Throughflow and U flow

Material Flow Planning
Planning the flow of materials is important in a warehouse. This is because with a plan, we would most likely be aware of the location of items in the warehouse and also the status and location of the handling equipments. With these information, better control of the warehouse can be achieved.

There are two main approaches of the plan of material flows. They are the 'U' flow and 'Through' flow.


'U' flow
A 'U' flow occurs when the goods receipt and dispatch functions are located at the same end of a warehouse building.

Products flow in at receiving, move in to storage in the back of the warehouse, and then to shipping, which is located at the adjacent to receiving on the same side of the building.

Items with higher throughput level are located closer to the loading bays. An example of a 'U' flow design can be seen in the diagram below.

Advantages of 'U' Flow

• Excellent utilization of dock resources because the receiving and shipping processes can share dock doors


• Facilitating cross-docking because the receiving and shipping docks are adjacent to one another and may be co-mingled
  
• Excellent lift truck utilization because put away and retrieval trips are easily combined and because the storage locations closest to the receiving and shipping docks are natural locations to house fast moving items


• Yields excellent security because there is a single side of the building used for entry and exit

'Through' flow

'Through' flow happens when separate loading bay facilities for outbound and shipping are provided, often at opposite end of warehouse.

Products flow in at receiving, move into storage, picking area and then the marshalling and depatch area in a straight line.

Items with a higher throughput levle are located at the center of the warehouse because the total distance travelled would be shorter. An example of a 'Through' flow layout design is shown on the diagram below.

The major disadvantage of a 'Through' flow layout is goods need to travel the full length of the warehouse, even for goods that have a higher throughput level. It is also harder to control and less flexible.

When is it better to adopt a 'Through' flow?

• When there is a risk of interference or confusion between goods in and goods out
  
• When goods inwards vehicles and dispatch vehicles are very different; for example differences in platform height or nature of unit load


• When a warehouse is connected to a production plan

Taken from:

• Edward H. Frazelle, World-class warehousing and material handling (2002)


• Johnny Tan, Oh Hui Ling, Cheryl Wee-Teo, Distribution Centre Management, Fourth Edition (2007)