ESTIMATING CYCLE TIME IN COMPLEX JOB SHOPS

Article type: Research Article

Authors: Neureuther, Brian D.

Affiliations: Analytical Department, School of Business, Indiana State University, Terre Haute, IN 47809. E-mail: [email protected]

Abstract: The development of Little's Law has been shown to give relatively precise and replicable estimates of the true cycle time in a variety of production (or network queuing) systems. The majority of the work performed using Little's Law has been done with queuing systems involving single products and single operations. However many queuing systems, such as semiconductor fabrication, are much more complex and involve several products with hundreds of operations. In this paper we compare the expected cycle time as computed by Little's Law to the actual cycle time determined from simulation analysis in a single and multiple product, multiple operation semiconductor fabrication system (a network queue environment). It was found that under simple environments, Little's Law works well. However, in complex job shop processes, such as semiconductor manufacturing, it does not. Factors that cause Little's Law to break down and the factors that are required to accurately estimate cycle time in complex job shops are addressed.

Journal: Journal of Integrated Design & Process Science, vol. 6, no. 3, pp. 93-104, 2002