Research On Material Properties And Evaluation Method Of Machined Surface For High Precision Ceramic Balls

Ceramic ball bearings are widely used in industrial fields and it also keep the development in the direction of high performance and high precision. As a result of this, higher requirements for its material properties and surface quality are put forward. But now the evaluation system of material properties and the quality of machining surface for high precision ceramic balls is not perfect. So it’s necessary to do more research on ceramic balls’ material properties and surface quality.High precision ceramic balls generally refer to balls whose accuracy level above the G5grade. The main object of the research mentioned above is silicon nitride ceramic balls. Its main parameters and corresponding testing method are studied. The evaluation criterion of ceramic balls’material properties and surface quality is also established here. Base on this, the parameters like density, porosity, hardness, fracture toughness and crush load were tested. After analyzing the results we found that the hardness of blank balls is higher than the precision balls, but the hardness in the surface of precision balls is more stable than the blank balls. In addition, although the crush load of ceramic balls is lower than steel balls which are in the same size, but the ceramic balls do has equal bearing capacity with steel balls under the condition of same contact stress.In order to explore the influence to the quality of machined surface of grinding pressure, abrasive particle size and grinding time, experimental study was made singly. Meanwhile, a deep study about surface defects of ceramic balls was also made. Some of these defects are produced in the making process of blank balls, others are produced in subsequent machining process. Their existence would have adverse effect for ball’s performance and life.The evaluation methods of ceramic balls including microscopic observation method, roughness measuring method, vibration testing method and image processing method based on image segmentation are studied here. Compared to microscopic observation method and surface roughness measurement method, vibration testing method is a more comprehensive evaluation method. Image processing method is a new method and it is considered to have a very good development prospect.