Order processing and order picking

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Order processing and order picking

• Chen Zhou
• April 24, 2004

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Objective

• To understand the challenges in order picking
• To understand the strategies in order picking
• To link the strategies with our key measures
  pick density and sku density

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Order processing
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Another form of pick list sequenced labels

• Sequenced sticky labels

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Other form or pick list

• Data table for PLC for pick to light
• Sequenced voice instructions to pick to voice
  (later)
• Instructions to automated systems

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Issues in order processing

• Objectives
• Minimize travel (or other handling)
• Subject to
• Time window, batch to waves
• Day in a week
• Departing time
• Items to pass to other DCs
• WMS normally support this function.
• It requires customization and adaptation

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Order picking
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Order picking

• Most demanding operation 55 of operation cost
• Amazon.com
• Office depot
• Big-box retailer DCs
• Spare parts DC
• Grocery DC
• Why does picking cost more than put away?

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How does storage affect picking

• Type of equipment affect sku density
• Sku density affect pick density
• Slotting affect travel

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Simple strategy one-order-one-picker

• Pick one-line at a time
• Pick-pack-ship one customer order at a time
• Straightforward
• Small orders low pick density (Amazon)
• Large orders Wal-Mart store order

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Order picking strategy fast pick area

• Fast pick or forward area low volume reserve
  restocking
• Higher pick density in forward
• Infrequent replenishment from reserve with large
  volume
• Double handling
• Models in the book which one should go to fast
  pick and how much to put there for a fixed fast
  pick area

Reserve
Forward/ Fast pick
Restock
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Batch picking multiple-orderone-picker

• Batch picking
• Combine small orders into the same trip
• Higher pick density
• Orders of small items (relative to the equipment)
• If orders are mixed during picking, sorting is
  needed later

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Batch picking of large orders with truck
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Batching picking with push carts
Pick to order specific containers, no sorting is
required afterwards
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Time based batching wave picking

• Many DCs organize batches based on time window
• Truck/ship/train departure times
• Shifts
• Cycle times
• Delivery requirements
• Designations
• Beijing wave
• 10 AM wave
• Yellow wave

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Zone picking one-order-multiple-picker

• Zone can be for multiple order also (batching
  zoning)
• Can achieve extremely high pick density
• Sorting is needed if not into order specific
  containers

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Schematic of a picking zone
Pick module
Forward
Reserve
Sort to shipping docks
Receiving docks
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A graphical view of a pick module

• A case picking zone

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Zone picking

• No Sorting is required

• Sorting is required

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More zone picking, station lighting

• Increase accuracy
• Reduce search time

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Put-to-light

• Open a case, put items into light indicated boxes
• Similar to zone picking with changing skus in a
  zone

Put as indicated
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Automated picking with A - Frame

• A frame
• Automated dispensing

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Sorting

• Manual
• Barcode directed
• Vision directed
• High speed sorters

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Sorting High Rate Tilt Tray

• 12,000 items/hr.
• Unit sorter
• Can sort to two sides

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High speed conveyor sorters
Roller sorter
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Checking, packing and packaging
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Shipping
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How would you characterize this?
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Automated order fulfillment initiation

• Container types
• Labels and tracking

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Automated picking with A - Frame

• A frame
• Automated dispensing

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Packing
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Shipping
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Other returns
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Pareto chart (, cases, picks, )
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Conveyors in DCs

• Conveyors become more and more popular
• In the states, a DC can have miles of conveyors

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What does conveyor do?
Pick module
Sort to shipping docks
Receiving docks
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Cont.

• Conveyors
• Transport
• Buffer
• Extends the good locations throughout the
  facility
• Can yield very high throughput
• Important for high throughput systems
• Design issues

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Order picking summary

• Pick list generation
• Order picking strategies
• Batching
• Zoning
• Forward/reserve
• Common pick area
• Order picking technologies
• Pick to light/put to light
• Pick to voice
• Automated order assembly systems
• Pick modules

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Warehousing Summary

• Warehousing and DC
• Operations inventory, flow line dynamics,
  scheduling, planning
• Time Spatial problem
• Distances,
• Contours,
• COI based assignments
• Storage methods
• Order picking strategies

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Order picking

• Forward/reserve
• Which sku?
• Space sharing for given sku and V
• General problem
• Common pick area
• Batch picking
• Batch size, lot sizing, worker and route
  schedule,
• Zone picking
• (Dynamic) line balancing problem
• Readings and home works