The National Research Institute of Mechanical Engineering plans to organize the Institute-level PhD thesis evaluation committee for doctoral candidate (NCS) Nguyen Manh Cuong in November 2023. The Institute posts information about the doctoral candidate's PhD thesis as follows:

Full name of doctoral candidate: Nguyen Manh Cuong

Supervisors: Assoc. Prof. Dr. Vu Ngoc Pi and Assoc. Prof. Dr. Le Thu Quy

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 electrical discharge machining process of outer cylindrical surface of 90CrSi steel with SiC nano-powder mixed dielectric fluid”

Summary of new conclusions of the thesis

1. Scientific significance:

The thesis has contributed to further improving the knowledge of the powder-mixed electrical discharge machining (PMEDM) process, especially the knowledge about PMEDM of parts with shaped cylindrical profiles. Specifically:

- Clarifying the influence of technological parameters (voltage, discharge current, pulse on time, pulse off time, powder concentration) on surface roughness, material removal rate, and electrode wear rate when machining the cylindrical surface of hardened 90CrSi steel with SiC nano-powder in the dielectric fluid.

- Providing prediction formulas for surface roughness, material removal rate, and electrode wear rate under appropriate PMEDM pulse parameters.

- Evaluating the effectiveness of PMEDM using SiC nano-powder and copper electrode for machining parts with shaped cylindrical profiles.

2. Practical significance

The research successfully applied PMEDM method for machining small-sized parts with shaped cylindrical profiles using SiC nano-powder and copper electrode. The results can be directly applied to mechanical manufacturing facilities when machining products such as tablet press punches (or sheet metal stamping punches) with shaped cylindrical profiles to improve process efficiency. Additionally, the thesis results can be used as reference material for scientific studies on the PMEDM process.

3. New contributions of the thesis

- Successfully applied the PMEDM method for machining small-sized parts with shaped cylindrical profiles using SiC nano-powder and copper electrode.

- The study evaluated the influence of some technological parameters during electrical discharge machining on surface roughness, material removal rate, and electrode wear rate when machining the outer cylindrical surface of hardened 90CrSi steel using dielectric fluid mixed with SiC powder and copper pulse electrode.

- Solved single-objective optimization problems to determine the optimal set of technological parameters for PMEDM, including powder concentration, pulse on time, pulse off time, current intensity, and voltage when machining the outer cylindrical surface to achieve the following objectives: minimum surface roughness, maximum material removal rate, and minimum electrode wear rate.

- Developed experimental formulas to predict values of surface roughness, optimal material removal rate, and electrode wear rate during PMEDM under appropriate technological conditions.

- Solved the multi-objective optimization problem of technological parameters when machining the outer cylindrical surface of hardened 90CrSi steel with SiC nano-powder mixed dielectric fluid by applying the Taguchi method and grey relational analysis with three single-objective functions: minimum surface roughness, maximum material removal rate, and minimum electrode wear rate.

Detailed content of the PhD thesis of NCS Nguyen Manh Cuong is available at here