SUMMARY
Grinding is an abrasive machining process used for the final shaping of components that require very smooth surfaces and a high dimensional accuracy. In recent years, the costs of grinding operations have increased with a greater demand for high-strength, low-weight superalloy components. Titanium and nickel-based alloys are desirable for their high creep-rupture strength and corrosion and oxidation resistance in high temperature environments. However, they are very difficult to grind due to a combination of poor thermal properties, rapid work-hardening, and a high level of chemical reactivity. In this thesis, two methods are investigated to improve performance in plunge centerless grinding of Inconel 718 and Ti-6Al-4V superalloy fasteners: (1) economic optimization of grinding parameters and (2) reduced quantity lubrication using a fluid enhanced with graphite nanoparticle additives. In the first part, a systematic approach is presented for finding the optimum parameters in two stages: (i) modeling of relationships among key input variables and output responses using Taguchi’s Design of Experiments and statistical regression and (ii) determination of optimum conditions in the feasible operating region defined by process constraint boundaries using machining economics theory. The optimum parameters yield an appreciable productivity increase, reducing the current cycle times by an average of 21% and 13% for Inconel 718 and Ti-6Al-4V, respectively. In the second part, grinding performance is evaluated under graphite-enhanced fluid application to assess its potential for replacing the traditional flood cooling method. Results show that the application of a graphite-enhanced fluid at a reduced flow rate is more effective than flood cooling in reducing material removal energy levels and wheel wear rates in the grinding process.