Picking methods: from pick list to voice picking
Single order batch zone and digital picking technologies — and when each makes sense
When an order comes in, the goods must be found, assembled, and made ready for shipment—that's order picking. In most manual warehouses, picking is the single process that costs the most labor hours, and much of the time is spent not picking but walking: travel time between locations typically makes up the majority of total pick time. So good picking technique is about two things—choosing the right strategy for how orders are assembled, and using the right technology to guide the picker.
§The three basic strategies
Single order picking (discrete picking) is the simplest: one picker collects one order completely from start to finish. It produces few errors and is easy to learn but a lot of walking per order. Batch picking collects multiple orders' needs for the same items in one trip — the picker takes for example ten orders' total number of one item in one trip and distributes afterward to the orders. Zone picking divides the warehouse into zones with each its own picker; the order travels from zone to zone (pick-and-pass) or is assembled at the end (consolidation). Large warehouses often combine methods such as batch in the small goods zone and single order in the pallet zone.
| Strategy | Strength | Weakness | Suits |
|---|---|---|---|
| Single order | Few errors, simple | Lots of walking | Few, large orders |
| Batch | Minimises walking time | Requires redistribution | Many small orders with the same goods. |
| Zone | Pickers know their area | Requires coordination/consolidation | Large stocks with many product numbers |
§The technology: from paper to voice
The classic paper pick list still exists, but it has two weaknesses: it cannot check whether you took the right item and it does not update inventory balances continuously. With a hand scanner (pick-by-scan) you confirm each location and item by scanning the barcode — the system catches the error in the same second it happens. Pick-to-light places lamps and displays at each location: the light shows where and how much to pick and you confirm with a button press. Voice picking gives you instructions in a headset and lets you confirm with your voice — both hands are free and eyes are on the goods. Finally, goods-to-person systems like miniload and robot warehouses reverse the process so the goods come to the picker instead.
- 01Paper pick list
- 02Scanner: catches errors at source and continuously updates the WMS
- 03Pick-to-light: high pace in fixed picking zones with many small orders
- 04Voice: free hands — strong for heavy items and cold/frozen warehouses with gloves
- 05Goods-to-person: minimal walking time, but requires large investment
§The route and locations
Regardless of method, the welder protects themselves with a welding helmet with correct filter, flame-resistant clothing, gloves and if necessary respiratory protection. Eyes, skin and airways must be protected against arc light, heat/sparks and welding fumes respectively.
§Ergonomics in picking.
Picking is also body work. According to the Working Environment Authority's guideline D.3.1 on lifting, pulling and pushing, a lift is assessed on the basis of the load's weight and distance from the body — and repeated lifting in poor postures wears out, even when the individual load is light. Place heavy goods in the zone between knee and shoulder height, use lifting trolleys and pallet jacks, and switch between tasks so the same movement is not repeated all shift. A fast picker who lasts twenty years beats a lightning-fast picker who wears out in five.
“The fastest picking is the one where you don't have to go anywhere.”
— Basic principle in warehouse optimisation