In Just-in-Time Manufacturing (JIT), layout shape involves establishing a hierarchy of manufacturing cells. Cells may be organised according to Group Technology principles where the aim is to make a family of parts that share common manufacturing processes. The cell comprises a group of unlike machines that are able to make a complete part. These are located very close together and are often arranged in a 'U' shape, to allow good communication, to minimise material handling and to minimise operator walking. Parts flow around the cell, in batches of one, without intermediate queuing. The number of operators in the cell is varied so that output matches demand. Typically, an operator tends more than one machine. The effect is to create automation, but with low cost and high flexibility (known as autonomation). Ultimately, cells can become semi-autonomous, controlling their own schedules, inspection and inventory. This autonomy is compatible with the concept of self-directed work teams.
JIT layout is non-static, so continuous improvement should be encouraged. One way is to use flow length monitoring whereby the total manufacturing distance, through a part or whole route, is recorded and displayed prominently. The idea is to encourage continuous reduction through participation. Related to this is process chart analysis, particularly to identify and reduce those steps that do not add value (e.g. inspection, storage, etc). At the heart of layout improvement lies the awareness that layout should be dynamic, taking every opportunity to reduce the flow length.
Bicheno, J., Cause and Effect JIT: The Essentials of Lean Manufacturing, 2nd Edition, PICSIE Books, Buckingham, England, 1994 (ISBN 0 9513829 5 0)