Abstract:
In order to cope with more realistic production scenarios, scheduling theory has
been increasingly considering assembly job shops. Such an effort has raised
synchronization of operations and components as a major scheduling issue. Most
effective priority rules designed for assembly shops have incorporated measures
to improve coordination when scheduling assembly structures. However, by
assuming a forward loading, the priority rules designed by these studies schedule
all operations as soon as possible, which often leads to an increase of the workin-
progress level.
This study is based on the assumption that synchronization may be improved by
sequencing rules that incorporate measures to cope with the complexity of
product structures. Moreover, this study favours the idea that, in order to
improve synchronization and, consequently, reduce waiting time, backward
loading should be considered as well. By recognizing that assembly shop
structures are intrinsically networks, this study investigates the feasibility of
adopting the Critical Path Method as a sequencing rule for assembly shop.
Furthermore, since a Critical Path type scheduling requires a precise
determination of production capacity, this study also includes Finite Capacity as
a requisite for developing feasible schedules.
In order to test the above assumptions, a proven and effective sequencing rule is
selected to act as a benchmark and a simulation model is developed. The
simulation results from several experiments showed significant reduction on the
waiting time performance measure due to the adoption of the proposed critical
path type priority rule.
Finally, a heuristic procedure is proposed as a guideline for designing scheduling
systems which incorporate Critical Path based rules and Finite Capacity
approach.