Study Of Damage In The Silicon Nitride Ceramics Spherical Surface Precise Grinding

With the excellent mechanical and themal properties, Silicon nitride ceramics isbecoming popular materials in industrial fields. Currently, ultraprecise processing onsilicon nitride materials mainly achieved by superhard abrasive precision grinding andpolishing, but due to the large grinding resistance, parts are easy to produce grindingdamage. Grinding damage can reduce the intensity of the work piece and effect surfacequality. So in order to control the generation and expansion of grinding damage, it isnecessary to set up a forecasting model about the material properties and grindingparameters.The domestic and overseas research development of the surface/subsurfacedamage in ceramic grinding was reviewed, analyzed and discussed, and the theory andexperiment of the surface/subsurface damage in ceramic grinding have been studied inthis paper．The current research efforts related to the grinding induced damage of ceramicsmainly focus on the theoretical, experimental and numerical simulation. In this paper,defining the surface fragmentation damage rate of materialDs as the damage index ofthe surface damage and the depth of surface/subsurface crack damage as the indexof the surface/subsurface crack damage. The models of the surface fragmentationdamage rate and the depth of surface/subsurface crack damage were establisted.The spherical parts grinding experiment was conducted on the NC precisiongrinder MK2945C. The grinding surface morphplogy was observed by metallographicmicroscope. The experiment for the surface fragmentation damage was carried byMATLAB, and then values of the surface fragmentation damage rate were receivedthrough this experiment. A nano-polishing machine (Nanopoli-100) was used for thesurface/subsurface crack damage experiment, in order to obtain the depth ofsurface/subsurface crack damage, a circular cross-section polishing method wasdesigned.The damage experiment results for silicon nitride ceramic spherical grinding wasanalyzed. Through regression analysis of experiment results, parameter of model wasdetermined. Through the experiment, the validity of the model was verified.Through using these models, according to the given grinding parameters thegrinding surface/subsurface damage of silicon nitride spherical can be predicted andmanipulated. Thereby we can optimize the silicon nitride ceramic spherical grindingprocess, increase the productivity and reduce the silicon nitride ceramics spherical processing costs and the grinding damage.