A study on the importance of selection rules within unbalanced MTO POLCA-controlled production systems

The present paper is aimed at investigating, through simulation, the behaviour of the POLCA method when a Make-to-Order (MTO) production system is highly unbalanced, in terms of both routings and times. In particular, the study is addressed to verify (i) the effective capability of the POLCA method to improve the uncontrolled system and (ii) the impact of how orders are processed at each workstation, to show that POLCA performance can be further improved in such circumstances by adopting an appropriate selection rule. Germs and Riezebos (2010) proved that POLCA is very effective in reducing the Total Throughput Time (TTT) with respect to the corresponding unconstrained production systems. Owing to this, it appears evident that POLCA represents a valuable and effective Make-to-Order (MTO) production control method. However, they only considered balanced systems, hence some observations must be carefully addressed. In fact, often, in real world applications, the systems to be controlled are designed to process units with very different routings, each with significantly different probability to occur.