Handbook of Advanced Ceramics Machining Episode 6 ppsx

finish parameters R a , R z , and R max were measured after the grinding oper- ations. A mirror finish surface was obtained when ELID grinding was performed with a #4000 mesh-size wheel or finer. Figure 5.32 and Figure 5.33 show a significant improvement in surface finish when grinding using a #4000 mesh wheel compared with #2000 mesh wheel. Better surface finish was obtained with the SRBSN material than Si 3 N 4 , especially when using rougher wheels. However, with finer wheels (#4000) almost the same sur- face finish was obtained with both materials. The results are shown in Figure 5.34 [27]. To produce a mirror surface finish by ELID grinding, a three-step operation was required. The silicon nitride specimens were first ground with a #325 mesh-size wheel. These specimens were further ground TABLE 5.2 Grain Size of Used Diamond Grinding Wheels Mesh Size Grain Size (mm) Average Grain Size (mm) #325 40–90 63.0 #600 20–30 25.5 #1200 8–16 11.6 #2000 5–10 6.88 #4000 2–6 4.06 #6000 1.5–4 3.15 #8000 0.5–3 1.76 Material SRBSN [v = 21.5 m/sec, f = 80 mm/min, t = 1 µm/pass] Wheel: cup type CIFB-D, diameter 200 mm 0.05 0 0 1000 2000 3000 4000 Wheel grit size 5000 6000 7000 8000 0.1 0.02 0.04 0.06 0.08 0.1 0.12 0.2 R z , R max , µm R a , µm 0.3 0.4 0.5 0.25 0.35 0.45 0.55 0.15 R a R max R z FIGURE 5.32 The effect of wheel grit size on surface finish. Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 136 2.10.2006 6:26pm 136 Handbook of Advanced Ceramics Machining with a #600 grit-size wheel and finally ground with a #4000 mesh-size wheel. The mechanism of material removal in ceramic grinding is a combination of microbrittle fracture and micro- or quasiplastic cutting mechanism [28,29]. The quasiplastic cutting mechanism, typically referred R a R z R max R z , R max , µm R a , µm 0.1 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Material silicon nitride Wheel: cup type CIFB-D, diameter 200mm [v = 21.5 m/sec, f = 80 mm/min, t = 1 µm/pass] 0 1000 2000 3000 4000 5000 6000 7000 8000 Wheel grit size FIGURE 5.33 The effect of wheel grit size on surface finish. 0 0 1000 2000 3000 Wheel grit size 4000 5000 6000 7000 8000 0.06 0.05 0.04 R a , µm 0.03 0.02 0.01 Silicon nitride SRBSN (Si 3 N 4 ) Wheel: cup type CIFB-D, diameter 200 mm [v = 21.5 m/sec, f = 80 mm/min, t = 1 µm/pass] FIGURE 5.34 The effect of wheel grit size on surface finish. Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 137 2.10.2006 6:26pm Highly Efficient and Ultraprecision Fabrication of Structural Ceramic Parts 137 to as ductile-mode grinding, results in grooves on the surface that are relatively smooth in appearance. By a careful choice of grinding parameters and control of the process, ceramics can be ground predominantly in this mode [30,31]. On the other hand, the microbrittle fracture mechanism results in surface fracture and fragmentation. Ductile-regime grinding is preferred since no grinding flaws are introduced if the machining is performed in this mode. Surfaces ground in the brittle fracture mode will have significant amounts of surface fragmentation. On the other hand, a surface produced by the ductile mode will contain little or no surface fragmentation. These two modes can be easily differentiated by observing the surfaces under SEM and AFM. 5.4.8.1 SEM and AFM Studies The ground surface topography was analyzed by SEM and AFM to deter- mine the brittle- to ductile-mode transition. The specimens were sputter coated with Au–Pd to enable easier SEM imaging. The brittle fracture portion