Analysis of material flow in a job shop with assembly operations

Facing competitive pressure from both domestic and foreign sources, today’s manufacturers must strive to keep delivery promises and reduce inventory. This depends largely on a manufacturer’s ability to predict job flowtimes reliably, hence allowing the assignment of accurate and attainable due-dates. An approximation method is presented to estimate the mean and standard deviation of job flowtimes in a dynamic job shop with assembly operations. The accuracy of the method for predicting the flowtimes of jobs with varying structural complexities is assessed through computer simulation. While in general it is more accurate for jobs with simpler structure, the simulation results indicate that, over a range of test conditions, the approximation method is both simple and effective for estimating job flowtimes in assembly shops.