The student Aitor Orue Irasuegui obtained an EXCELLENT grade

The student Aitor Orue Irasuegui obtained an EXCELLENT grade

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• Thesis title: Application of TOC-DBR to Make-To-Order manufacturing scenarios: systematic process for subordination of non-bottleneck resources to the bottleneck

Court:

• Presidency: Javier Santos García (Universidad de Navarra)
• Vocal: Alberto de la Calle Vicente (Universidad de Deusto)
• Vocal: Victoria Rodríguez Chacón (Universidad de Navarra)
• Vocal: Gorka Unzueta Aranguren (Mondragon Unibertsitatea)
• Secretary: Myriam Soto Ruiz de Gordoa (Mondragon Unibertsitatea)

Abstract:

Today’s industrial companies are faced with increasing complexity due to rapid technological developments, shorter product life cycles and globalisation. In this new and changing environment, companies must be able to quickly adapt, and many have had to migrate from a make-to-stock (MTS) environment to a make-to-order (MTO) environment.

According to some studies (Chakravorty, 2001; Darlington et al., 2015; Modi et al., 2019; Riezebos et al., 2003), the theory of constraints (TOC) and its drum-buffer-rope (DBR) production planning and control system (PPCS) has been shown to be a valid methodology for responding to the problems of MTO environments. However, other studies (Atwater & Chakravorty, 2002; Pretorius, 2014; Wu & Yeh, 2006) have detected difficulties in implementing TOC-DBR. To overcome some of these issues, Lizarralde (2020) has developed a systematic decision-making process to apply DBR in MTO scenarios, proposing a change in the first two steps of the TOC methodology. This doctoral thesis was born with the aim of completing the systematic process of implementing the TOC-DBR methodology in MTO environments.

In the theoretical framework, no article has investigated the systematisation of the third step of the TOC methodology. After a systematic literature review of the TOC-DBR methodology, it becomes evident that two factors, protective capacity and protective inventory, play a key role in absorbing system variability when implementing the third step of the methodology. Furthermore, to design the systematic implementation process of the third step, a specific literature review has been conducted in the field of tactical and strategic processes to integrate the strategic vision of the organisation into the TOC-DBR operational model.

As a result, the researcher has developed three novel implementation phases to apply to MTO environments:

1. Model configuration phase
2. Operational model phase
3. Tactical Sales and Operations (S&OP) phase

These three phases have been included in a systematic implementation process, which enables the implementation of the third step of Goldratts TOC methodology. This systematic process has been developed through four case studies (CSs) based on two companies in the Basque Country with different MTO scenarios. For this purpose, this thesis employs a sequential mixed methods approach using a holistic, multiple-CS approach. This design is a research approach that involves the use of qualitative and quantitative methods in sequential order.

As a result of our research, four theoretical contributions have been made. For example, some of the contributions has been to analyse the impact of protective capacity on the application of step three of TOC-DBR in MTS and MTO environments or defining the level of protective capacity as a strategic factor or decision for organisations operating in MTO environments. On the other hand, a practical contribution has also been made that integrate the monitoring and management of the level of protective capacity in the TOC-DBR methodology via the concept of capacity buffer used in the DDAE model.

Interestingly, another unexpected practical contribution has also emerged throughout the research process. This key contribution relates to the need to integrate the operational phase with the strategic phase in the systematic process and is presented as follows:

Creation and description of the systematic process of implementing the third step of the TOC-DBR methodology for MTO environments integrating the S&OP process via the DDAE model. This integration combines two complementary methodologies: the TOC-DBR model and DDAE model.