Abstract. This collaborative research work will study the feasibility of vibration assisted target specific nanoscale machining of brittle material. The goal of the research is to generate fundamental knowledge of nano ultrasonic machining process by conducting rigorous analytical and experimental investigations to understand the mechanism of material removal, the range of machinable feature sizes, effect of machining parameters on the productivity of the machined feature, and the uncertainty and sustainability of the nano ultrasonic machining process. A commercial atomic force microscope (AFM) will be used in this exploratory research as an experimental platform to perform ultrasonic nano abrasive machining, as well as nano measurement. The scope of the research includes a process model formulation to predict the material removal, based on appropriate set of process parameters. The scientific barriers such as lack of knowledge base of ductile and brittle mode erosion at nano scale models, and technical barriers such as behavior of abrasive powder at ultrasonic frequency and nanoscale, form the main risks of this study. However, if successful, this project will lead to a new and very effective process for the accurate nano scale machining of brittle materials used in electronic, medical, automotive and aviation industries.
Success of this research is expected to have a transformative effect on the target specific nanomachinability of a wide variety of both conductive and nonconductive materials. Potential applications include high precision DNA detection devices, interconnects nano packaging, and low cost mask correction for electronics manufacturing. Results of this study may serve as prelude to abrasive based picofinishing technology. Outcome of this project will be synergized with our other nano machining activities to educate graduate and undergraduate students in manufacturing courses offered at University of Cincinnati and University of Nebraska-Lincoln. This experience will be used to nurture training and learning within underrepresented minorities and to augment the ongoing partnership with area school community. The results of this research will be disseminated through peer-reviewed publications, presentations and university?s websites, short courses at professional society meetings and reports to NSF.
The major goal of this project is to enable vibration assisted target specific nano abrasive machining process. The research objective of this project is to test the hypothesis that target specific nanoscale machining will occur in a vibrating brittle material when a nano tool is pushed on it in a nano diamond abrasive medium. An atomic force microscope (AFM) was used in this exploratory research as an experimental platform to perform vibration assisted nano abrasive machining, as well as nano measurement. Nano-cavities with circular shape having depths (in the range of 6-64 nm) and diameters (in the range of 78-276 nm) were machined. Additionally, patterns of nano-cavities were successfully machined to verify the controllability and repeatability aspect of the process. Material removal mechanism was studied using molecular dynamics simulation (MDS) method and a material removal mechanism map has been created. Varying loss of energy of the abrasive grain in the presence of liquid medium and non-uniform size and shape of the abrasive particles were initially identified to cause process uncertainty. Further studies using molecular dynamics revealed that the movement of the nanodiamond grain is significantly affected by the liquid medium resulting in an energy loss in the range of 25-32% of the initial energy supplied by the tool. A mathematical model has been developed to predict the material removal rate and the model has been experimentally validated. Additionally a preliminary investigation of bone machining by micro roatary ultasonic machining (micro-RUM) was conducted to determine its feasibilty of avoiding cellular necrosis. the effectt of ifferent machining conditions such as working fluid, static load and rotational speed on the performance of micro-RUM is studied. It was found that bovine milk as a working fluid results into better productivity, better surface quality and less tool wear. Three graduate students have been trained by the PI (Murali Sundaram) at the University of Cincinnati on molecular dynamics simulation, mathematical modeling and operating the AFM. Ms. Anne Brant, a pre-junior female student in Mechanical Engineering received research experiences for undergraduates in Fall 2013. One graduate student (experiments, simulation software and analysis) and one undergraduate student (literature review) were partially supported under this project by the PI (K.P. Rajurkar) at the University of Nebraska-Lincoln. Outcome of this project is being used for curriculum development to educate graduate and undergraduate students in "Micro and Nanomanufacturing"- a dual level course and "Advanced Manufacturing processes" a graduate course taught by Prof. Sundaram at the University of Cincinnati (UC). Similarly, project results and developments are being taught in one graduate course "Advanced Manufacturing processes " and one undergraduate/graduate course on Machining Processes by Prof. Rajurkar at the University of Nebraska-Lincoln. The results of this research are being disseminated through peer-reviewed publications, conference piublications. presentations, and reports to NSF.
