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Electrochemical micromachining using flat electrolyte jet
CIRP Annals - Manufacturing Technology 60 (2011) 251–254
Contents lists available at ScienceDirect
CIRP Annals - Manufacturing Technology jou rnal homep age : ht t p: // ees .e lse vi er. com/ci rp/ def a ult . asp
Electrochemical micromachining using flat electrolyte jet M. Kunieda (1)a,*, K. Mizugai a, S. Watanabe b, N. Shibuya b, N. Iwamoto c a b c
Department of Precision Engineering, The University of Tokyo, Tokyo, Japan Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan Japan Fine Steel Co., Ltd., Yamaguchi, Japan
A R T I C L E I N F O
A B S T R A C T
Keywords: Electrochemical machining Micromachining Electrolyte jet
This paper describes the development of a novel machining method capable of micro-milling and electrochemical turning using a flat electrolyte jet. The workpiece is machined locally in the area hit by the jet which moves when an electrical current is applied to it. Use of a flat jet in place of a cylindrical jet improves milling speed, and turning process is realized by the flat jet hitting the surface of the rotating cylindrical workpiece. Since depth of cut can be determined by the electrical current or dwelling time of the jet on the surface, there is no need for precise positioning of the nozzle against the workpiece. ß 2011 CIRP.
1. Introduction In electrolyte jet machining [1,2], a workpiece is machined only in the area hit by the jet when an electrical current is applied to it. By scanning the jet on the workpiece, intricate patterns can be fabricated without the use of a special mask [3] because the distribution of current density is localized under the jet [4,5]. Since electrolyte jet machining is an electrochemical process, there are no burrs, cracks, nor heat-affected zones generated on the machined surface. Use of a focused laser beam directed into the jet stream was found to further enhance the material removal rate [6,7]. This process can be used not only for removing processes by anodic dissolution, but also for coloring process by anodic oxidation [8]. Even three-dimensional (3D) shapes can be machined by controlling the current and dwelling time of the jet over the workpiece [9]. Furthermore, by reversing the polarity, selective electroplating [10] and 3D additive manufacturing [11] can be performed. In these processes however, the need to scan the cylindrical jet results in longer machining time than normal electrochemical machining using shaped electrodes and photofabrication using masks. In this study, we therefore conducted electrolyte jet machining using a flat electrolyte jet capable of machining grooves with similar shapes to the cross section of the jet without the need to scan the cylindrical jet. We applied these flat jets to the micro-texturing of flat surfaces and micro-turning of rods with high aspect ratio and complicated shapes. 2. Electrolyte jet machining 2.1. Principle of electrolyte jet machining Electrolyte jet machining is carried out by jetting electrolytic aqueous solution from a nozzle over the workpiece while applying voltage between the nozzle and workpiece as shown in Fig. 1. When the electrolyte jet hits the workpiece at a sufficiently high velocity,
* Corresponding author. 0007-8506/$ – see front matter ß 2011 CIRP. doi:10.1016/j.cirp.2011.03.022
the solution flows radially outward in a fast thin layer and suddenly increases in thickness. Only when this hydraulic jump is observed, electrolytic dissolution is limited to the area hit by the jet because distribution of the current density can be concentrated in this area [5]. 2.2. Experimental equipment Fig. 2 shows the experimental setup. The workpiece was set on a table which was placed in a work sink to drain the electrolyte. The position of the work tank was controlled horizontally using an XY table. The nozzle was installed on the Z table to adjust the gap width between the nozzle and workpiece. The electrolyte was supplied from the pressure tank pressurized by an air compressor. The polarity of the nozzle was negative, and the pulse width and peak value of the machining current were controlled synchronously with the positioning control of the XY table. The distribution of machined depth under the jet is basically determined by the current density distribution in the area hit by the jet. However, with the electrolyte which can generate passive films, dissolution is prevented by the oxide film which is easily formed in areas with low current density. Hence, workpieces can be machined more preferentially under the jet. For this reason, in this study we used a sodium nitrate aqueous solution of 20 wt%, with which passive films can be formed. 2.3. Flat jet In electrolyte jet machining, the maximum current density is limited to about 200 A/cm2 [3]. With micromachining, the diameter of the cylindrical jet cannot be increased. We therefore developed a new flat jet as shown in Fig. 3 to increase the material removal rate. Under the same current density, groove machining time can be reduced inversely proportional to the width of the flat jet. Another advantage of flat jet is that nozzle clogging can be avoided because of the larger cross section area of the internal flow, whereas clogging is a serious problem especially when the nozzle diameter is small in the case of round nozzles. The groove in Fig. 3 was machined on a stainless steel plate using a slit nozzle of 1926 mm 41 mm, with a gap width of 1 mm, tank pressure of
[()TD$FIG]
M. Kunieda et al. / CIRP Annals - Manufacturing Technology 60 (2011) 251–254
252
conditions as those in Fig. 3. Higher gap voltage and higher tank pressure led to higher current density, resulting in higher material removal rate. Although the current density was proportional to the gap voltage, the material removal rate was saturated, indicating that current efficiency decreases when current density is significantly high.
