Piece Picking Methods

Piece picking, also known as broken case picking or pick/pack operations, describes systems where individual items are picked.  Piece pick operations usually have a large sku base in the thousands or tens of thousands of items, small quantities per pick, and short cycle times. Mail order catalog companies and repair parts distributors are good examples of piece pick operations.

Basic order picking
In the most basic order-picking method, product is stored in fixed locations on static shelving or pallet rack.  An order picker picks one order at a time following a route up and down each aisle until the entire order is picked.  The order picker will usually use some type of picking cart.  The design of the picking flow should be such that the order picker ends up fairly close to the original starting point.  The picking document should have the picks sorted in the same sequence as the picking flow.  Fast moving product should be stored close to the main cross aisle and additional cross aisles put in to allow short cuts.  Larger bulkier items would be stored towards the end of the pick flow.  This basic order picking method can work well in operations with a small total number of orders and a high number of picks per order.  Operations with low picks per order will find the travel time excessive in this type of picking and operations with large numbers of orders will find that the congestion from many pickers working in the same areas slows down the processing.

Batch picking / Multi-order picking
In batch picking, multiple orders are grouped into small batches. An order picker will pick all orders within the batch in one pass using a consolidated pick list.  Usually the picker will use a multi-tiered picking cart maintaining a separate tote or carton on the cart for each order.  Batch sizes usually run from 4 to 12 orders per batch depending on the average picks per order in that specific operation.  Batch picking systems may use extensive logic programmed to consolidate orders with the same items.  In operations with low picks per order, batch picking can greatly reduce travel time by allowing the picker to make additional picks while in the same area.  Since you are picking multiple orders at the same time, systems and procedures will be required to prevent mixing of orders.  In very busy operations, batch picking is often used in conjunction with zone picking and automated material handling equipment.  In order to get maximum productivity in batch pick operation, orders must be accumulated in the system until there are enough similar picks to create the batches.  This delay in processing may not be acceptable in same day shipping operations.

Zone picking
Zone picking is the order picking version of the assembly line.   In zone picking, the picking area is broken up into individual pick zones. Order pickers are assigned a specific zone, and only pick items within that zone.  Orders are moved from one zone to the next as the picking from the previous zone is completed (also known as "pick-and-pass").  Usually, conveyor systems are used to move orders from zone to zone.  In zone picking it’s important to balance the number of picks from zone to zone to maintain a consistent flow.  Zones are usually sized to accommodate enough picks for one or two order pickers.  Creating fast pick areas close to the conveyor is essential in achieving high productivity in zone picking.  Zone picking is most effective in large operations with high total numbers of skus, high total numbers of orders, and low to moderate picks per order.  Separate zones also provide for specialization of picking techniques such as having automated material handling systems in one zone and manual handling in the next.

Wave picking
A variation on zone picking and batch picking where rather than orders moving from one zone to the next for picking, all zones are picked at the same time and the items are later sorted and consolidated into individual orders/shipments.  Wave picking is the quickest method (shortest cycle time) for picking multi item orders however the sorting and consolidation process can be tricky.  Operations with high total number of SKUs and moderate to high picks per order may benefit from wave picking. Wave picking may be used to isolate orders by specific carriers, routes, or zones.

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