A comparative study of line design approaches for serial production systems

Over the past decade two approaches, just‐in‐time (JIT) and theory of constraints (TOC), for designing and operating production lines have developed, each claiming to be the “correct” way. In addition there are still those who maintain that line balanced (whenever possible) is the optimal method. This study uses simulation to compare each of these approaches for designing and operating production lines under various levels of processing time variability, station downtime, and total system inventory. Not surprisingly, the JIT approach appears to work best when system variability is low. The TOC approach works best when system variability is high. This shows that lines designed using TOC principles perform significantly better than JIT lines when inventory is low, and JIT lines perform significantly better than TOC lines as inventory is added to the system. The traditionally balanced line did not perform best under any of the conditions used in this study.