Information on the doctoral thesis of PhD candidate Nguyen Manh Cuong (revised version after the Institute-level Thesis Evaluation Council):

Full name of PhD candidate: Nguyen Manh Cuong

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

Discipline: 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 perfecting knowledge on the powder-mixed electrical discharge machining (PMEDM) process, especially knowledge on PMEDM of parts with shaped cylindrical profiles. Specifically:

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

- Developed predictive formulas for surface roughness, material removal rate, and electrode wear rate under appropriate PMEDM parameters.

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

2. Practical significance

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

3. New contributions of the thesis

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

- The study evaluated the influence of several technological parameters in the EDM process on surface roughness, material removal rate, and electrode wear when machining the outer cylindrical surface of hardened 90CrSi material using SiC-powder-mixed dielectric fluid with a copper electrode.

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

- Developed empirical formulas to predict surface roughness, optimal material removal rate, and electrode wear rate under appropriate PMEDM parameters.

- Solved the multi-objective optimization problem of technological parameters for EDM of outer cylindrical surfaces 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.

For detailed thesis information, see here