Flow patterns in plant layout

A flow pattern is the path followed by materials as they move from receiving, through the operations, to the shipping of the finished product. A good pattern avoids back-tracking and cross-flow, keeps distances short and allows expansion.

Common flow patterns

1. Straight line        2. L-shape           3. U-shape
 In -> -> -> -> Out      In -> -> -+          In  -> -> -+
                                   |                     |
                                   v                     |
                                  Out         Out <- <- -+

4. Circular (O)         5. S / serpentine    6. Odd angle
   +---->----+           In -> -> -> -+       In --\     /--> Out
   ^         |                        |             \   /
   |         v           +-- <- <- <- +              \_/
   +----<----+           |                     (short, direct
                         +-> -> -> -> Out       paths between areas)

1. Straight line: simple; used for short processes with few operations when the building is long enough. Easy to control, but may need a long building.
2. L-shape: used when the building shape or other facilities do not allow a straight line.
3. U-shape: receiving and shipping are on the same side, which allows common use of docks, supervision and material handling equipment. Common in JIT cells.
4. Circular: input and output are at the same point; useful when the operator or fixture returns to the start (e.g. pallets).
5. S-shape (serpentine): long process lines are folded to fit into a compact area.
6. Odd-angle: used for short runs where handling is mainly by conveyors, or where the space is irregular.

Factors for selection

Building shape and size, number and sequence of operations, product size and volume, material handling system, location of receiving and shipping, and possible future expansion.