Experimental Study On Rotary Surface Part Of Zirconia Ceramic By Polished Fluid Magnetic Abrasive

Zirconia(ZrO₂)ceramics have excellent properties such as high melting point,high hardness,high chemical stability,wear resistance,large elastic modulus and low dielectric constant.They have been widely used in aerospace,precision machinery,military industry,biomedicine and other fields.With the development of these new fields,the requirements for surface quality and dimensional accuracy of zirconia parts are getting higher and higher.In harsh working environment,subsurface damage and other defects will greatly reduce the service life of parts.The traditional processing methods of zirconia ceramics mainly include diamond grinding wheel grinding,free abrasive grinding and other auxiliary processing methods.Due to the high hardness and brittleness of zirconia ceramics,it is easy to produce micro cracks,sub surface damage and other defects when these methods are used improperly.Fluid magnetic abrasives(FMA)finishing technology,as a flexible precision machining method,has the advantages of strong shape adaptability,good heat dissipation performance and high processing quality.The normal force acting on the workpiece surface in the process of machining is low,which is not easy to cause micro cracks and sub surface damage.Therefore,we put forward the idea of surface finishing of zirconia ceramic parts by using Fluid Magnetic Abrasives.Based on the contact mechanics,tribology,electromagnetism,hydrodynamics and other theories,the processing mechanism and material removal mechanism of zirconia ceramic parts are studied.The influence of process parameters on the processing effect is studied by designing single factor experiments.The surface roughness model is established based on Taguchi method The process parameters were optimized by NSGA-II algorithm.The project was supported by the National Natural Science Foundation of China(51075294),the Natural Science Foundation of Shanxi Province(201601D011060),the Open Project of the Key Laboratory of Precision and Special Processing of the Ministry of Education(JMTZ201603),Key Research and Development Project of Shanxi Province(201903D121091).The main research contents of this paper are as follows:(1)Based on the domain theory and field dipole moment theory,the rheological properties of the Fluid Magnetic Abrasives are studied.The mechanical and motion behaviors of the abrasive particles in the Fluid Magnetic Abrasives are analyzed.The processing principle and the micro material removal mechanism of the Fluid Magnetic Abrasives are studied.On this basis,the macro-scale processing mechanism of the rotating surface parts of the zirconia ceramic is established The material removal model is used to analyze the main process parameters which affect the finishing effect of zirconia rotary surface parts,such as abrasive particle size,abrasive type,magnetic induction strength,workpiece speed,axial motion speed,processing time,etc.(2)Based on the analysis of the properties of zirconia ceramic materials and the effects of various components of Fluid Magnetic Abrasives,the Fluid Magnetic Abrasives suitable for zirconia ceramic processing were prepared.A Fluid Magnetic Abrasives processing device for zirconia ceramic rotary surface parts was built.A single factor experiment was designed to study the influence of different process parameters on the surface roughness and material removal rate by testing the surface roughness,quality and surface morphology of the samples before and after processing.(3)Based on Taguchi method,a three factor and three-level orthogonal experiment of zirconia ceramic processing was established with magnetic induction,workpiece speed and composite motion speed as variables.Through variance analysis of the test results,the significance level of each process parameter was obtained.The order of significance of process parameters affecting surface roughness is: axial movement speed > magnetic induction intensity > workpiece speed;the order of significance of process parameters affecting material removal rate is: workpiece speed > magnetic induction intensity > axial movement speed.Taking the above three process parameters as variables,the prediction models of surface roughness Ra and material removal rate MRR were established by multiple regression analysis.(4)Based on the prediction model,the optimization objective function was established to minimize the surface roughness Ra and maximize the material removal rate MRR.Based on the non-dominance with the elite strategy Sorting genetic algorithm(NSGA-II),Python programming was used to solve the model and the Pareto optimal solution set was obtained.In the optimal solution set,3 sets of parameters were randomly selected for experimental verification.And the experimental results shew that the error between the experimental value and the predicted value is within 10%.It proved that the optimization model is feasible.