Integrating Quality and Quantity Modelling in a Production Line

This paper investigates the behavior of automated production lines subject to quality inspection. Machines are unreliable and can fail for different reasons: operational failures stop the machine without involving quality issues; quality failures lead machines to produce defective parts without stopping. We analyze a 2-machine-1-buffer line where machines are modelled by Markov chains with discrete states and separated by a buffer of finite capacity. Using such models, we analyze how production system design, quality, and productivity are interrelated in production systems. We show how inventory capacity can influence system yield and productivity. The approach considers control charts, buffers of finite capacity and a delay in quality information due to remote inspection. Numerical results and comparisons with simulation are reported.