Imperfect production processes have been focused during recent decades for optimum lot size calculation based on
average cost minimization. However, cycle time optimization has been ignored relatively when processes are imperfect
and inspection as a process is considered. Furthermore, the role of work-in-process inventory with respect to cycle
time has always been significant. Hence, this paper integrates work-in-process inventory and imperfect production
setup in order to optimize cycle time based on average cost minimization. A mathematical model is developed that
incorporate rework operation, rejected products produced, and inspection processes in addition to work-in-process
inventory. Cycle time is optimized based on total system cost minimization. Numerical example is also used to illustrate
the impact of the developed model as compared to the previously developed model. The impact of work-in-process
inventory and processes imperfection on optimum cycle time is highlighted by an example.