The Warehouse Design and Control Problem

1. The Warehouse Design and Control Problem Based on Rouwenhorst et. al.,EJOR, Vol. 122, pgs 515-533, 2000 Yoon, C. S. and Sharp, G., IIE Trans., Vol. 28, pgs 379-389, 1996

3. Topics already covered (cont.)

4. Topics already covered (cont.) Major warehouse equipment, its functionality, and justification Containers & Unitizing Equipment Storage and Retrieval Equipment Unit Load Small Load Conveyors Warehouse docks and dock-related equipment Automatic Identification and Communication Equipment

5. Major decisions underlying the Warehouse deployment and operations Configuration issues Organization of the material flow Unit Loads Establishment of a forward area items to be included in the forward area sizing of the forward area Zoning, Time Windows and Pick Waves Equipment selection and its sizing storage modes order picking and material handling equipment Warehouse management system and automatic identification and communication equipment Layout: Allocation of Storage Capacity Personnel skills and sizing

6. Major decisions underlying the Warehouse deployment and operations Policies Receiving policies Assigning trucks to docks Storage policies Assigning received material to storage locations Replenishment policies Order processing policies order batching policies zoning policies picker routing Sortation and consolidation policies Shipping policies

7. Decision / Performance Criteria

8. Warehouse types/missions and Competitive Strategies Factory warehouse: Interfaces production with wholesalers small number of large orders daily advance info about order composition => focus on cost and order accuracy (responsiveness depends heavily on production schedules) Retail Distribution warehouse: Serves a number of captive retail units advance info about order composition carton and item picking from a forward area more orders per shift than consolidation/shipping lanes => focus on cost, accuracy and fill rate (responsiveness depends heavily on truck routing schedules) Remark: If the retail units are not captive, then responsiveness becomes a crucial issue!

9. Warehouse types/missions and Competitive Strategies Catalog Retailer: A warehouse filling orders from catalog sales a large number of small (frequently single-line) orders item and, sometimes, carton picking daily composition of orders usually unknown only statistical information available => focus on cost and response time Support of Manufacturing operations: A stock room providing raw material and/or work-in-process to manufacturing operations many small orders only statistical information available about order composition stringent time requirements (e.g., response in 30 min) => focus on response time but also accuracy and cost

10. Yoon & Sharp�s design procedure

11. Defining Department and Subsystem structure

12. Determining the basic system structure

13. Warehouse Activity Profiling(c.f. Bartholdi & Hackman, Chpt. 10)

14. Addressing the problem complexity:Hierarchical Decomposition Strategic-level decisions: they have the longer-lasting impact on the operation of the warehouse, and involve major investment process flow design equipment selection Tactical-level decisions: medium-term decisions which might still involve significant investment sizing of the facility areas and its equipment Storage layout resolution of organizational issues like the storage and replenishment schemes, and batch sizing Operational-level decisions: Decisions and policies related to the real-time operation of the facility assignment and control problems of people and equipment

15. Strategic-Level Concerns (Rouwenhorst et.al.)

16. Tactical-level concerns(Rouwenhorst et. al.)

17. Operational-level concerns(Rouwenhorst et. al.)

18. General Remarks The decomposition is ad-hoc: no theoretical justification Top-down approach: Higher-level decisions constitute constraints for lower-level decision making: However, they must be revised if the lower-level problems become infeasible Most existing quantitative analysis addresses tactical and operational issues Strategic level issues hard to formally model and analyze due to underlying problem complexity elusive / intangible nature of some of the considered criteria (e.g., flexibility). Typically, one seeks to narrow down the design alternatives to a few configurations that tend to minimize (annualized investment and operational) costs, while meeting some technical and performance-related constraints

19. Course roadmap Familiarize ourselves with the formal theory and key analytical results addressing some of the problems identified in the above taxonomy. Storage configuration and storage policies the forward/reserve problem order-picking: batching, zoning, and routing Warehouse layout Configuring and controlling automated storage and retrieval equipment Cross-docking Address the synthesis/design problem through project assignments Rouwenhorst et. al.: a good starting point for tracing literature on a particular problem.