Warehouse Order Picking Methods: How to Choose the Right System

The goal of order picking in any warehouse is simple: fulfill orders accurately and efficiently. The faster and more reliably orders leave the warehouse, the more revenue and profit your operation generates.

When designing an order picking strategy, there are a few common goals that most warehouse operations share:

• Minimize travel distance between picks
• Reduce picking errors
• Decrease total pick time per order

Discrete Order Picking

Discrete order picking is the most basic order picking strategy.  A picker picks one order at a time, from start to finish, before moving on to the next. This method is particularly useful for facilities with low order volumes.

Benefits of Discrete Order Picking:

• High accuracy: Processing one order at a time minimizes the risk of product mix-ups and reduces errors.
• Low upfront investment: Requires minimal equipment and simple organization or equipment implementation.
• Ideal for order personalization: Works well when orders vary significantly in size and quantity.

Disadvantages of Discrete Order Picking:

• Lower productivity: One order is picked at a time, limiting throughput.
• Higher labor and travel costs: Excessive walking and idle time can drive inefficiency, especially in large facilities.

Batch Picking

Batch picking groups multiple orders so they can be picked simultaneously. Order pickers group multiple orders on a picking cart as they travel through the different picking zones.

Benefits of Batch Picking:

• Increased efficiency: Reduces the picking time per order and improves overall throughput, particularly for larger order volumes.
• Optimized labor: Fewer pickers can handle higher order volumes compared to discrete order picking.
• Lower operational costs: Improved efficiency translates directly into costs savings.

Pick and Pass System

Pick and pass is where workers “pick” all required items from one zone and then “pass” the order to the next zone until the order is complete and routed to shipping.  Zones are often organized by SKU velocity, size, storage method, or product type.

Benefits of Pick and Pass:

• Increased flexibility: Adapts well to fluctuations in order volume or product mix.
• Minimal consolidation: Orders are built as they pass through zones, reducing post-pick handling when they arrive for packout.

Disadvantages of Pick and Pass:

• Unnecessary movement: Totes may pass through all the picking zones that don’t contain items for the order.

Increasing Throughput with Goods-to-Picker Systems

The largest gains in productivity and profitability that allow pickers to remain in a defined zone while equipment delivers orders to them.

Zone-routed conveyor systems, integrated with a Warehouse Management System (WMS), are among the most common solutions for higher-throughput order operations.

Zone Routed Picking System

A zone routed conveyor integrates conveyors, scanners, diverts, and WMS software to intelligently route order totes only to the zone needed to fulfill the order.

At each zone, workers or automated systems pick only the required SKUs before the tote moves on to fulfill the order.

Advantages of Implementing a Pick and Pass Conveyor System:

• Higher efficiency: Reduces picker travel time and speeds order assembly.
• Improved accuracy: Automated tracking minimizes picking errors.
• Better ergonomics: Less walking and lifting reduces worker fatigue and injury risk.
• Scalability: Modular design allows the system to grow with demand.

Disadvantages of Pick and Pass Conveyor System:

• Shared responsibility: Since there’s no single owner to each order, it can be harder to assign accountability for errors.
• Labor balancing challenges: Fluctuating SKU demand can overload some zones, unless the fast movers are carefully slotted throughout the picking zones.

Key Components of a Traditional Pick and Pass Conveyor System

• Accumulating Conveyors: Move totes through the picking zones and customize length, speed, and type to accommodate product types as needed.
• Sensors and Scanners: Monitor and track items as they move along the conveyor in real time to optimize the flow and inventory management.
• Sorters and Diverters: Route totes to appropriate zones or exit points according to order requirements.
• Control Systems: Integrate with the WMS to manage routing, and inventory databases to maintain accurate, up-to-date stock levels.
• Ergonomic Workstations: Often equipped with put lights to ensure accurate, efficient picking and putting in the appropriate totes.

The Role of AMRs

While zone routed conveyor systems have traditionally been the backbone of zone routed picking, Autonomous Mobile Robots (AMRs) are increasingly being added to these systems.

AMRs offer the ultimate flexibility, as they can be reprogrammed on the fly to travel to any zone in the warehouse. Although typically slower than conveyors, they offer greater operational flexibility.

Some AMR solutions go a step further by rethinking the picking workflow itself. Locus Robotics, for example, uses an automated bot-to-picker model that eliminates roaming by directing the worker to the next pick location, combining the flexibility of AMRs with faster, more efficient picking.

Choosing the Right Picking Strategy

There are many ways to lay out your warehouse and design an order picking system. From simple discreet picking to high-throughput, zone routed conveyor system, the right approach depends on your:

• Order volume
• SKU profile
• Labor availability
• Throughput requirements
• Budget

The best picking system is one that aligns with your operational demands and budget today while supporting growth tomorrow. Let our experts evaluate your current process and find the right order picking system for your operation.