OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 7 No. 2 2025 an enlarged view. Ridge formation marks are observed on the tool flank face. Due to the high hardness of the tungsten carbide drill tool, abrasion wear in the form of ridges is common for cemented carbide tools. Ridge formation is also caused by the rolling of broken hard carbide tool fragments and nano graphene particles in the cutting zone. During MMC drilling, composite particle fragments adhere to the tool forming BUE. Coating was worn away from the substrate during drilling due to abrasion and adhesion wear. Builtup edge formation and abrasion marks are clearly visible on the SEM micrograph along with prominent ridge formation. Conclusions In this experimental investigation, a series of drilling experiments were conducted on MMCs with a PVD-coated tool to study the effects of nano-graphene oxide suspended cutting fluid on thrust force, torque, surface finish, burr height, and circularity. Based on the study, the following conclusions have been drawn: 1. This investigation confirms that environmentally friendly methods, particularly NMQL, can be effectively applied without compromising process results during industrial applications such as drilling MMCs with PVD-coated carbide drills. 2. Graphene oxide nanoparticles mixed with non-edible Undi oil are a viable alternative to conventional cutting fluids in drilling MMCs. 3. NMQL provides better hole quality compared to MQL due to the combined lubricating action of nanoparticles and Undi oil, which effectively enters interface regions and decreases friction between chip and tool-workpiece interface, resulting in smoother sliding and improved circularity. At high cutting speeds, circularity is maximum; at low speeds, circularity is minimum. Similarly, circularity increases as SiC volume fraction increases from 10 to 30 %. 4. Mathematical models describing the relationships between responses and process parameters were developed using RSM. Linear regression models best describe these relationships. 5. Burr height increases sharply as SiC volume fraction changes from 10 to 20 %, then shows a slight decrease at 30 %. 6. Graphene oxide nanofluids, due to their higher thermal conductivity, improve heat transfer and thus provide better surface finish at high cutting speeds compared to MQL. 7. NMQL produces less burr height compared to MQL because high temperatures during MQL increase material ductility, causing greater burr formation. 8. At low cutting speeds, MQL yields better surface finish, while at higher cutting speeds, NMQL performs better due to higher thermal conductivity reducing friction and temperature. 9. Lower torque values are observed during NMQL compared to MQL, attributed to better lubricity from graphene oxide particles. Maximum torque occurs at intermediate cutting speeds. a b Fig. 16. Micrographs of drill tool used in NMQL condition after experimentation
RkJQdWJsaXNoZXIy MTk0ODM1