S-DBR design, implementation and critical evaluation using action research

This research aims to explore and bridge the contradicting views of both academic researchers and practitioners on Simplified Drum-Buffer-Rope (S-DBR). Having evolved from Drum-Buffer-Rope (DBR), S-DBR is the latest Make-To-Order (MTO) Production Planning and Control (PPC) solution introduced by Theory of Constraints (TOC) practitioners. Reviews by academics doubt the suitability of DBR as a PPC in MTO. Instead, Workload Control (WLC) is advocated as the most appropriate PPC application. The appropriateness of S-DBR in generic MTO environment is critically evaluated through theoretical arguments. This is followed by a real-life S-DBR implementation through action research (AR). The purpose is to capture practical knowledge on how S-DBR is reconfigured according to contextual requirements. It is found that previous reviews reduce DBR into a mere bottleneck or constraint rule. This ignores the buffer management concept, a critical concept in TOC applications. This research re-evaluates and advocates S-DBR, together with its three critical concepts: constraints management, buffer management, and load management, as an appropriate PPC in MTO environment. Although both S-DBR and WLC have different origins, they can be represented on a continuum of planning and execution with S-DBR on one end: light planning, heavy execution and WLC on the other end: heavy planning, light execution. The potential incorporation of buffer management in WLC implementation is also proposed and explored. Through AR cycles, an S-DBR solution is successfully redesigned to overcome contextual challenges such as high touch time, wandering bottleneck, and parallel machine route. It has also embedded informal practices, incorporating human roles, and is developed into a decision support system and communication platform. A year after implementation, this solution successfully exposed hidden resources, reduced operation cost by half, and facilitated senior management to empower shop floor personnel, recognising them as an integral part of the intervention solution