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

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

2 2 Small Item Storage and Retrieval Systems

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

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

5 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 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 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 8 Space Saving Systems mezzanines high floor height use mezzanines for secondary storage mobile storage unit

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

10 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 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 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 13 Robotic Item Picking

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

15 15 H Horizontal Carousel limited height a picker on multiple carousel

16 16 Vertical Vertical Carousel shorter pick time than horizontal carousel better picking position better item protection

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

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

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

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

21 21 Chapter 8 Picking Operations

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

23 23 Typical Distribution of an Order Picker s Working Time 55% 15% 10% 20% TravelingSearchingExtracting Other

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

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

26 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 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 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 29 Methods to Assemble Orders progressive order assemble zone 1 zone 2 zone 3 downstream sortation zone 1 zone 2 zone 3 sort- ing

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

31 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 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 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 34 Pick Task Simplification real time WMSdynamic zone sizing; advanced job on hand idling/waiting dedicated pick zonesocializing real time WMSautomated restockingrestocking scale on pickingweight counting; standard sizecounting automatic item pickers, robotic order pickersautomated dispensingextracting stock to picker systems; person-abroad AS/RS; pick-to-light systems stock to picker; direct picker to location; highlight location searching vertical carousels, person-abroad AS/RS; miniload AS/RS items at waist levelreaching computer-aided order picking: automatic identification, light, RFID, headset automate information flowdocumenting stock to picker systems; classifying and sorting orders bring pick location to picker; batch picking; zone picking traveling RequirementsMethod work element

35 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 36 Case Study Dallari, F., G. Marchet, and M. Melacini (2009) Design of Order Picking System, International Journal of Advanced Manufacturing Technology, 42, 1-12

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

38 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 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 40 Observations from Empirical Studies

41 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 42 Empirical Study: 5 Picking Methods

43 43 Five Picking Methods Adopted by 68 Warehouses in Italy

44 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 45 Further Segmentation by Size small orders (i.e., order volume 0.5 m 3 ) and large orders (i.e., order volume > 0.5 m 3 ) 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 46 Further Segmentation by Size: Small Orders

47 47 Further Segmentation by Size: Large Orders

48 48 For the Specific Case Study

49 49 Characteristics of Groups on average an order 15 lines

50 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)

51 51 Equipment and OPS for Group 1 Items different storage methods and identification technologies storage methods gravity flow racks for high throughput items (500 items; more than 1 m 3 per week) shelves for the rest primary plus secondary storage for some shelved items identification technologies pick-to-light for 10% of items accounting for 70% of order lines radio frequency terminals for the rest a 4,000 m 2 picking area, operated by 12 pickers

52 52 Equipment and OPS for Groups 2 & 3 Items homogeneous items with each outflow 1 m 3 per week a pallet storage location for each item matching the unit loads received in the warehouse picker-to-parts, first level as the forward area and upper levels as the reserve area group 2 items: batch picking policy group 3 items: single-order picking policy a 6,000 m 2 picking area, employing 5 pickers

53 53 Results

54 54 Results

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