1. Definitions and concepts

1.1 Notion of multi-purpose or flexible workshop

Batch plants traditionally produce high value-added products, in the range of 5 to 500 e/kg [1] . Annual production quantities are relatively modest, in the order of a few hundred tonnes. Under these conditions, a plant dedicated to the manufacture of a single product is faced with the following dilemma:

• year-round operation, leading to low equipment volumes and high labour costs;

• or operate for a few months a year: the result is higher volumes and more bearable labor costs, but investments that are harder to recoup;

• product lifetimes are highly variable,...