Study On Crack Damage And Cutting Performance Of Chemical Vapor Deposition Diamond Coated Micro-tool

In recent years,microfabrication technology has been widely applied in biology,medicine,and aerospace domain.The performance of micro cutting tools is one of the important factors that restrict the development of this technology.Chemical vapor deposition diamond micro tool has attracted much attention because of its excellent cutting performance and good economic efficiency.In the present study,it is found that the tool failure is easy to occur in the proces s of machining,but the mechanism of damage failure is not clear,as well as lacking specific researches on the factors which affect its cutting performance.Therefore,XFEM is used to analyze the crack damage pattern of CVD diamond in this paper.The numerical simulation of the force and crack propagation during the milling process is carried out.Through the micro milling experiments,the damage and failure forms of the tool are summarized.Furthermore,the effect of different technology parameters on cutting performance is discussed.The research content of this paper is of great significance to further clarify the crack damage mechanism of CVD diamond micro tools and to improve the quality of micro machining.Firstly,the damage and failure of CVD diamond under various crack modes are studied based on XFEM,and the influence of different model parameters on SIFS during the propagation of single pre-existing crack is analyzed.And then a model of CVD diamond containing defects is established.With this mod el the evolution process of crack from initiation to propagation until the coat sheds is simulated,from which three typical damage forms of cracks due to the interaction of material defects are summarized.By adding micro cracks in the CVD diamond model,the competition and coupling mechanism in the process of multi-crack growth is discussed,which further clarifies the crack damage mechanism of CVD diamond.Secondly,the micro machining process is simulated by establishing the micro milling simulation model of CVD diamond micro tool,during which the surface topography of the workpiece is simulated and three directional cutting forces are extracted.Based on the data of cutting force obtained by simulation,the numerical simulation of crack damage on CVD diamond micro milling tool is carried out.In addition,the stress distribution is calculated and the form of tool damage is analyzed.And then the influence of different simulation parameters on workpiece shape,cutting force and tool damage is studied.Consequently,the theoretical guidance can be provided for the micro milling experiment of cutting tool performance.Finally,the micro milling experiments with CVD diamond micro tool on TC4 are carried out,through which a variety of damage and failure form s during cutting process are studied and the phenomena and causes of crack damage are analyzed emphatically.And through single factor experiment,the cutting force and the surface quality of the workpiece are analyzed.Furthermore,the effects of spindle speed,feed rate and milling depth on cutting performance are studied.As a result,the reasonable combination of technology parameters is determined and the simulation results are verified.