Thesis defense of Aitor Lizarralde Aiastui

Thesis defense of Aitor Lizarralde Aiastui

Title of the thesis: "Application of TOC-DBR to Make-To-Order manufacturing contexts: systematic process for bottleneck identification and exploitation based on action research". Obtained the SOBRESALIENTE qualification.

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• Title of the thesis: "Application of TOC-DBR to Make-To-Order manufacturing contexts: systematic process for bottleneck identification and exploitation based on action research"
• Court:
  • President: Dr. D. Jose Pedro Garcia-Sabater
  • Vocal: Dr. D. José Antonio Alfaro Tanco
  • Vocal: Dr. D. Aitor Oyarbide Zubillaga
  • Vocal: Dr. D. Aitor Urzelai Inza
  • Secretary: Dra. Dª. Itxaso Amorrortu Gervasio

Abstract

Drum-buffer-rope (DBR) is a key element of Goldratts theory of constraints (TOC) in which the launch of production orders into the system is controlled according to the schedule of the systems bottleneck. The existing literature has discussed the validity of TOC-DBR as a production planning and control system in make-to-order (MTO) environments, but most studies have taken an analytical approach; real-world empirical cases are scarce. In fact, the literature has recognised that any implementation of production planning and control systems in MTO environments is complex to manage, and this could also be the main cause of the lack of studies on this subject. Additionally, a literature review showed a lack of understanding regarding selecting and exploiting the bottleneck (a crucial part of DBR) in these MTO manufacturing contexts. Therefore, the researcher aimed to provide the following novel guidelines for MTO environments: 1) How to select the bottleneck: The research provided a set of four criteria inspired by the resource-based view and Barneys VRIO concept. 2) How to exploit the bottleneck: Three operative sub-steps to exploit the bottleneck were included; these were partly inspired by a strategic perspective based on the practice-based view. The selection and exploitation of the bottleneck was included in a systematic decision-making process that enabled the operationalisation of the first two steps of Goldratts DBR. This systematic process was developed and tested on four real-world cases using action research (as well as some aspects of constructive research). Given the practical origin of this research, action research was an appropriate methodology since it enabled contributions to academic research while solving real-world problems. The research provided several theoretical contributions (e.g., how to select and exploit the bottleneck in MTO environments) as well as practical contributions (i.e., a systematic process for operationalising the first two steps of TOC-DBR and determining how the company performance could be impacted). Additional (non-expected) contributions also emerged from the research. Among others, a key contribution was related to the different management required by the two types of MTO environments, as follows: Repeat-business customizers (medium product variety and medium volume production): The research showed that exploiting the bottleneck could be a source of better performance; these findings aligned with the practice-based view. Versatile manufacturing companies (high product variety and low volume production): The research showed that approaches based on the resource-based view and practice-based view could improve firms performance. The practice-based view applied to the exploitation of the bottleneck, while the selection of the bottleneck could be determined using the resource-based views VRIO concept (especially concerning resources that were rare and inimitable).