[()TD$FIG]
3.2. Jet quality
Fig. 1. Principle of electrolyte jet machining.
The cross section of the jet was found to become round in the downstream due to surface tension of liquid, thus deteriorating the jet quality. When the gap width was too short, the gap was filled with the electrolyte, disabling hydraulic jump. Hence, influences of the gap width and tank pressure on the length and width of grooves were investigated as shown in Fig. 5. The width of groove was obtained from the area without the rounded ends. The dotted lines indicate the length and width of the nozzle slit. When the gap width was short, the groove length was nearly equal to that of the opening of the slit nozzle. However, the length decreased and the width increased with increasing gap width. We therefore investigated the influence of tank pressure at the gap width of 3 mm, and found that higher tank pressures are effective for maintaining good parallelism of jet.
[()TD$FIG]
3.3. Expanding jet
Fig. 2. Experimental equipment.
To realize micromachining, the slit width should be decreased, but this can cause clogging problems. Hence, we proposed using a flat jet with expanding throat nozzle as shown in Fig. 6. Since this jet can expand in the plane parallel to the slit length, the thickness of the jet decreases in the flow direction, thereby realizing a flat jet with thickness thinner than the slit width. Fig. 7 shows grooves machined using the expanding jet with increasing gap width. The groove length peaks at the gap width of 6–7 mm. Further increase in the gap width resulted in decrease of the groove length because the width of the flat jet decreased due to surface tension. The deformation of the jet caused by surface tension can be observed from the photo shown in Fig. 6. It is considered that the grooves can be machined more straight by improving the flatness and roughness of the inner surface of the slit nozzle. 3.4. Application to surface texturing
Fig. 3. Groove machining using flat jet.
0.3 MPa, current of 25 mA, and machining time of 0.1 s. We found both ends of the groove to be rounded, most likely because the cross section of the jet was deformed due to surface tension.
Using a straight slit nozzle with opening size of 2290 mm 20 mm, non-electrolysis nickel plated surface was textured as shown in Fig. 8. The jet was first scanned at the speed of 0.25 mm/s with sinusoidal current of 50 mA in amplitude and 2 Hz in frequency. Then the second scanning was conducted in the direction perpendicular to the first one.
3. Machining characteristics 4. Electrolyte jet turning (EJT) 3.1. Material removal rate 4.1. Principle Fig. 4 shows the influence of gap voltage and tank pressure on current density and volume removal rate when grooves were machined on a stainless steel plate using the same machining [()TD$FIG]
Turning process is realized when the surface of the rotating cylindrical workpiece is hit by the electrolyte jet, as shown in Fig. 9.
Fig. 4. Influence of gap voltage and tank pressure on current density and material removal rate (slit size: 1926 mm 41 mm, gap width: 1 mm).
[()TD$FIG]
[()TD$FIG]
M. Kunieda et al. / CIRP Annals - Manufacturing Technology 60 (2011) 251–254
253
Fig. 8. Surface texturing using flat jet (sinusoidal current 0–50 mA with frequency of 2 Hz).
[()TD$FIG]
Fig. 5. Influence of gap width and tank pressure on groove shape (slit size: 1923 mm 43 mm, current: 25 mA).
[()TD$FIG]
Fig. 9. Electrolyte jet turning (EJT) using flat jet.
[()TD$FIG] Fig. 6. Expanding throat nozzle.
Since material removal volume is proportional to electric charge according to Faraday’s law, depth of cut can be determined by either electric current or dwelling time of the jet on the surface. For this reason, there is no need to control the gap width. In addition, initial positioning of the tool against the workpiece is also not necessary, which has always been a difficult problem in micromachining using conventional processes such as cutting and grinding. The use of jets wider than the workpiece diameter enables significantly quick machining compared to cylindrical jets since the flat jet can hit the circumference at the same time. Positioning errors of the slit nozzle relative to the workpiece in the direction perpendicular to the workpiece axis do not affect machining accuracy. 4.2. Grooving, cutting-off and face turning Ring grooves were machined on the circumference of copper wires. Fig. 10 shows photos of grooves obtained changing the working time with the current of 50 mA. The width of the grooves was found to remain constant regardless of the depth of cut. When the working time was 5.5 s, the copper wire cut-off as shown in Fig. 11. A protrusion was left at the center of the copper wire, because current density was not uniform in the thickness direction of the jet. Hence, flat end surfaces could not be obtained from the cutting-off process only. Owing to this, after the cutting-off process, the end surface was finished by feeding the workpiece [()TD$FIG]
Fig. 7. Grooves machined using expanding jet (slit opening: 2032 mm 37 mm, tank pressure: 0.5 MPa, current: 10 mA, machining time: 20 s, stainless steel).
