Mechanism Investigation Of Micro/nanomachining Based On AFM And Development Of Micro/nanomachining System

With the development of the high technology,components which are in micro and nano scales are play an important part in the field of military and commercial use.Nowadays,the micro/nano-machining technology is becoming the focal point of the research.Atomic Force Microscopy(AFM),which is initially intended for observing the surface topography,is now applied for nanomachining.Compared with other methods,AFM-based nanomachining is becoming more prevalent due to its low requirement for extensive processing conditions,operational simplicity,and applicability with a wide range of materials including metals,semiconductors,and polymers.Therefore,a thorough study into the AFM-based nanomachining technology has profound meaning and application value.This dissertation studies two aspects of the AFM-based nanomachining process,including the nanomachining mechanism and the experiment setup.Based on the research of the machining principle,a depth-control theoretical model is proposed and the analytic solution is deduced.Molecular dynamics simulation is adopted to study the mechanism of the nanomachining process.The main focus is on the water-lubricated nanomachining and the investigation of the minimum feed.Then,a nanomachining system based on the optical lever principle is designed and fabricated.Experiments are carried out to verify the validity of the system,and the effects of machining parameters are studied as well.The main research contents and achievements are listed as follows:In order to solve the control problem during the nanomachining,a depth-control model is studied for the AFM-based nanomachining process.Strain gradient elastic theory and strain gradient plastic theory are adopted separately for describing the scale effect of the cantilever and the deformation of the sample.These two theories are combined by Hamilton principle.The relationship between machining force and the groove depth are obtained.The accuracy of the theoretical model is verified by experiments.Meanwhile,the values derived by our theoretical model and by the macro cantilever theory are compared.The results shows that our model is more reliable and accurate than the other methods.The mechanism of nanomachining is investigated by Molecular dynamics simulations.The main focus of our study is on the water-lubricated nanomachining process.The effects of the water-layer thickness,machining depth,and velocity on the surface topography,machining forces,coefficient of friction and the temperature are investigated.MD simulations are also adopted for the judgment of the minimum feed.The effects of the machining depth,tip angles,and tip shape on the minimum feed are also studied.A high performance nanomachining system is developed based on the optical level principle.Considering the optical path and the interfere,the prototype has compact structure,high stiffness,and well operability.In the motion control system,the macro-motion is realized by the slide-table,aiming at lifting the tip and placing samples.Micro-motion is realized by PZT actuated flexure hinges.Vision system is adopted for the laser alignment.A marble framework is designed and dimensional optimized for fixing the structure and improving the stiffness.The control system is developed by the LabVIEW software.Finally,a micro-motion stage for calibration is designed.The static and dynamic characteristics are studied by ANSYS.Calibration tests are carried out for accurate detection and controlling of machining forces.1D and 2D patterns are machined by the machining system and the validity of the experiment setup is verified by the experiments.In addition,machining parameters such as forces,machining velocity,feed,water-layer,and the machining times on the machining process are also investigated by experiments.The comparison is also made between experiments and MD simulation results.The similarity and diversity between the two analytical method are also demonstrated.