As mentioned, the automotive industry is facing a continuously increasing demand for flexibility in production in the light of the variety of options how customers are able to configure their vehicles. Depending on the model over a billion variants are possible. Until now, the industry has addressed this complexity more or less universally by planning assembly lines for a given model and then controlling the production sequences by optimising them with respect to more or less physically motivated process restrictions and KPIs. The assembly line – once designed – remains essentially unchanged throughout the life cycle of the car model the line was organised for. In this way, of course, the assembly line with its physically fixed arrangement of production resources strictly determines the intra-logistical processes of the whole production and supply chain.
This production control and optimisation, known as sequencing, is directly subject to the ordering power of the physically fixed production line structure. Through its physical restrictions and requirements, this structure of the line strongly influences the connected supply processes and the necessary logistics. For example, the physically fixed production line results in the specification of minimum distances in the assembly sequence that must be kept between orders (vehicles) with particular features.
Despite the obvious advantages of the controllability of this organisation–controllable, as once the line is established, it will not be changed for several years over the entire life cycle of the model–it would lack the necessary flexibility for smaller series and significantly shorter life cycles of car models. For a hypothetical lifecycle of only three months instead of six or seven years, fixed production lines would lead to increasing costs and decreasing efficiency. A highly flexible production process organized within the inflexible structure of an assembly line would be doomed to failure, and the evaluation of its economic Key Performance Indicators would just confirm it.
