Warehouse & Distribution Science

1 Warehouse & Distribution SCIENCER elease for the latest version J. BARTHOLDI, III1 Steven T. HACKMANThe Supply Chain & Logistics InstituteH. Milton Stewart School of Industrial and Systems EngineeringGeorgia Institute of TechnologyAtlanta, GA 30332-0205 USAR evised August 21, 20161 Copyrightc 1998 2016 John J. BARTHOLDI, III and Steven T. HACKMAN. All rightsreserved. This material may be freely copied for educational purposes but not for resale aslong as the authors names and the copyright notice appear clearly on the copies. Why this But first..ivI Issues, equipment, processes11 Warehouse Why have a Warehouse ?.. Types of Material The fluid model of product Units of Two fundamental Storage: Dedicated versus Shared.

2 The Warehouse as a queuing Warehouse Sharing the work of Checking and Warehouse management Receiving and Stock locator Menu of The Supply Chain Execution Storage and handling Storage Pallet Bin-shelving or static Gravity flow Sortation On the lighter Layout476 Layout of a unit-load Rack or stack?.. Lane Reducing labor by dual-cycle Reducing labor by careful product Location of receiving and Aisle Layout of a carton-pick-from-pallet Layout for a forward Operating Quantities to store Choosing skus for the forward-pick Allocating space by Redirecting uneconomical Pallet Layout of a piece-pick-from-carton What is a fast-pick area?

3 Estimating How much of each sku to store in the fast-pick area?.. Minimizing labor to maintain a forward pick Two commonly-used storage Comparison with Differing costs per Minimum and maximum Reorder points and safety Which skus go into the fast-pick area?.. Selecting skus to minimize Stocking to equalize space or restocking Further comments on the Additional Storage by Accounting for safety Limits on Accounting for on-hand inventory Setup Redirecting uneconomical Multiple fast-pick Limitations of the fluid Size of the fast-pick How large should the fast-pick area be?.. How can the fast-pick area be made larger?.. On the lighter Detailed Case orientation and stack Packing Next First More on packing Other Order-picking14910 Routing to reduce The problem of pick-path Heuristic methods of generating short pick Path Product Pick-path How to take advantage of How much is optimization worth?

4 Work flow and Organizing a team of A model of work and Improvements that are Some advantages of bucket Bucket brigades in the Automation18712 Carousels, A-frames, and In-aisle cranes, AS/RS, and their On the lighter Special topics21113 Why crossdock?.. Freight Trailer Measuring Warehouse performance22514 Activity Warehouse activity ABC Statistical Doing On the lighter Performance Ratio-based Aggregate Are smaller warehouses more efficient?.. Miscellaneous26316 Warehousing around the North East Singapore, Hong Kong, Central and South In preparation275 VIII Appendices281A The Economic Order The Economic Order Safety stock and reorder Implications for the The Knapsack Problem289C The Shortest Path Problem293 List of Withmvendors andnstores the transportation plan consists ofmndirect shipments, each relatively small and likely subject to the higher,less-than-truckload There are onlym+nshipments through an intermediate aggregator,such as a Distribution center or crossdock.

5 Furthermore, each shipmentis larger and more likely to qualify for the lower, full-truckload The failure rate of many mechanical components follows a bathtub Distribution , which means demand for these parts is higher at the be-ginning and at the end of If two pipes have the same rates of flow, the narrower pipe holds lessfluid. In the same way, faster flow of inventory means less inventory inthe pipeline and so reduced inventory A product is generally handled in smaller units as it moves down thesupply chain. (Adapted from Warehouse Modernization and Lay-out Planning Guide , Department of the Navy, Naval Supply SystemsCommand, NAVSUP Publication 529, March 1985, p 8 17).. Among these 25,000 skus there is little correlation between popularityand physical volume of product Popularity among these 25,000 skus varies enormously, which presentsspecial challenges to effective An idealization of how the inventory level at a location changes over Use ofklocations to hold product under a policy of shared step function represents the space devoted to holding Under shared storage, space utilization increases with additional stor-age locations, but at a diminishing Order-picking is the most labor-intensive activity in most can be reduced by careful Simple pallet rack.

