order picking, “bucket brigades”_part-1
DESCRIPTION
Warehouse ManagementTRANSCRIPT
Supply Chain & Logistics
Strategic Warehouse Management
Order PickingOrder Picking
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Why Is Picking Important?
Order picking is the highest priority in the warehouse for productivity improvements
Receive/Put-away Picking Shipping Support0
10
20
30
40
50
60
Proportion of Time and Money Spent on Major Activities
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Why Is Picking Important?
Order picking is the most labor intensive functionOrder picking has become increasingly difficult to manage• Smaller orders• More SKUs
Quality and service focus has resulted in efforts to• Reduce damage• Increase accuracy• Reduce transaction times
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Order Picking Activities
Travel
Search Picking
Paperwork
62.0%
16.0%12.0%
10.0%
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Issue Pack Optimization
Encouraging customers to order in full pallet or pallet increments• Enables the creation of efficient pallet, half-pallet
or quarter-pallet storage quantitiesChallenges• Requires agreement and coordination with enough
customers to impact the operation• Creates an inventory cost and picking cost tradeoff
to be considered
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Pick-From-Storage
Why so many storage and picking locations?• Broken and full-case picking from a large reserve
pallet location is highly unproductive
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Order Picking
ReplenishP
utaw
ay
OrderPicking
Putaw
ay
Forward PickingReserveStorage
Packing, Sorting& Unitizing
Receiving ShippingCross-docking
Pallet Picking
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Pick Task Simplification
Eliminate and Combine Order Picking Tasks When Possible
Traveling & Extracting Items• Bring pick locations to picker
Documentation• Automate information flow
» Pick-to-light» RF
Picking and Sorting• Present items at waste level• Sort into totes as picked
Sorting and Packing• Small cube items can be packed directly into shipping
containers
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Order Batching
Batch orders to reduce total travel timeIncrease the number of items picked per picking tour• Reduces travel time per pick
Single line orders• Provide a natural group of order to be picked
together» Minimal downstream sortation
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Order Batching
Single Order Picking• Grocery store model• Maintains order integrity
Batch Picking• Multiple orders picked at a time• Reduces travel time• Results in additional sortation
Zone Picking• A portion of an aisle, multiple aisles, or machines
assigned to an operator for picking• Enhances productivity, accuracy and
housekeeping
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Order Picking – Additional Definitions
Picking – the process of finding and removing stock from its storage areaWave picking – defined amount of work for pickers for a set timeBatch picking – picking a particular item that is in many orders & sorting them later by orderSequential picking – items picked in sequence from storage areas on the same side of an aisleCross picking – items picked in sequence from storage areas on both sides of an aisle
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Order Picking – Additional Definitions
Progressive Order Assembly• Contents of an order are passed from one zone to
the next until the order is assembled• Zone Skipping – if the order has no item from a
specific zone, it is passed on to the next zoneDownstream Sortation• There is no specific order designated during the
order picking process• Orders are assembled separately• Costs to accumulate and sort can run into the
millions
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Cluster Picking
Batch order picking for increased productivity
• Simultaneously "order pick" a set of orders (a “cluster”) in one pass through the warehouse
• Configurable number of orders per cluster
• Interleave picks from each cluster to minimize travel path
• Picker can Skip or Cancel task within clusters
A B
C D
1
23
45
Pick Path
Push Cartwith Totesor Boxes
6
A B
C D
1
23
45
Pick Path
Push Cartwith Totesor Boxes
6
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Serpentine Flow
The picker-to-part order picking method
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Zone Picking
Each of five workers remain in their zones (in this case an aisle). Here, this zonepicking operation is composed of five, independent, discrete picking operations.
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The “Fast-pick” Or “Forward-pick” Area
ReservesArea
Forward pickArea
Receiving
Restocking Primary picking
Reservespicking
Shipping
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Trade-offs With A “Forward Pick” Area
A forward pick area increases the pick density by concentrating a large number of SKU’s within a small physical space.On the other hand, it introduces the activity of restocking.Also, in general, a forward pick area concerns the picking of smaller quantities and involves more sophisticated equipment than the picking activity taking place in the reserves area. So, its deployment requires some capital investment in equipment and (extra) space.
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Picking Method Selection
Discrete Zone
Batch Zone-Batch
LOW
HIG
H
MIXED
Line
s an
d C
ube
per O
rder
Order Mix
PURE
If items in most orders from same family (pure), then can establish separate zone for each family with little zone-to-zone transfer neededDiscrete picking appropriate if single order has high number of lines and/or cube
Method
Pickers per Order
Orders per Picker
Discrete Single Single
Zone Multiple Single
Batch Single Multiple
Zone-Batch Multiple Multiple
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Slotting
For Each SKU, DetermineStorage modeSpace allocationStorage location
Based on item popularity and the warehouse activity profile
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Flow-Cube Distribution for Pallet Storage
Items in the bottom right-hand corner of the distribution generate the most picking activity per unit of storage space and should be assigned to the most accessible racks.Items in the top right-hand require equipment with greater cube utilization while still being accessible.
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Flow-Cube Distribution for Piece Storage
Items in the bottom right-hand corner of the distribution do not have to be replenished as frequently as those in the top right-hand corner and can be stored in carousels and dispensers, which allow for very efficient picking but are difficult to replenish.
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Pick Sequencing
Sequence pick location visits to reduce travel timeThe “Traveling Salesman Problem” (TSP)• Complex mathematical modeling
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A serpentine pick path can result in unnecessary travel (in this case along aisles 3 and 6).
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A modified path outline that sorts aisles 4–6 but not their locations.
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Example of branch-and-pick
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Layout on the right allows the operator more flexibility for items C,D,E
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Popular items should be stored as close to the travel path as possible
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Bucket Brigades
Coordinating workers who are progressively assembling product along a flow line in which there are fewer workers than stationsCarry work forward, from station to station, until someone takes over your work; then go back for moreNo unattended work-in-process is allowed in the systemWorkers carry each product as far toward completion as possibleSequenced from slowest to fastest along the direction of material flowA classic Pull System
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Bucket Brigades
Insignificant Walkback Time• The total time to assemble a product is
significantly greater than the total time for the workers to handoff their work and walk back to get more work
Total Ordering Of Workers By Velocity• Each worker can be classified be the speed with
which they perform their tasksSmoothness, Predictability Of Work• The work-content of the product is spread
continuously and uniformly along the flow line
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Bucket Brigade Impact
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Bucket brigades at Wawa
Switching to bucket brigades allowed Wawa to use narrow aisles without congestion because there is no passing under bucket brigades. Narrow aisles also freed up space for two additional aisles.