Outline

1. Outline • small item storage and retrieval system • picking operations • case study

2. Small Item Storage and Retrieval Systems

3. Picker-to-Stock Systems: Storage • bin shelving • modular storage • gravity flow rack • space saving system

4. Bin Shelving • oldest method • advantages • simple • low initial cost • variable bin content over time

5. Bin Shelving • disadvantages • under utilization of space inside bins • limited vertical space of columns of bins • ill positioned picking height • more space • expensive • difficult for personnel supervision • security problem

6. Modular Storage Drawer/Cabinets • a cabinet holds drawers with modular storage compartments • especially suitable for sets of components (put in compartments of the same drawer) • save space • more human factors in storage and retrieval

7. Gravity Flow Rack • SKUs fairly similar in shapes and size • inclined rack, high at end • loaded at back and unloaded in front • back-end goods pulled to front by gravitational force • FIFO • usually for fast moving goods

8. Space Saving Systems • mezzanines • high floor height • use mezzanines for secondary storage • mobile storage unit

9. Picker-to-Stock Systems: Retrieval • cart picking • tote picking • man-up system • robotic item picking

10. Cart Picking • equipped with different peripherals • paperwork station • marking equipment • ladder • bar-code accessories: scanner, reader, data terminal • automatic location directions • light guiding system • RF links • compartments for sorting batch orders

11. Tote Picking • picked items to totes • totes on conveyors for pickers to carry or push them around • compartments on totes for multiple orders

12. Man-up Systems • man aboard an AS/RS system for picking • full usage of height (e.g., 40 ft) in storage • generally pick multiple orders • important for slotting of storage area and sequencing of picks

13. Robotic Item Picking

14. Stock-to-Picker Systems • carousel • horizontal • vertical • miniload

15. Horizontal Carousel • limited height • a picker on multiple carousel

16. VerticalCarousel • shorter pick time than horizontal carousel • better picking position • better item protection

17. Miniload Automated Storage and Retrieval System • low floor space requirement • manual or automatic storage and retrieval direction • greater maintenance requirements

18. Automated Item Dispensing Machines • automated vending machine with conveyor or pneumatic system to send selected items to the collection point

19. Bin Shelving Flow Racks Storage Drawers Horiz. Carousel Vertical Carousel Miniload AS/RS Auto. Disp. Summary Characteristics of Alternative Broken Case Picking Systems Gross Cost Net Cost Floor Space Reqt. Human Factors Mainten-ance Item Security Flexibility Pick Rate

20. Summary Characteristics of Alternative Broken Case Picking Systems Bin Shelving Flow Racks Storage Drawers Horiz. Carousel Vertical Carousel Miniload AS/RS Auto. Disp. Gross Cost Net Cost Floor Space Reqt. Human Factors Mainten-ance Item Security Flexibility Pick Rate

21. Chapter 8 Picking Operations

22. items Qty lines of items volume and weight of items in lines Picking Operations • expensive: order picking (50%); shipping (15%); receiving (15%); storage (20%) • nature of items setting constraints on batching or zoning of orders

23. Typical Distribution of an Order Picker’s Working Time 55% 20% 15% 10% Traveling Searching Extracting Other

24. do not change (much) with schemes of picking orders sequencing orders; un-grouping, grouping and regrouping lines change with schemes of picking orders Schemes of Picking Orders documentation, reaching, searching, extracting, counting, restocking traveling distance and sorting effort What is the best mode to pick in a given situation?

25. Schemes of Picking Picking Schemes Freeform Picking Zone Picking Single Order Picking Progressive Assembly Downstream Sortation Batch Picking Manual Sortation Split Single Order Picking Automated Sortation Complete Single Order Picking

26. Single-Order Picking • good for • order integrity • “large” orders or emergency orders • long traveling distance for a few items • high distance traveled per line

27. Batch Picking • picking multiple orders in a trip to reduce distance traveled per line • need to sort item • several compartments (in a pick cart) to differentiate lines of different orders • group items and quantities during picking and sort later

