CREATE_MOVE_SU                      -  Create a transfer order to move a storage unit

  L_TO_CREATE_MOVE_LSR                  -  Initiate a stock transfer of storage units from an external system

  L_TO_CREATE_TR                                  -  Create a transfer order for a transfer requirement

  L_TO_CONFIRM_SU                                -  Confirm a transfer order for a storage unit

  L_TO_CANCEL_SU                                  - Cancel a transfer order for a storage unit

  L_REF_CREATE                                        -  Create transfer orders using multiple processing

  L_TO_CREATE_2_STEP_PICKING      -  Create transfer orders for 2-step picking

  L_TO_CREATE_POSTING_CHANGE    -  Create transfer orders for posting changes

  BAPI_GOODSMVT_CREATE                    -  Creation of the material document

  L_INV_COUNT_EXT                                  -  Inventory Count

WM module of SAP R/3 provides flexible, efficient, automated support that enables you to:

• manage complex warehouse structures
• define and manage storage areas and storage bins in the warehouse
• manage several different types of storage, such as high rack storage, block storage or fixed bin storage
• process all relevant postings and transactions such as goods receipts, goods issues and general stock transfers.
• monitor stock movements
• execute stock placements and removals using different put-away and picking strategies
• process stock differences
• manage hazardous materials
• use bar code scanners
• interface to external non-SAP warehousing systems
• manage inventory at the storage bin level
• ensure that stock posted in the Inventory Management system is the same as the stock in the warehouse
• integrate with materials management, product planning, quality management and sales and distribution

Advantages:

• Track exact stock location within one storage location with FIFO.
• Provides put away functionality for palletizing. etc
• Provides better picking functionality .
• Allows for picking locations with replenishment when falls below a defined quantity.
• Allows segregation of stock types within a warehouse.
  

Disadvantages: 

• Increased master data maintenance.
• Additional process step for receipt and picking.
• Requires expert knowledge to configure for maximum benefit.
• More complex to resolve problems caused by incorrect processing.
  

Generally WM provide better automation of processes, particularly with RF, but requires more maintain and process discipline. 

It is recommended that you used WM only if the standard logistics functionality is insufficient for your needs.

-As per my Knowledge and work experience, I have gathered this information. I will extend this doc in future.

Thanks

Srikanth