What is parallel picking?

Parallel picking means that a customer order is first split into several parallel sub-orders by the warehouse management system. Later, the sub-orders are picked in parallel by multiple pickers in the warehouse zones (picking zones) and then recombined into a single order.

Details and a simple explanation of parallel processing

Order-based data entry is first performed in the merchandise management system. To optimize the total picking time (picking performance), the customer order is divided among several warehouse zones in the warehouse management system and prepared as partial orders.

Each order is then picked in parallel by multiple pickers in separate picking zones, placing the items into containers or shipping cartons (according to the pick list). From the picker’s perspective, a parallel partial order is no different from a normal order.

Each item in the order is picked using the specified picking method (e.g., pick-by-light, Voice Picking,^{Pick-by-Point®}, etc.). The goods are removed from the storage location in the usual manner. To optimize picking time in the process, the grasping time, idle time, and travel time should be kept as short as possible.

Once all the goods have been fully picked, the individual picking orders must be consolidated again within the process. To minimize travel distances, sorters or conveyor systems are often used for this purpose.

Start of parallel sub-tasks

To ensure that parallel sub-orders start at the optimal time, the material flow system must first calculate the optimal start time for each order. In particular, order lead times must be taken into account. The goal of this optimization is to ensure that all parallel sub-orders are completed as simultaneously as possible, thereby eliminating any waiting times.

Consolidation of parallel sub-orders

Once parallel picking has been completed in the warehouse, the individual orders are consolidated based on order requirements. The consolidation time should be as short as possible for the picker. The following methods can be used for this purpose:

• Picking Methods for Pallet Distribution (Put-to-Point)
• Storing goods in a flow rack (optimal "put-to-light" picking method)
• Manual sorting of goods using handheld devices (very outdated and slow)

Once all items have been consolidated by order, they can be shipped. This article does not address the selection of the optimal picking method.

Advantages of parallel picking

Depending on the design of the supporting picking systems, parallel picking offers the following advantages:

• High performance through order-based picking in separate storage zones (important: accurate ABC analysis).
• Shorter handling times by distributing tasks among multiple pickers.
• Optimal use of picking methods such as Pick-by-Light, Voice Picking,^{Pick-by-Point®}, etc., when picking partial orders.

Disadvantages of parallel picking

The disadvantages are defined as follows:

• This process is only practical for large warehouses with many storage zones (picking zones) and a large number of items.
• Due to the warehouse structure, it is not always possible to optimally allocate customer orders to subcontracts.
• Significant technical effort is required to consolidate the parallel orders.

Conclusion

Parallel picking is suitable for large warehouses with many storage zones and a high degree of automation (pick-by-light, Voice Picking, conveyor systems, sorter systems) to ensure fast order fulfillment. Multiple pickers can process a customer order simultaneously. Consolidating the partial orders is a complex process and must be closely coordinated with the picking operations via the material flow system.