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

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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