Order Picking Methods

In warehouse management practice, various picking methods are used to process customer orders efficiently and accurately. There are four basic methods, classified into either single-stage or two-stage picking: 

• Order-Oriented, Serial Picking Without a Transfer Point (Single-Stage)
• Order-Oriented, Serial Picking with a Transfer Point (Single-Stage)
• Order-Oriented, Parallel Picking (Single Stage)
  
• Two-Stage Picking

Single-Stage Picking

The single-stage picking method is an order-oriented process where all items of an order are picked in a single run. This method is efficient in smaller warehouses or those with a low order volume, where the product range is manageable, and items are stored in an organized manner. It is characterized by simple organization and low coordination effort. Picking is performed manually (pick list) or with technical support, such as mobile data capture devices, RFID technology, or automated picking systems.

The single-stage order picking process begins with order acceptance and processing. Then, the required items are picked from the warehouse and checked before being packaged and prepared for shipping. The process ends with documentation and handover to the transportation service. 

Order-oriented serial picking is a picking method where an order is processed step-by-step and sequentially by pickers. Unlike parallel picking, where multiple pickers work simultaneously, processing here occurs in a fixed sequence. There are two variants of order-oriented serial picking:

Order-Oriented, Serial Picking Without a Transfer Point

A single picker processes the entire order. The picker moves through all warehouse areas (picking zones) and picks all items for the order.

Order-by-Order Processing: Each order is fully processed before the next one begins, meaning there is no parallel processing of multiple orders.

Sequence: Orders are processed in the order they are received.

Advantage: No need for coordination between multiple pickers or zones, as one person handles everything.

Disadvantage: Longer travel distances and higher processing times, as a single picker must go through all warehouse areas.

Order-Oriented, Serial Picking With a Transfer Point

Multiple pickers are involved, each responsible for their own zone.
An order is processed sequentially through different picking zones. The picking container is brought to a transfer point by one picker and handed over to the next, who picks the remaining items in their zone.
This process continues until the order has been processed through all relevant zones and is complete.

Advantage: Each picker focuses only on their zone, which can be more efficient than a single picker handling everything.

Disadvantage: The process requires coordination at the transfer points and may result in waiting times until the next picker can take over the container.

Order-oriented serial picking without a transfer point is a simple and low-coordination method but has longer processing times. With a transfer point, the process becomes more efficient through division of labor, though at the cost of increased complexity at the handover points.

Order-Oriented, Parallel Picking 

The order-oriented, parallel picking method splits a customer order into several sub-orders that are processed in parallel by multiple pickers in different warehouse areas. Key characteristics of this method include:

• Spatial separation of warehouse areas: The warehouse is divided into multiple areas, and each picker only processes their assigned area.
• Parallel Processing: Multiple pickers simultaneously pick the items needed for the same order.
• Collection Point: After completing their sub-orders, pickers bring the items to a central point (collection point) to complete the order.

Advantages:

• Shorter travel distances: Each picker operates only within a specific warehouse area, reducing travel distances.
• Shorter processing times: Since multiple pickers work simultaneously, the order can be completed faster.

Disadvantages:

• Coordination required: Good coordination between pickers is necessary to ensure all items arrive at the collection point on time.
• Collection Point Required: An additional step is needed to bring the items together at the collection point.

This method is often used in larger warehouses with a diverse product range to increase picking efficiency.

Two-Stage Picking ("Batch Picking" or "Two-Stage Order Picking")

Two-stage picking is a method in logistics where multiple customer orders are grouped into a batch and processed in two successive stages.

This method aims to increase efficiency in order processing and picking processes.

1. First Stage (Item-Based Picking)

In this phase, items are picked not based on individual orders but according to a common attribute, often based on item or product groups. The goal is to consolidate all items for multiple orders in a single pass to optimize travel and picking times. The picker moves through the warehouse and picks the required products in bulk, without yet assigning them to specific customer orders.

2. Second Stage (Order-Based Picking)

In the second stage, the collected items are allocated to individual customer orders. The products are sorted and assigned to specific orders, usually at a sorting area or through an automated sorting system.

Advantages of Two-Stage Picking:

Reduced travel distances: Picking items for multiple orders in a single run saves time and reduces unnecessary movement.

Increased efficiency: This method reduces the number of picking operations and allows faster order processing.

Better use of picking capacities: Since picking is not order-specific, larger quantities can be handled more efficiently.

This method is especially useful in environments where many small orders need to be processed, or when warehouses need to handle high order volumes while minimizing picking times, such as in e-commerce or grocery delivery services.

Overall, two-stage picking enables a significant increase in efficiency and is widely used in modern warehouse management and logistics systems.