5 th International & 26 th All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12 th –14 th , 2014, IIT Guwahati, Assam, India 384-1 SCHEDULING A STOCHASTIC DYNAMIC JOB SHOP MANUFACTURING SYSTEM WITH SEQUENCE-DEPENDENT SETUP TIMES Pankaj Sharma 1* , Ajai Jain 2 1* Department of Mechanical Engineering, National Institute of Technology, kurukshetra, India. Pin code: 136119, Email Id.: pankajsharmagju@gmail.com 2 Department of Mechanical Engineering, National Institute of Technology, kurukshetra, India. Pin code 136119, Email Id.: ajayjainfme@nitkkr.ac.in Abstract In this paper, an attempt is made to address a stochastic dynamic job shop scheduling problem with sequence- dependent setup times. The objective of the problem is to determine a schedule that minimizes the mean flow time and mean tardiness performance measures. A discrete event simulation model of the stochastic dynamic job shop manufacturing system is developed for the investigation purpose. Three dispatching rules i.e. shortest processing time (SPT), shortest setup time (SIMSET) and earliest due date (EDD) are incorporated in the simulation model. The simulation experiments are conducted under due date tightness factor of 3, shop utilization percentage of 90 and setup times less than processing time. The results indicate that the SIMSET rule provides better performance for mean flow time while the SPT rule provides better performance for mean tardiness measure. Keywords: scheduling, stochastic dynamic job shop, sequence-dependent setup times, dispatching rule 1 Introduction In a shop, production scheduling is concerned with allocation of set of jobs on a set of production resources over time to achieve some objectives. In a job shop,jobs are processed on a set of machines.Each job has its specific operation order. Job shop scheduling problems occurs in many practical situations such as aerospace industries, fabrication industries and printing industries. The job shop scheduling problem is a combinatorial optimization problem and one of the most complex problemamong various production scheduling problems (Gareyet al. 1976, Xionget al. 2013).In a dynamic job shop scheduling problem jobs arrive continuously in the manufacturing system. Stochastic dynamic job shop (SDJS) scheduling problemrepresent the practical environment of a job shop scheduling problemwherein at least one parameter of the job(i.e. release time/processing time or setup time) is probabilistic (Kim and Bobrowski 1994,Kim and Bobrowski 1997). Setup time is a time required to prepare the resources such as machines to perform aoperation (Ali and Soroush 2008). A setup operation often occurs while shifting from one type of operation to another. Sequence-dependent setup time depends on both current and immediately preceding operation(Ali and Soroush 2008). Manikas and Chang (2009) and Fantahun and Mingyuan(2012)reported that in job shop scheduling problems with sequence-dependent setup times limited research is available. A dispatching rule (scheduling rule/sequencingrule) selects the next job to be processed from the set of jobs awaiting processing in the input queue of a machine. Ramasesh(1990) provides review of simulation research in dynamic job shop scheduling problems. Allahverdiet al.(1999) provides a survey of literature on scheduling problems with setup times/costs. Panwalkaret al. (1977) presented a survey of scheduling rules used in manufacturing systems. Blackstone et al. (1982) presented a survey of scheduling rules used in job shop scheduling problems. Jayamohan and Rajendran(2000) proposed seven dispatching rules for minimizing performance measures such as mean flow time, maximum flow time, variance of flow time and tardiness in dynamic shops. The proposed rules are found to be effective in minimizing different performance measures.Wilbrecht and Prescott (1969) studied the influence of setup times on dynamic job shop scheduling problems. They concluded that job with Smallest Setup Time (SIMSET) rule outperforms other existing scheduling rules. Kim and Bobrowski (1994) studied impact of sequence-dependent setup times on the performance of a dynamic job shop scheduling problems and concluded that setup