Characterizing and Mitigating Small-Diameter Tool Wear in Nickel-Based Superalloy Machining

Abstract

This thesis investigates tool failure in the micromachining of single-crystalline René N4 turbine blades coated with ceramic thermal barrier layers. The work done in this thesis was promoted through a partnership between Massachusetts Institute of Technology (MIT) and GE Vernova. This thesis is complemented by the thesis written by Luke Placzek. Together these works offer a comprehensive case study in process analysis and manufacturing optimization. This thesis begins with groundwork to document tool failure mechanisms and frequencies through photographic analysis. This was done alongside a study of historical data to analyze tool breakage frequency in the context of the turbine blade. Based on these insights, an Analysis of Variance (ANOVA) test followed by a Tukey’s Honestly Significant Difference (HSD) test identified statistically significant differences in tool breakage rates across machines and rows. A detailed study of tool wear progression was conducted to better understand how small-diameter endmills wear when machining the nickel-based superalloy René N4. Utilizing all these findings, an updated tool path was created to optimize tool life This work lays the foundation for an improved machining strategy to reduce tool breakage in manufacturing turbine blades. Estimations show that the refined CAM strategies may reduce tool breakage by roughly 33 percent. Preliminary models estimate the implementation of the suggested improvements will save GE Vernova 2.5 million dollars per year.