Summarizing our current results with respect to the warehouse design and control problem Based on: Yoon, C. S. and Sharp, G., “A structured procedure for analysis and design of order pick systems”, IIE Trans., Vol. 28, pgs , 1996

The warehouse processes and the underlying material flow ReceivingShipping Reserve Storage and Pallet Picking Case Picking Broken Case Picking Accumulation, Sortation & Packing Cross-docking Direct putaway to reserve Direct putaway to primary Replenishment

…or in Yoon and Sharp’s representation... RECEIVING PALLET RESERVE CASE PICK ITEM PICK SORTING A SORTING B UNITIZING SHIPPING pallets cases overpacks mul (items totes) cases (items cases) pallets cases totes (cases) items (items cases) totes (items cases) totes cases overpacks totes cases overpacks mul pallets Breakdown function Consolidation Function

Defining Department and Subsystem structure Department A Department B Subsystem A1 Subsystem A2 Subsystem An Subsystem B1 Subsystem B2 Subsystem Bn Transport Equipment 1 Transport Equipment 2 Transport Equipment k Storage structure (e.g., Gravity Flow Rack) Transfer Device Storage Equipment Retrieval Equipment (e.g., pick to light) Transfer Device Transport Equipment (e.g., forklift) Transport Equipment (e.g., Belt Conveyor)

Yoon & Sharp’s design procedure MANAGERIAL CONSIDERATIONS PRODUCT DATAORDER DATA DATA ANALYSIS SPECIFICATION OF ORDER PICK SYSTEM STRUCTURE SPECIFICATION OF EQUIPMENT SPECIFICATION OP. STRATEGIES MATERIAL FLOW INFORMATION FLOW SUBSYSTEM I SUBSYSTEM II SUBSYSTEM N SUBSYSTEM RECONCILIATION EVALUATION & SELECTION OVERALL PERFORMANCE ANALYSIS INPUT STAGE SELECTION STAGE EVALUATION STAGE

Determining the basic system structure Product data: Activity level requested quantities product properties vendor types Order data: number of line items number of items cubic volume shipping priorities product correlation Managerial requirements / company strategy Definition of major functional areas / departments Definition of departmental sub- systems Storage and material handling modes Operational policies storage policies replenishment policies order picking policies batching sorting zoning routing receiving & shipping policies

Topics Covered Equipment types, features and efficiencies Warehouse Activity Profiling: Product and Order data analysis Configuration of (departmental) storage: –space allocation –storage sizing –storage mode selection (pallet rack vs. floor storage) and configuration Optimal sizing and space allocation of the case-pick and item-pick areas; determination of the associated replenishment lots

Topics to be addressed next Warehouse Layout: Spatial Arrangement of the Warehouse departments Order picking policies: –Routing / sequencing –Batching –Zoning (Sub-system) Performance Evaluation Cross-docking

Determining the overall Warehouse Layout Based on: E. Frazelle, “World-Class Warehousing”, Logistics Resources International, Inc., 1996 Francis, McGinnis and White, Chpt. 2 and 3

Most Typical Warehouse Layouts (according to Frazelle) U-shaped Straight-thru Modular

U-shaped Layout ReceivingShipping Reserve Storage and Pallet Picking Case Picking Broken Case Picking Accumulation, Sortation & Packing Cross-docking Direct putaway to reserve Direct putaway to primary Replenishment

Some key advantages of the U-shaped layout Excellent utilization of dock resources since the receiving and shipping processes can share dock doors. Facilitates cross-docking since the receiving and shipping docks are adjacent to each other and may be co-mingled. Excellent lift-truck utilization since –put-away and retrieval trips are easily combined –storage locations closest to shipping and receiving docks are natural locations to house fast-moving items. => U-shaped layout/flow is the benchmark upon which all other layouts/flows should be compared.

Straight-thru Layout (Primarily for cross-docking facilities) SHIPMENT STAGING RECEIVING CHECK-IN RECEIVING SHIPPING TEMPORARY HOLDING AREA SORTING AND ASSEMBLY AREA

Modular Layout Appropriate for large-scale operations in which the individual processes are so large that they merit stand- alone and uniquely designed buildings E.g., –a rack-supported building for unit-load AS/RS; –an air-conditioned low-bay building for customizing operations such as monogramming, pricing and marking; –a low-bay shipping building equipped with high-speed sortation equipment.

Systematic Layout Planning (SLP) (R. Muther, 1961) Input Data and Activities Material Flow Activity Relationships Relationship Diagram Space Requirements Space Availability Space Relationship Diagram Modifying Considerations Practical Limitations Develop Layout Alternatives Evaluation Analysis Search Selection

Computerized Layout Generation Input: Activities, Space Requirements, Material Flows, Adjacency Requirements Output: A “block” layout Procedures: –Construction Algorithms: Iteratively, add one more activity to a partial layout until all activities have been placed. –Improvement Algorithms: Starting with a “block” layout, try to improve it, by going through a series of location exchanges for facility pairs or triplets. –Scoring model: An evaluation mechanism that assesses the efficiency of each block layout or insertion step, in the case of construction algorithms, based on the resulting material handling effort or the extent to which the layout satisfies the adjacency requirements expressed in the REL chart. Example Software: CRAFT, CORELAP, ALDEP, SPIRAL, (AUTOCAD)