© 2011, Global Institute of Flexible Systems Management Flexible System giftjourn@l Global Journal of Flexible Systems Management 2011, Vol. 12, Nos. 1 & 2, pp 81-89 Introduction Increased global competition attracted the business leaders and policy makers to turn their attention towards productivity and quality issues. In the present competitive scenario, manufacturing industries are facing great challenges for their survival. In the modern manufacturing environment, FMSs have evolved to meet the globalized market challenges. The particular characteristic of FMS is its capacity to operate effectively and efficiently under the changing market and technological production conditions (Angelo et al., 1996). Gupta and Buzacott (1989) observed that there is no uniformly agreed definition of the term FMS. According to Stockton and Bateman (1995), flexibility is the ability of a manufacturing system to change quickly and economically between existing part types, operation routes of components, operations on a component, production volumes, and capability to add new part types and new processes to the system. The flexibility is gained at the Performance Optimization of an Imbalanced Flexible Manufacturing System Using Taguchi Approach Ravindra Kumar Mechanical & Automation Engineering Department, GPM College of Engineering, Delhi. India E-mail address: ravi3000@gmail.com Abid Haleem Mechanical Engineering Department, Jamia Millia Islamia, Delhi. India Suresh K. Garg Production & Industrial Engineering Department, Delhi Technological University, Delhi. India Rajesh K. Singh Indian Institute of Foreign Trade, Delhi. India Abstract Considering the diverse range of manufacturing capabilities of modern manufacturing systems, uniform distribution of load on the workstations (WSs) is difficult to achieve as some of the WSs are required to process more parts than others or sometimes processing time of a WS can differ from one part to the other. These situations lead to unbalancing of the manufacturing system. The objective of this paper is to study and optimize the performance of an imbalanced Flexible Manufacturing System (FMS) under different operating environments. The FMS under consideration manufactures three types of parts having different processing characteristics. The experimental variables for the study are buffer capacities at the WSs, reduction in processing time of bottleneck WS, WSs processing time distribution, and parts release control. Throughput, average work-in-process (AWIP) and Average Throughput Time (ATT) are taken as performance measures. Taguchi approach is used to analyze the effects of above variables and establish the combinations of best factor levels to get the optimal performance. All variables are found to affect the performance to some extent. Reduction in processing time of the bottleneck WS and processing time distribution affected the performance of the system severely. The best factor level combinations differ for parts having different processing characteristics. This paper may help industry in analyzing the performance of an imbalanced FMS. Keywords: bottleneck, buffer capacity, imbalanced flexible manufacturing system, parts release control, taguchi, workstation expense of a complex control system required to control the processing workstations and the material handling system. FMS is an integration of Computerized Numerical Control (CNC) machines and a material handling system. The three primary parts of the system are CNC machine centers with automated tool changes, a material handling system and a mainframe computer to control the overall system. According to Klahorst (1981), FMS is a group of machines and related equipments brought together to process a group or family of parts and includes some primary and secondary components for a complete FMS. Ranky (1983) has defined an FMS as a system dealing with high level distributed data processing and automated material flow using computer-controlled machines, assembly cells, industrial robots, inspection machines and so on, together with computer integrated material-handling and storage systems. Meredith (1989) has been defined FMS as “a group of machines and related equipments brought together to