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 mobile storage unit 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. Vertical Carousel 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. Summary Characteristics of Alternative Broken Case Picking Systems
Auto. Disp.
Miniload AS/RS
Vertical Carousel
Horiz. Carousel
Storage Drawers
Flow Racks
Bin Shelving
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. 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
items
Qty
lines of items
volume and weight of items in lines

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

24. Schemes of Picking Orders
documentation, reaching, searching, extracting, counting, restocking
do not change (much) with schemes of picking orders
sequencing orders; un-grouping, grouping and regrouping lines
traveling distance and sorting effort
change with schemes of picking orders
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
Batch Picking
Downstream Sortation
Manual Sortation
Split Single Order Picking
Automated Sortation
Complete Single Order Picking

26. Single-Order Picking good for long traveling distance for a few items
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. Methods to Assemble Orders
zone 1
zone 2
zone 3
progressive order assemble
downstream sortation
zone 1
zone 2
zone 3
sort-ing

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
traveling
bring pick location to picker; batch picking; zone picking
stock to picker systems; classifying and sorting orders
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 Study Dallari, F. , G. Marchet, and M
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. Design of an Order Picking System
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 aggregate effect
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 case study
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 picker-to-parts systems
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. 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 m3 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 m2 picking area, operated by 12 pickers

52. Equipment and OPS for Groups 2 & 3 Items
homogeneous items with each outflow  1 m3 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 m2 picking area, employing 5 pickers

53. Results

54. Results