of the work piece will be represented by a ‘‘white frosted’’ area in the SEM micrograph. Specimens ground with a #325 grit wheel showed a significant white frosted area confirming that the material was predom- inantly removed by brittle fracture. The SEM micrographs also showed that with increasing grit size (finer grain size), the amount of surface fragmentation decreases. When ELID grinding was performed with a #4000 grit-size wheel or a finer, SEM micrographs did not show any surface fragmentation. This shows that under the material is ground in the ductile mode [27]. Ground surfaces were also observed under AFM. The observed surface area was 18 Â 18 mm 2 . The change in surface topography can be observed using AFM. The AFM surface topography also shows that the material was predominantly removed in the ductile mode when ELID grinding was done using a #4000 mesh wheel or finer. The surface finish obtained from the AFM study is presented in Table 5.3 [27]. TABLE 5.3 Surface Roughness of Si 3 N 4 by AFM Wheel Mesh R a (nm) R max (nm) R rms (nm) R z (nm) #325 112.7 1164.7 147.8 832.7 #600 126.5 1533.3 173.3 786.3 #1200 79.54 950.8 108.6 666.0 #2000 41.34 756.5 61.48 456.7 #4000 7.474 334.7 14.34 138.3 #6000 3.734 180.0 5.8 108.3 #8000 3.177 187.9 5.119 102.9 Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 138 2.10.2006 6:26pm 138 Handbook of Advanced Ceramics Machining 5.4.9 Flexural Strength of Silicon Nitride Significant research has been conducted to study the effect of grinding parameters on the strength of ground ceramic specimens. Various investiga- tors have also studied the effect of grinding direction on the strength of ceramics. Figure 5.35 shows the relationship between the annealing tempera- ture and bending strength of alumina ceramics at room temperature. The results show that before annealing specimens ground in the transverse direction have a bending strength 60% lower than that of the specimens ground longitudinally. The bending strength of the specimens ground in the transverse direction increased with the annealing temperature. At about 12008C, the strength was approximately equal to that of the specimens ground in the longitudinal direction [32]. The effects of annealing temperature on the strength of ground silicon nitride specimen have not been studied. Therefore, experiments were conducted to study the effect of annealing and ELID finish grinding on the bending strength of silicon nitride specimens. The material used in the experiment was silicon nitride SN235 manufac- tured by Kyocera. The size of the specimens was 3 Â 10 Â 50. This is the recommended size for the four-point bending test. A large number of Si 3 N 4 specimens were fixed on a plate with wax and mounted on the table of the surface grinding machine. Specimens were ground in longitudinal (PG) and in transverse (TG) direction using a #140 grit-size BB diamond wheel. The following grinding conditions were used: (a) wheel velocity, 1200 m=min, (b) table speed, 20 m=min; (c) traverse pitch, 1 mm, (d) depth of cut, 5 mm, and (e) spark out, 3 passes. The total depth of cut was around 70 mm. 200 300 400 Four-point bending strength, MPa 500 0 200 400 600 800 Annealing temperature, °C Grinding direction Φ = 0° Φ = 90° 1000 1200 1400 1600 Grinding direction FIGURE 5.35 Effects of annealing on four-point bending strength. Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 139 2.10.2006 6:26pm Highly Efficient and Ultraprecision Fabrication of Structural Ceramic Parts 139 Four-point bend tests were performed at room temperature and at 14008C. All bending tests had an upper span of 10 mm and a lower span of 30 mm. An Instron-type universal tester was used for bending tests, with a constant cross head of 0.2 mm=min. Figure 5.36 shows the dimensions and coordinate system of the beam specimen with ground surface in a four-point bend test. Bending test results are presented in Figure 5.37. A significant reduction in bending strength was noticed when specimens were transversely ground compared with those ground longitudinally. PG and TG specimens were annealed at 12008C for 2 h and the bending strength was determined. The strength of the heat-treated TG specimens increased significantly as shown in Figure 5.37 [33]. There was no significant change in the strength of the PG ground specimens after the annealing process. As the TG specimens have the lowest strength, it was decided to study the effect of ELID finish Grinding direction 50 Φ 10 3 10 30 50 FIGURE 5.36 Dimensions and coordinate system of the beam specimen with the ground surface in a four-point test. Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 140 2.10.2006 6:26pm 140 Handbook of Advanced Ceramics Machining grinding on the bending strength of TG ground specimens. These specimens were ground using ELID grinding and a #6000 grit-size (average grain size ¼ 3.15 mm) SD cast iron-bonded wheel. The diameter of the wheel was 150 mm and the width was 10 mm. The following grinding conditions were used: wheel speed, 1200 m=min; table speed, 20 m=min; traverse pitch, 0.6 mm; depth of cut, 0.5 mm; and total depth of cut, 40 mm. The power supply used in the experiment was EPD-10 A, with a capacity of 90 V, 10 A. The following ELID conditions were used: E o ,60V;I p ,10A; on-time and off-time, 2 msec [square wave]. Noritake AFG-M grinding fluid with 2% of water was used in the experiment. The bending strength of the ELID ground specimens was determined (TGE). These ELID ground speci- mens were annealed and the bending strength of these specimens was also determined. The results are presented in Figure 5.37. A significant improve- ment in the bending strength of Si 3 N 4 specimens was achieved when ELID grinding was applied. The bending strength of the specimens was determined at 14008C. The results are presented in Figure 5.38. The max- imum bending strength at the elevated temperature was found with the TGE specimens [33]. Previous investigations have shown that during grinding of ceramics two sets of flaws are introduced. One set is parallel to the grinding direction, 900 PG TG TGH TGE TEHPGH PG PG Parallel ground with #140 SD 740 MPa n—13 SD—90 754 MPa n—3 SD—40 605 MPa n—19 SD—40 730 MPa n—30 SD—62 800 MPa n—5 SD—41 750 MPa n—30 SD—54 TG TG Transverse ground TGH TGH Heat treated after transverse grinding TGE TGE ELID ground with #6000 SD-CIB wheel after transverse grinding TEH TEH Heat treated after ELID grinding PGH PGH Heat treated after parallel grinding 850 800 750 700 MOR at RT, MPa 650 600 550 500 FIGURE 5.37 The effect of ELID grinding on the strength of Si 3 N 4 . Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 141 2.10.2006 6:26pm Highly Efficient and Ultraprecision Fabrication of Structural Ceramic Parts 141 which is fairly elongated, while the second is perpendicular to the grinding direction and smaller in size [34]. This has resulted in a significant reduction in the strength of the silicon nitride ceramic when ground in the transverse direction. As explained earlier, ductile-mode grinding was performed with the application of fine ELID grinding. When TG work pieces were finish ELID ground with a #6000 grit-sized wheel, the grinding mode was ductile. The flaws produced by initial grinding were removed by the fine ELID grinding. The TGE specimens therefore do not contain any significant microcracks. This may be the reason for the significant improvement in the bending strength of the TGE specimens. 