EQUIPMENT TYPES

The equipment used for storage and retrieval in order picking can be classified broadly as picker-to-part and part-to-picker types:

Picker-to-Part Systems

In picker-to-part systems, the order picker either walks or rides a vehicle to the pick location. Since the picking activity occurs within an aisle, this class of systems is sometimes referred to as "in-the-aisle" systems.

The major equipment groups under the heading of picker-to-part systems are

• bin shelving
• modular storage drawers/cabinets
• gravity flow rack
• person-aboard automated storage and retrievals systems (AS/RS)

In picker-to-part systems, the walking time is significant. For maximizing the order pick rate (orders picked/unit time), determining the picking sequence is important.

Part-to-Picker Systems

In these types of systems, the pick location is brought to the picker, Usually by a mechanical device.

In part-to-picker systems, the travel time of the device is important. The search time for the picker is significantly reduced since the correct pick location is automatically presented. In well designed systems, this could bring large increases in the pick rate of the system. One must also consider the workload balance between the picker and the machine.

The major equipment groups under the heading of part-to-picker systems are

• carousels
• mini-load automated storage and retrieval systems (AS/RS)

Cost Comparison

Generally, picker-to-part systems are less sophisticated and hence less costly, in terms of initial cost, than are part-to-picker systems.

Batch Picking and Sorting Systems

It is often more effective for an order picker to retrieve items for many customers at the same time. This is called batch picking. When this method is used, we must separate the items belonging to each customer. Sorting systems are used for this purpose. The major types of sorting equipment are:

• conveyor
• picking cart
• sorting matrix (bin array)