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OutlineOutline
small item storage and retrieval system
picking operations
case study
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Small Item Small Item Storage and Retrieval SystemsStorage and Retrieval Systems
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Picker-to-Stock Systems: StoragePicker-to-Stock Systems: Storage
bin shelving modular storage gravity flow rack space saving system
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Bin ShelvingBin Shelving
oldest method advantages
simple low initial cost variable bin content over time
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Bin ShelvingBin 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
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Modular Storage Drawer/CabinetsModular 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
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Gravity Flow RackGravity 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
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Space Saving SystemsSpace Saving Systems
mezzanines high floor height use mezzanines for secondary storage
mobile storage unit
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Picker-to-Stock Systems: RetrievalPicker-to-Stock Systems: Retrieval
cart picking tote picking man-up system robotic item picking
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Cart PickingCart 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
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Tote PickingTote Picking
picked items to totes totes on conveyors for pickers to carry or
push them around compartments on totes for multiple orders
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Man-up SystemsMan-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
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Robotic Item PickingRobotic Item Picking
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Stock-to-Picker SystemsStock-to-Picker Systems
carousel horizontal vertical
miniload
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HHorizontal Carousel
limited height a picker on multiple carousel
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VerticalVertical Carousel
shorter pick time than horizontal carousel better picking position
better item protection
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Miniload Automated Storage and Miniload Automated Storage and Retrieval SystemRetrieval System
low floor space requirement manual or automatic storage and retrieval
direction greater maintenance requirements
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Automated Item Automated Item Dispensing MachinesDispensing Machines
automated vending machine with conveyor or pneumatic system to send selected items to the collection point
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Summary Characteristics of Alternative Broken Summary Characteristics of Alternative Broken Case Picking SystemsCase Picking Systems
Auto. Disp.Miniload AS/RS
Vertical Carousel
Horiz. Carousel
Storage Drawers
Flow RacksBin
Shelving
Net Cost
Gross Cost
Pick Rate
Flexibility
Item Security
Mainten-ance
Human Factors
Floor Space Reqt.
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Summary Characteristics of Alternative Broken Summary Characteristics of Alternative Broken Case Picking SystemsCase 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 RacksBin
Shelving
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Chapter 8 Chapter 8 Picking Operations Picking Operations
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Picking OperationsPicking 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
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Typical Distribution of an Order Typical Distribution of an Order PickerPicker’’s Working Times Working Time
0%
10%
20%
30%
40%
50%
60%
55%
15%10%
20%
Traveling
Searching
Extracting
Other
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Schemes of Picking OrdersSchemes 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
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Schemes of PickingSchemes of Picking
Picking Schemes
Freeform Picking Zone Picking
Single Order Picking Batch Picking Progressive
AssemblyDownstream
Sortation
Split Single Order Picking
Complete Single Order Picking
Manual Sortation
Automated Sortation
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Single-Order PickingSingle-Order Picking
good for order integrity “large” orders or emergency orders
long traveling distance for a few items high distance traveled per line
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Batch PickingBatch 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
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Zone PickingZone 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
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Methods to Assemble OrdersMethods to Assemble Orders
progressive order assemble
zone 1
zone 2
zone 3
downstream sortation
zone 1
zone 2
zone 3
sort-ing
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Improvement of Picking OperationsImprovement of Picking Operations
issue pack optimization pick from storage pick task simplification order batching slotting optimization pick sequencing
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Issue Pack OptimizationIssue 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
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Pick from StoragePick 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?
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Pick from StoragePick from Storage
possible if highly sophisticated logistics information
system random storage, intelligent slotting, activity
balancing, dynamic wave planning
high degree of mechanization disciplined workforce
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Pick Task SimplificationPick Task Simplification
real time WMSdynamic zone sizing; advanced job on hand
idling/waiting
dedicated pick zonesocializing
real time WMSautomated restocking restocking
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
RequirementsMethodwork element
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Trade off for TravelingTrade 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)
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Case StudyCase Study
Dallari, F., G. Marchet, and M. Melacini Dallari, F., G. Marchet, and M. Melacini (2009) Design of Order Picking System, (2009) Design of Order Picking System,
International Journal of Advanced International Journal of Advanced Manufacturing TechnologyManufacturing Technology, 42, 1-12, 42, 1-12
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Design of Design of an Order Picking Systeman Order Picking System
strategic level considerations
order characteristics
order picking system:
equipment, layout, human resources, etc.
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Factors to ConsiderFactors 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
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Grouping of ItemsGrouping 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
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Observations from Empirical StudiesObservations from Empirical Studies
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Empirical StudyEmpirical 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
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Empirical Study: 5 Picking MethodsEmpirical Study: 5 Picking Methods
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Five Picking Methods Adopted Five Picking Methods Adopted by 68 Warehouses in Italy by 68 Warehouses in Italy
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Results from Statistical AnalysisResults 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
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Further Segmentation by SizeFurther 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
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Further Segmentation by Size: Further Segmentation by Size: Small OrdersSmall Orders
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Further Segmentation by Size: Further Segmentation by Size: Large OrdersLarge Orders
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For the Specific Case StudyFor the Specific Case Study
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Characteristics of GroupsCharacteristics of Groups
on average an order 15 lines
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ResultsResults
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)
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Equipment and OPS Equipment and OPS for Group 1 Itemsfor 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
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Equipment and OPS Equipment and OPS for Groups 2 & 3 Itemsfor 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
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ResultsResults
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ResultsResults