5.5 Conclusions In this paper, the application of ELID grinding for effective and precision grinding of various structural ceramic materials is described. ELID techno- logy has been successfully applied for surface grinding using a machining center, a horizontal surface grinder, a vertical rotary surface grinder, and for cylindrical grinding on a turning center. The results are as follows: 1. Compared with conventional grinding, there is a significant reduc- tion in normal grinding force with ELID grinding. Therefore, ELID grinding is recommended for heavy material removal grinding, low- rigidity machines, and low-rigidity work pieces. 750 700 650 600 550 500 450 400 MOR at HT (1400 C), MPa PG TG TGH TGE TEHPGH PG TG TGH TGE TEHPGH 475 MPa SD—36 510 MPa SD—51 670 MPa SD—48 540 MPa SD—60 FIGURE 5.38 The effect of ELID grinding on the strength of Si 3 N 4 (at elevated temperature). Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 142 2.10.2006 6:26pm 142 Handbook of Advanced Ceramics Machining 2. The full potential of ELID grinding, that is, reduced grinding force, can be used only after it has been stabilized. However, the newly proposed modified ELID dressing can provide reduced and almost constant grinding force immediately at the start of grinding. 3. Compared with conventional grinding, a reduction in G-ratio was found when ELID grinding was performed. The G-ratio can be improved by optimizing the ELID current. 4. A mirror surface was achieved on silicon nitride materials when ELID grinding was performed using a #4000 grit-size wheel. The finish ELID technology will find wide application in the optical and semiconductor industries such as mirror finishing of silicon wafers, many kinds of ceramics, ferrite, and glass. 5. SEM and AFM studies reveal that the work piece was pre- dominantly ground in the ductile mode when ELID grinding was performed with a #4000 grit-sized wheel or finer. 6. The bending strength of transversely ground Si 3 N 4 specimens can be improved by annealing at 12008C. 7. A significant improvement in the bending strength of Si 3 N 4 was achieved when finish ELID grinding was performed. 5.6 Acknowledgments The authors express their sincere thanks to the industrial members of the ELID research project for their financial support. Part of the research project was supported by the U.S. Department of Energy. Special thanks to Fuji Die Co. Ltd., Toyko, Japan, for supplying grinding wheels and Ikegami Mold of America and RIKEN authorities for their financial support. The authors also thank Ms. Joyce Medalen for preparing the manuscript. References 1. Jahanmir, S., Ives, L.K., Ruff, A.W., and Peterson, M.B., ‘‘Ceramic Machining: Assessment of Current Practice and Research Needs in the United States,’’ NIST special publication 834, Gaithersburg, MD, 1992. 2. Malkin, S. and Hwang, T.W., ‘‘Grinding Mechanisms for Ceramics,’’ Annals of the CIRP, Vol. 45, No. 2, 1996, pp. 569–580. 3. Nakagawa, T., Suzuki, K., and Uematsu, T., ‘‘Three Dimensional Creep Feed Grinding of Ceramics by Machining Center,’’ Proceedings ASME, WAM, PED, 17, 1985, pp. 1–7. Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 143 2.10.2006 6:26pm Highly Efficient and Ultraprecision Fabrication of Structural Ceramic Parts 143 4. Nakagawa, T. and Suzuki, K., ‘‘Highly Efficient Grinding of Ceramics and Hard Metals on Machining Center,’’ Annals of CIRP, Vol. 35, No. 1, 1986, pp. 205–210. 5. Fuji ELIDer, Catalog from Fuji Die Co. Ltd., Tokyo, Japan, 1996. 6. McGeough, J.A., Principles of Electro Chemical Machining, Chapman and Hall, 1974, pp. 162–195. 7. Welch, E., Yi, Y., and Bifano, T., ‘‘Electro Chemical Dressing of Bronze Bonded Diamond Grinding Wheels,’’ Proceedings of the International Conference on Machin- ing of Advanced Materials, NIST publication 847, 1993, pp. 333–340. 8. NICCO Creep Feed Grinders: Catalog from Carl Citron Inc., NJ. 9. Ohmori, H. and Nakagawa, T., ‘‘Mirror Surface Grinding of Silicon Wafers with Electrolytic In-Process Dressing,’’ Annals of CIRP, Vol. 39, No. 1, 1990, pp. 329–332. 10. Ohmori, H., ‘‘Electrolytic In-Process Dressing (ELID) Grinding Technique for Ultra Precision Mirror Surface Machining,’’ International Journal of JSPE, Vol. 26, No. 4, 1992, pp. 273–278. 11. Ohmori, H. and Takahashi, I., ‘‘Efficient Grinding of Sintered Diamond and CBN Materials Utilizing Electrolytic In-Process Dressing (ELID),’’ Proceedings of the 1st International Abrasive Technology Conference, Seoul, Korea, 1993. 12. Bandyopadhyay, B.P., Ohmori, H., and Takahashi, I, ‘‘Efficient and Stable Grind- ing of Ceramics by Electrolytic In-Process Dressing (ELID),’’ Journal of Materials Processing Technology, Elsevier, Vol. 66, 1997, pp. 18–24. 13. Vickerstaff, T.J., ‘‘Diamond Dressing—Its Effect on Work Surface Roughness,’’ Industrial Diamond Review, Vol. 30, 1970, pp. 260–267. 14. Davis, C.E., ‘‘The Dependence of Grinding Wheel Performance on Dressing Pro- cedure,’’ International Journal ofMachine Tool Design Research, Vol. 14, 1974, pp. 33–52. 15. Konig, W. and Meyen, H.P., ‘‘AE in Grinding and Dressing: Accuracy and Process Reliability,’’ SME, 1990, MR, pp. 90–526. 16. Malkin, S. and Murray, T., ‘‘Mechanics of Rotary Dressing of Grinding Wheels,’’ Journal of Engineering for Industry, ASME, Vol. 100, 1978, pp. 95–102. 17. Koshy, P., Jain, V.K., and Lal, G.K., ‘‘A Model for the Topography of Diamond Grinding Wheels,’’ Wear, Vol. 169, 1993, pp. 237–242. 18. Syoji, K., Zhou, L., and Mitsui, S., ‘‘Studies on Truing and Dressing of Grinding Wheels, 1st Report,’’ Bulletin of the Japan Society of Precision Engineering, Vol. 24, No. 2, 1990, pp. 124–129. 19. Suzuki, K., Uematsu, T., Yanase, T., and Nakagawa, T., ‘‘On-Machine Electro- discharge Truing for Metal Bond Diamond Grinding Wheels for Ceramics,’’ Proceedings of the International Conference on Machining of Advanced Materials, NIST 847, July 1993, pp. 83–88. 20. Wang, X., Ying, B., and Liu, W., ‘‘EDM Dressing of Fine Grain Super Abrasive Grinding Wheel,’’ Journal of Materials Processing Technology, Elsevier, Vol. 62, 1996, pp. 299–302. 21. Piscoty, M.A., Davis, P.J., Saito, T.T., Blaedel, K.L., and Griffith, L., ‘‘Use of In-Process EDM Truing to Generate Complex Contours on Metal Bond Superabrasive Grinding Wheels for Precision Grinding Structural Ceramics,’’ Pro- ceeding of International Conference on Precision Engineering, Taipei, Taiwan, 1997, pp. 559–564. 22. Ohmori, H., Takahashi, I., and Bandyopadhyay, B.P., ‘‘Ultra Precision Grinding of Structural Ceramics by Electrolytic In-Process Dressing (ELID) Grinding,’’ Journal of Materials Processing Technology, Elsevier, Vol. 57, 1996, pp. 272–277. Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 144 2.10.2006 6:26pm 144 Handbook of Advanced Ceramics Machining 23. Ohmori, H., Takahashi, I., and Bandyopadhyay, B.P., ‘‘Highly Efficient Grinding of Ceramic Parts by Electrolytic In-Process Dressing (ELID) Grinding,’’ Materials and Manufacturing Processes, Marcel Dekker, Vol. 11, No. 1, 1996, pp. 31–44. 24. Bandyopadhyay, B.P., Ohmori, H., and Makinouchi, A., ‘‘Efficient and Precision Grinding Characteristics of Structural Ceramics by Electrolytic In-Process Dress- ing (ELID) Grinding,’’ Proceedings of 1998 Japan–U.S.A. Symposium on Flexible Automation, Otsu, Japan, July 1998, pp. 305–311. 25. Bandyopadhyay, B.P., ‘‘Application of Electrolytic In-Process Dressing for High Efficiency Grinding of Ceramic Parts: Research Activities 1995–1996,’’ ORNL=SUB=96-SV716=1 Report, February 1997. 26. Ohmori, H., Takahashi, I., and Bandyopadhyay, B.P., ‘‘Ultra-precision Grinding of Structural Ceramics by Electrolytic In-Process Dressing (ELID) Grinding,’’ Journal of Materials Processing Technology, Elsevier, Vol. 57, 1996, pp. 272–277 27. Bandyopadhyay, B.P., Ohmori, H., and Takahashi, I., ‘‘Ductile Regime Mirror- Finish Grinding of Ceramics with Electrolytic In-Process Dressing (ELID) Grind- ing,’’ Materials and Manufacturing Processes Journal, Marcel Dekker, Vol. 11, No. 5, 1996, pp. 789–802. 28. Inasaki, I., ‘‘High Efficiency Grinding of Advanced Ceramics,’’ Annals of CIRP, Vol. 35, No. 1, 1986, pp. 211–214. 29. Inasaki, I., ‘‘Speed Stroke Grinding of Advanced Ceramics,’’ Annals of CIRP, Vol. 37, No. 1, 1988, pp. 299–302. 30. Ohmori, H. and Nakagawa, T., ‘‘Analysis of Mirror Surface Generation of Hard and Brittle Materials by ELID (Electrolytic In-Process Dressing) Grinding with Superfine Grain Metallic Bond Wheels,’’ Annals of CIRP, Vol. 41, No. 1, 1995, pp. 287–290. 31. Namba, Y., Yamada, Y., Tsuboi, A., Unno, K., and Nakao, H., ‘‘Surface Structure of Mn–Zn Ferrite Single Crystals Ground by an Ultra Precision Surface Grinder with Various Diamond Wheels,’’ Annals of CIRP, Vol. 41, No. 1, 1992, pp. 347–351. 32. Matsuo, Y., Ogasawara, T., Kimura, S., Sato, S., and Yasuda, Y., ‘‘The Effects of Annealing on Surface Machining Damage of Alumina Ceramics,’’ Journal of the Ceramic Society of Japan, (Intl. Edition), Vol. 99, No. 5, 1991, pp. 371–376. 33. Bandyopadhyay, B.P. and Ohmori, H., ‘‘The Effect of ELID Grinding on the Flexural Strength of Silicon Nitride,’’ to be published in the International Journal of Machine Tools and Manufacture, Pergamon press. 34. Rice, R.W. and Mecholowsky, J.J., ‘‘The Nature and Strength Controlling Machining Flaws in Ceramics,’’ Symposium on the Science of Ceramic Machining and Surface Finishing II, NBS Publication 562, 1979, pp. 351–378. Ioan D. Marinescu/Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 145 2.10.2006 6:26pm Highly Efficient and Ultraprecision Fabrication of Structural Ceramic Parts 145 [...]... 164 6. 5.1 Experimental Setup for ELID Grinding of AlN Ceramics 164 6. 5.2 Observation of the ELID Ground Surface 167 6. 5.3 Surface Modifying Effect by ELID Grinding 168 6. 5.4 Analysis of the Modified Surface 174 Acknowledgments 1 76 References 1 76 147 Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 148 6. 10.20 06 2:18am Handbook. .. D Marinescu /Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 1 46 2.10.20 06 6:26pm Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 147 6. 10.20 06 2:18am 6 Electrolytic In-Process Dressing Grinding of Ceramic Materials H Ohmori and K Katahira CONTENTS Abstract 148 Key Words 148 6. 1 Introduction 148 6. 2 ELID Grinding... the ELID technique FIGURE 6. 15 Samples of ZrO2 ferrules produced by ELID centerless grinding Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 160 6. 