A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1979

This study describes a model for' seeking an optimal solution to N x M job shop scheduling problems in which each job has a number of operations to be performed on the specified machines in an order which may not be the same for all jobs . The model is formulated in the General Purpose Simulation System V(GPSSV) language. It can handle conditions where: (a) an operation can be performed on more than one group (a group may consist of more than one unit) of machines or stand by machines, (b) a machine set-up is needed before a specific operation, (c) a machine breakdown happens during an operation, (d) an operation can be started before finishing preceding operation (start lag), provided that the preceding operation finishes earlier (stop-lag). The model is comprehensive and flexible enough to take care of: (a) different dispatching rules; (b) probabilistic processing, set-up; and machine repair times; and (c) cases when there is no order received for a specific job. Gantt chart as graphical representation and tables of the results from the model are obtained using FORTRAN subroutines. A simple 4 x 3 job shop problem is solved to verify the model under different conditions. A case study of a manufacturing firm is conducted in order to illustrate practical applicability of the model.