6 (Adapted from Warehouse Modernization andLayout Planning Guide , Department of the Navy, Naval Supply Sys-tems Command, NAVSUP Publication 529, March 1985, p 8 17)..40910 LIST OF Shelving, or static rack. (Adapted from Warehouse Modernizationand Layout Planning Guide , Department of the Navy, Naval SupplySystems Command, NAVSUP Publication 529, March 1985, p 8 17.) Gravity flow rack for cartons. (Adapted from Warehouse Modern-ization and Layout Planning Guide , Department of the Navy, NavalSupply Systems Command, NAVSUP Publication 529, March 1985, p8-17.).. Side views of the shelves of three styles of carton flow rack. Eachsuccessive configuration presents the product more conveniently but atthe cost of consuming more space. Configurations (b) and (c) occupymore horizontal space than (a) and configuration (c) also occupies morevertical Flow of unit-loads through a typical Pallets that require extra labor to 1-deep versus 2-deep The floor space charged to a lane includes storage space, any gap be-tween lanes, and one-half the aisle width in front of the Waste, measured as pallet position-days that are unoccupied but un-available, depends on both the lane depth and the aisle width.

7 Thefour pallets of this sku should be stored either 2-deep or else 4-deep,depending on the width of the Under single-cycle protocol, half of all forklift travel is unproductive(red lines). In this example, both receiving and shipping are at thebottom (black disk). Trips to stow a pallet in an available location (graysquares) require that the forklift return with empty forks. Similarly, anytrip to retrieve a pallet from a location (black squares) requires that thejourney begin with empty Dual-cycles can reduce dead-heading by enabling travel directly from astow to a retrieval. In this example, each of two stows (gray locations)have been paired with a retrieval (black locations). Dead-heading isshown in When receiving and shipping are separated, a dual-cycle trip must dead-head between them (dashed red line in the center).

8 The blue location (right) is more convenient than the red location (left)because the total distance from receiving to the location, and from thereto shipping is When receiving and shipping are located at opposite sides of the ware-house there are many locations of equal convenience, and with the mostconvenient on a line between shipping and receiving. (The darker lo-cations are the more convenient.).. When receiving and shipping share the same dock (at the bottom in thisexample) then there are a very few, very convenient locations as wellas some very inconvenient locations. (Darker shading indicates moreconvenient locations.)..66 LIST OF A cross-aisle allows more direct and therefore shorter travel betweenstorage Angled aisles, suggested by Gue and Meller, allow more direct travelbetween storage and a central location of receiving/shipping (at thebottom).

9 : Which is the better layout?.. : Should a cross-aisle be located close to receiving/shippingor far?.. : Critique this layout of a service parts Distribution Typical flow of cartons through a Cartons are picked from the bottom, most convenient, level; whenthe bottom location has been emptied, a restocker refills it by drop-ping a pallet from above. Newly arriving pallets are inserted into the(high) overstock. (Adapted from Warehouse Modernization and Lay-out Planning Guide , Department of the Navy, Naval Supply SystemsCommand, NAVSUP Publication 529, March 1985, p 8 17).. Cartons are picked from pallet flow rack onto a conveyor. The flow rackis replenished from behind. (Adapted from Warehouse Modernizationand Layout Planning Guide , Department of the Navy, Naval SupplySystems Command, NAVSUP Publication 529, March 1985, p 8 17).

10 Skus ranked by labor The view from above of a forward area consisting of a single aisleflanked by two rows of 1-deep pallet The view from above of a forward area consisting of a single aisleflanked by two rows of 2-deep pallet flow Typical flow of product through In the simplest case, all the skus in the fast-pick area have been Optimal allocations (dark red) have less variability in volume thanEqual Time allocations (left) and less variability in number of restocksthan Equal Space allocations (right), as this example Especially large or slow-moving skus are better picked from the reservearea. This allows the space they would otherwise occupy to be devotedto more popular The net benefit realized by storing a sku as a function of the quantitystored.