10.20 06 2:18am Handbook of Advanced Ceramics Machining 160 TABLE 6. 1 ELID Centerless Grinding Results (mm) by Through-Feed for ZrO2 Ferrules #800 Rz Rq #2000 #4000 #8000 0.90 0.040 0. 26 0. 26 0. 066 0.032 0.072 0.054 The... Eo = 60 V, Ip = 10 A, τ on = τ off 5 µ /sec Rotation: 60 0 rpm; electrode: 1 /6 copper; Gap: 0.1 mm 6 80 60 1 4 40 Ew Iw 3 2 20 2 0 0 0 5 10 15 FIGURE 6. 6 Electrical behavior during electrolytic dressing 20 25 30 min Working voltage Ew, V Working current Iw, A 8 Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 154 6. 10.20 06 2:18am Handbook of Advanced Ceramics Machining. .. radius of curvature of the lenses that are produced can be calculated using the following equations: R ¼ Dsi=(2Ã sin a) (for convex lens) (6: 6) R ¼ Dso=(2Ã sin a) (for concave lens) (6: 7) a Nozzle ELID power supply Cup wheel Work piece Electrode FIGURE 6. 16 Schematic of ELID CG-grinding Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 162 6. 10.20 06 2:18am Handbook of. .. number of ZrO2 optical fiber ferrule Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof Electrolytic In-Process Dressing Grinding of Ceramic Materials page 159 6. 10.20 06 2:18am 159 50 nm nm Ra 9 8n Rz Rz 64 2n m, Ry Ra9.8 nm, m, 64 .2 nm, Ry 76. 0 nm 76 0n m ZrO2 #4000 (M (Measured by 2 µm R Diamond stylus evaluated at distance of 1.25 mm) FIGURE 6. 14 Example of surface profile... Ceramics Machining 3837_C0 06 Final Proof page 152 6. 10.20 06 2:18am Handbook of Advanced Ceramics Machining 152 Feed Specific metalbonded wheel Wheel Electro discharge Brush (+ve) Power supply Rotary electrode (−ve) FIGURE 6. 3 Overview of machine setup with electrodischarge truer The ED truing system Feed Wheel FIGURE 6. 4 Overview of machine setup with ED truer Ioan D Marinescu / Handbook of Advanced Ceramics. .. rate of 500 rpm, a feed rate of Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 163 6. 10.20 06 2:18am Electrolytic In-Process Dressing Grinding of Ceramic Materials 113 Surface statistics: Ra: 3. 06 nm µm 163 nm 35 100 Rq: 5.38 nm 20 90 Rz: 80.22 nm 0 Rt: 1 36. 73 nm 80 −20 70 Setup parameters: Size: 368 ϫ 238 60 Sampling: 410.75 nm 50 −40 60 40 Processed options: Terms... higher efficiency and of better surface quality, compared to conventional grinding Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 164 6. 10.20 06 2:18am Handbook of Advanced Ceramics Machining 164 FIGURE 6. 19 ELID ground lens mold Efficient and precise grinding of spherical lens molds with cup wheels using the ELID process was proposed and tested in the present... electrolysis 6. 3 6. 3.1 Efficient and Precision ELID Centerless Grinding of Zirconia Ceramics Experimental Setup for ELID Centerless Grinding of Zirconia Ceramics In this section, microfabrication grinding with ELID centerless grinding is proposed In an experiment, we conducted efficient, high-precision grinding Ioan D Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 1 56 6.10.2006 . effect of wheel grit size on surface finish. Ioan D. Marinescu /Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 1 36 2.10.20 06 6:26pm 1 36 Handbook of Advanced Ceramics Machining with. principle of ELID grinding. Ioan D. Marinescu / Handbook of Advanced Ceramics Machining 3837_C0 06 Final Proof page 150 6. 10.20 06 2:18am 150 Handbook of Advanced Ceramics Machining 6. 2.2 ED Truing. strength of Si 3 N 4 (at elevated temperature). Ioan D. Marinescu /Handbook of Advanced Ceramics Machining 3837_C005 Final Proof page 142 2.10.20 06 6:26pm 142 Handbook of Advanced Ceramics Machining 2.