28. Zone Picking • a dedicated, non-overlapping zone to each picker • pros • reduced travel distance • familiarization of locations and products • minimal congestion • clear accountability • minimal socialization • cons • extra effort in order assembly • workload imbalance

29. zone 1 zone 2 zone 3 zone 1 zone 2 zone 3 sort-ing Methods to Assemble Orders • progressive order assemble • downstream sortation

30. Improvement of Picking Operations • issue pack optimization • pick from storage • pick task simplification • order batching • slotting optimization • pick sequencing

31. Issue Pack Optimization • reduce counting, inventory checking, and packaging effort • encourage customers to order in full pallets, or full cases • create half-pallet or quarter-pallet units and encourage customers to order in such units

32. Pick from Storage • streamline picking by having primary picking area (other than secondary back-end storage) • smaller in size • better equipment • 10 to 20 times quicker • Is it possible to achieve the same throughput by picking directly from storage?

33. Pick from Storage • possible if • highly sophisticated logistics information system • random storage, intelligent slotting, activity balancing, dynamic wave planning • high degree of mechanization • disciplined workforce

34. Pick Task Simplification work element Method Requirements bring pick location to picker; batch picking; zone picking stock to picker systems; classifying and sorting orders traveling documenting automate information flow computer-aided order picking: automatic identification, light, RFID, headset reaching items at waist level vertical carousels, person-abroad AS/RS; miniload AS/RS searching stock to picker; direct picker to location; highlight location stock to picker systems; person-abroad AS/RS; pick-to-light systems extracting automated dispensing automatic item pickers, robotic order pickers counting weight counting; standard size scale on picking restocking automated restocking real time WMS socializing dedicated pick zone idling/waiting dynamic zone sizing; advanced job on hand real time WMS

35. Trade off for Traveling • reduce traveling by batch picking, zone picking, and wave picking • batch picking (i.e., grouping orders in picking) • zone picking (i.e., ungrouping lines (items) of orders in picking and regrouping lines into orders) • wave picking (i.e., all zones picking the same set of orders at the same time and regrouping items into orders)

36. Case StudyDallari, F., G. Marchet, and M. Melacini (2009) Design of Order Picking System, International Journal of Advanced Manufacturing Technology, 42, 1-12

37. order characteristics Design of an Order Picking System order picking system: equipment, layout, human resources, etc. strategic level considerations

38. Factors to Consider • order characteristics • individual orders: frequency, number of lines, quantity requested, shape and weight of items, etc. • aggregate effect • average number of orders per day, total number of SKU

39. Grouping of Items • different ways, e.g., by size, frequency, nature, etc. • case study • by size • average # of lines  15 lines • possibly sub-division in group

40. Observations from Empirical Studies

41. Empirical Study • picking methods observed from 68 warehouses in Italy • from trade journals, interviews of MHE suppliers, and interviews of warehouse management • small- to medium-sized companies, of revenue greater than 10 Euro • 5 picking methods • refinements, e.g., batch vs single order picking, setting of primary picking area

42. Empirical Study: 5 Picking Methods

43. Five Picking Methods Adopted by 68 Warehouses in Italy

44. Results from Statistical Analysis • SKUs  1,000: picker-to-parts • SKUs > 1,000 & small # of lines per day: parts-to-picker • large # of SKUs: hard to use picker-to-parts • large # of order lines: hard to use parts-to-picker • large # of order lines per day and large number of items: pick-and-sort and pick-to-box

45. Further Segmentation by Size • small orders (i.e., order volume  0.5 m3) and large orders (i.e., order volume > 0.5 m3) • pick-to-box: only for small orders • picker-to-parts: for both small and large orders • regardless of effect of # of order lines picked per day and the # of items managed when applied to large orders • parts-to-picker: both small and large orders

46. Further Segmentation by Size: Small Orders

47. Further Segmentation by Size: Large Orders

48. For the Specific Case Study

49. Characteristics of Groups • on average an order  15 lines

50. Results • a pick-to-box system • group 1 items (9,000 items; 7,450 order lines/day) • picker-to-parts systems • group 2 items (1,500 items; 2,500 order lines/day) • group 3 items (300 items; 50 order lines/day)