Abstract-In this paper, the authors studied the effects of process commonality and uncertain factors (viz. lead time, machine breakdown etc.) on deliverable parameters of a multi product, multi-period and multistage production system. The throughput of finished products and average production time of the system are examined. Simulation models are developed, verified and validated with the historical data from a company. Simulation package, namely WITNESS is used for this research. Analyses show that enclosure of common process in manufacturing system is always beneficial over the noncommonality environment, especially i) in uncertain situations, ii) for long procurement lead time of components and iii) when the number of parts increase in the system. The combination of uncertain factors has more impact on outcomes (throughput and average production time) compared to the individual factor.