The polishing process of advanced ceramic balls using a novel eccentric lapping machine
Abstract The finishing process of advanced ceramic balls can be divided into two steps. The first step is lapping in which most of the stock from the ball is removed at a higher material removal rate. The second step is polishing in which the required ball surface roughness, roundness, and dimensional and geometric accuracy are achieved. In polishing, the abrasive particle size is 1 μm, and the load and speed are lower than lapping. A novel eccentric lapping machine is used for polishing hot isostatically pressed (HIPed) silicon nitride balls. In the initial polishing stage, the polishing load is demonstrated as being most influential in the reduction of surface roughness value Ra. However, in the later polishing stages, the erosive process played a major role in the further reduction of Ra, although the high roughness peaks cannot be removed by erosive process alone. Experimental results also show that, in order to achieve desired surface roughness value, the initial surface quality of the upper plate should be reasonably high, and deep scratches on the ball surface from previous lapping processes should be avoided. The best polishing results achieved were surface roughness values of Ra of 0.003 μm and r.m.s. (Rq) of 0.004 μm, ball roundness of 0.08–0.09 μm. This proves that the novel eccentric lapping machine is also suitable for polishing advanced ceramic balls.
Effect of Various Parameters on Spread in Flashing Operation of Precision Steel Ball Manufacturing Process
Precision balls are the key elements for critical aeronautical bearings, guidance system balls for space and military applications, precision valves, automotive bearings and other applications. In all these applications higher precision is required. Hence, the development of a more economical finishing method becomes a critical problem in the application of advanced Steel ball manufacturing. Spread is the variation in the Diameter of Balls of same batch or lot. Spread is a very critical quality parameter which must be controlled while operation. The experiment for Flashing was designed using a full factorial design with two levels for each input variable (2k factorial design). Since there are three factors, each at two levels, the design is 23 factorial designs. Factors taken for the experiments are Pressure between two plates, No. of Grooves in plates & RPM of Ring Plate. From the main effect plot pressure should be at lower level. Same way from RPM should be at lower level & No. of grooves should also be at lower level to achieve minimum spread. Also at these level of the parameters the residual (error) found from the regression model is -0.625 which is very less so the value of these parameters satisfying the required function. Also from the experiments Percentage contribution are pressure having 43.55%, No. of Grooves having 23.31% & RPM having 23.31% effect on spread.
Kant's 'Religion within the Boundaries of Mere Reason'
Preface 1. Context 2. Overview of Themes 3. Reading the Text Prefaces to the First and Second Editions Part I of the Religion Part II of the Religion Part III of the Religion Part IV of the Religion 4. Reception and Influence 5. Guide for Further Reading Bibliography Index