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Order processing and order picking Chen Zhou April 24, 2004 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 Generate Availability Loca tion Order processing
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Order processing and order picking Chen Zhou April 24, 2004
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
Generate Availability Loca tion Order processing
Another form of pick list: sequenced labels • Sequenced sticky labels
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
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
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?
How does storage affect picking • Type of equipment affect sku density • Sku density affect pick density • Slotting affect travel
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
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
Batch picking: multiple-order–one-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
Batching picking with push carts Pick to order specific containers, no sorting is required afterwards
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
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
Schematic of a picking zone Pick module Forward Reserve Sort to shipping docks Receiving docks
Restock Restock pick pick pick A graphical view of a pick module • A case picking zone
No Sorting is required Sorting is required Zone picking
Increase accuracy Reduce search time More zone picking, station lighting
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
A frame Automated dispensing Automated picking with A - Frame
Sorting • Manual • Barcode directed • Vision directed • High speed sorters
Sorting: High Rate Tilt Tray • 12,000 items/hr. • Unit sorter • Can sort to two sides
Shoe sorter High speed conveyor sorters Roller sorter
Pick to conveyor, sorting is required downstream. How would you characterize this?
Automated order fulfillment initiation • Container types • Labels and tracking
A frame Automated dispensing Automated picking with A - Frame
Expected piece sales for the top 500 items 366,756 400,000 350,000 300,000 250,000 Sales 200,000 150,000 100,000 4,582 50,000 0 500th sku by piece sales top sku by piece sales Pareto chart ($, cases, picks, …)
Conveyors in DCs • Conveyors become more and more popular • In the states, a DC can have miles of conveyors
What does conveyor do? Pick module Sort to shipping docks Receiving docks
Cont. • Conveyors • Transport • Buffer • Extends the good locations throughout the facility • Can yield very high throughput • Important for high throughput systems • Design issues
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
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
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