These also include partially automatic assembly plants. Their special feature is optimization according to the LEAN production philosophy. One central element is clearly structured and ergonomic workplace design. For workpiece transport, workpiece holder circulation systems with loose sequencing are used which comprise a U cell accommodating the assembly staff. Material feed is from the outside in; the distances between the stations are minimized. Thus, this design permits maximum flexibility as regards the deployment of staff in case of fluctuating quantities. The degree of automation can be chosen depending on the location in question.