This paper deals with the problem of part input sequencing in an autom
ated flow shop system. The system consists of one input/output station
, two machines and one AGV, which is used for all part transfer operat
ions throughout the cell. The objective is the minimization of the mak
espan. This cell architecture has recently received considerable atten
tion in the literature. Here we consider the case in which the two mac
hines are equipped by a swapping device, allowing the AGV to exchange
a new part for the one released by the machine. A similar device exist
s for the input/output station. If the transportation times are small
enough, the problem can be formulated as a two-machine flow shop with
limited intermediate buffer, which is NP-hard. Here we analyze the pro
blem in the context of lot processing, i.e., when identical parts must
be processed consecutively. Each set of identical parts forms a lot.
The number of parts in the lot is the size of the lot. If the size of
the ith lot is larger than a value b(i), the problem can be formulate
d as a special case of TSP and solved in polynomial time. The cost str
ucture of this TSP generalizes that defined for the two-machine no-wai
t flow shop. Finally, we give a closed form expression for b(i).