Doctoral Dissertations

Keywords and Phrases

Cutting forces; Nanofluid; Surface integrity; Sustainable manufacturing; Thermal conductivity; Viscosity


"Extreme heat and friction are generated in machining difficult-to-cut metals used in aerospace and nuclear industries leading to poor machinability (high cutting forces, rapid tool wear, shorter tool life, and poor surface integrity). Conventional flood coolant (CEC) used in industry is environmentally unfriendly, hazardous to operators, and unsustainable. These problems motivated this research, which can be mitigated with the use of effective biodegradable cutting fluids, appropriate cutting conditions, and lubrication/cooling strategies. This research provides a sustainable and environmentally friendly replacement to CEC. Firstly, the research characterized three vegetable oils (High Oleic Soybean Oil (HOSO), Low Oleic Soybean Oil (LOSO), and Accu-lube Lb2000) and studied their rheological and thermal properties at varying temperatures (25 – 70 °C) compared to CEC. The result showed that the viscosity of all vegetable oils decreases exponentially with temperature and is significantly higher than that of CEC. HOSO gave the highest viscosity enhancement of 4688.30% compared to CEC at 30 °C. Secondly, using CEC to determine optimal cutting parameters. The optimized cutting speed, 40 m/min, and down milling were used to evaluate the machinability of Inconel 718 under the HOSO-MQL at varying oil flow rates. The results show that flow rate at 70 ml/h and air pressure of 4.14 bar gave the longest tool life comparable to that of CEF-CS and improves machinability by providing enough thin lubrication film. Finally, due to the low thermal conductivity of vegetable-based oil, further investigations were conducted to enhance the viscosity and thermal conductivity of HOSO using 3-different nanoparticles of 30 nm size at varying wt.% concentration. The result shows an enhancement of viscosity by 11.5% and thermal conductivity by 55% of HOSO Nanofluid"--Abstract, p. iv


Okafor, A. Chukwujekwu

Committee Member(s)

Dharani, Lokeswarappa R.
Chandrashekhara, K.
Park, Jonghyun
Okoronkwo. Monday


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


Missouri University of Science and Technology

Publication Date

Spring 2022


xv, 128 pages

Note about bibliography

Includes_bibliographical_references_(pages 29, 61, 93, 122)


© 2022 Theodore Obumselu Nwoguh, All Rights Reserved

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 12219