The National Research Institute of Mechanical Engineering plans to organize an Institute-level Doctoral Thesis Evaluation Council for doctoral candidate Nguyen Van Tung in early May 2025. The Institute publishes information on the doctoral thesis of the candidate as follows:

Full name of doctoral candidate: Nguyen Van Tung

Scientific supervisors: Prof. Dr. Vu Ngoc Pi and Dr. Phan Dang Phong

Major: Mechanical Engineering - Code: 9520103

Training institution: National Research Institute of Mechanical Engineering - Ministry of Industry and Trade

Thesis title: “Research on the influence of some technological parameters on the outer cylindrical surface EDM process using graphite electrode with powder-mixed dielectric fluid”

Summary of new conclusions of the thesis

1. Scientific significance:

- The thesis contributes to clarifying the relationship among the main machining parameters of PMEDM including C_p, T_on, T_off, I_p and SV for the single-objective problem (surface roughness, material removal rate, and electrode wear rate) and the multi-objective problem, while simultaneously proposing reasonable pulse regimes for machining 90CrSi steel using a graphite electrode.

-  This research contributes to supplementing a solid theoretical foundation for further studies on EDM and PMEDM technology.

2. Practical significance

- The results of the thesis can be directly applied in production to machine complex-shaped parts such as punches and dies using the PMEDM method, improving product quality and predicting values to optimize the machining process to minimize production costs.

- In addition, the research results of the thesis can be used as materials for further research and teaching in the specialized field of EDM and PMEDM machining.

3. New contributions of the thesis

The research results can be used for the development of EDM technology and especially the PMEDM method. The outstanding new points of the research include:

- Successfully utilized the PMEDM process using a graphite electrode to machine the outer surface of shaped cylindrical parts made of 90CrSi material with a dielectric fluid mixed with SiC powder.

- Investigated the influence of main input technological parameters including powder concentration, pulse-on time, pulse-off time, pulse current, and pulse voltage on the output parameters of the PMEDM process such as surface roughness, material removal rate, and electrode wear rate. In addition, optimal pulse regimes for single-objective functions including minimum surface roughness, maximum material removal rate, and minimum electrode wear rate have been proposed.

- Solved the multi-objective optimization problem with the aforementioned single-objective functions using two methods: the Taguchi method combined with grey relational analysis and multi-criteria decision-making methods including TOPSIS, MABAC, and EAMR combined with two weight determination methods Entropy and MEREC. Thereby, optimal pulse regimes corresponding to each method are proposed. Furthermore, the application scope of the optimal results of each method is also provided.

Detailed information of the doctoral thesis of candidate Nguyen Van Tung can be viewed at here