Fig. 10. Relation between working time and groove shape (slit size: 2000 mm 40 mm, gap width: 1.5 mm, tank pressure: 0.5 MPa, current: 50 mA, workpiece: Cu 1 0.3 mm, revolution: 2500 rpm).
axially in the direction normal to the plane surface of the jet, with the feed speed of 0.2 mm/min and feed length of 100 mm. As shown in Fig. 11, the protruded part was removed and the end surface was fabricated evenly. Fig. 12 compares the groove width between the straight jet and expanding jet. Thinner groove widths could be obtained using the expanding jet because the thickness of the expanding jet is smaller than that of the straight jet. 4.3. Longitudinal turning and profiling As shown in Fig. 13, longitudinal turning was carried out by
()TD$FIG][moving the jet along the axial direction of the copper workpiece
Fig. 11. Cutting-off and face turning.
[()TD$FIG]
254
M. Kunieda et al. / CIRP Annals - Manufacturing Technology 60 (2011) 251–254
that the rough surface resulted from inhomogeneous microstructure and impurities of the copper workpiece. 5. Conclusions
Fig. 12. Effect of expanding jet (slit size: 2000 mm 40 mm, gap width: 5.0 mm, tank pressure: 0.5 MPa, current: 15 mA, working time: 10 s).
[()TD$FIG]
A novel electrolyte jet machining process using a flat jet was developed. Use of the flat jet increases the machining speed without sacrificing the micromachining capability. Texturing of plane surfaces and electrolyte jet turning processes such as grooving, cutting-off, facing, and profiling were successfully carried out with just a simple setup and dimension control. By synchronizing the machining current with the scanning motion of the jet, complicated shapes could be fabricated without the need to control the plunging depth. The expanding flat jet was found to be more useful for miniaturization than the straight jet because jet thickness thinner than the slit width can be obtained without a clogging problem. The small process force and zero-tool wear of this method are additional advantages for generating complicated micro patterns in metallic sheets and rods with better dimensional accuracy than conventional processes. Acknowledgements
[()TD$FIG]
Fig. 13. Longitudinal turning.
This work was supported by the New Energy and Industrial Technology Development Organization (NEDO), Grant for Practical Application of University R & D Results under the Matching Fund Method, 2007.9–2010.3.
References
Fig. 14. Longitudinal turning with sinusoidal current.
with the feed speed of 6 mm/min. After performing roughmachining three times at a constant current of 50 mA, the rod was finished at the current of 25 mA. After this, final finishing was carried out at the current of 10 mA to obtain the rod diameter of 1 60 mm. The total working time was 60 s. Since changing the current synchronized with the axial feed enables fabricating various profiles without the need to control the tool position in the radial direction, we were able to carry out profiling using a sinusoidal current waveform. The current was changed sinusoidally between 0 mA and 50 mA when the jet was transferred from the tip of the workpiece to the base. Fig. 14 shows the results of repeating this machining step five times. It is noted
[1] Ippolito R, Tornincasa S, Capello G (1981) Electron-Jet Drilling. Annals of the CIRP 30(1):87–89. [2] Kozak J (1989) Some Aspects of Electro Jet Drilling. 4th International Conference on Developments in Production Engineering Design & Control, 363–369. [3] Kunieda M, Yoshida M, Yoshida H, Akamatsu Y (1993) Influence of Micro Indents Formed by Electro-chemical Jet Machining on Rolling Bearing Fatigue Life. ASME PED 64:693–699. [4] Kozak J, Rajukar KP, Balkrishna R (1996) Study of Electrochemical Jet Machining Process. Transactions of the ASME—Journal of Manufacturing Sciences and Engineering 118(4):490–498. [5] Yoneda K, Kunieda M (1996) Numerical Analysis of Cross Section Shape of Micro-Indents Formed by the Electrochemical Jet Machining. Journal of JSEME 29(63):1–8. (in Japanese). [6] Datta M, Romankiw LT, Vigliotti DR, von Gutfeld RJ (1989) Jet and Laserjet Electrochemical Micromachining of Nickel and Steel. Journal of Electrochemical Society 136(8):2251–2256. [7] De Silva AKM, Pajak PT, Harrison DK, McGeough JA (2004) Modelling and Experimental Investigation of Laser Assisted Jet Electrochemical Machining. Annals of the CIRP 53(1):179–182. [8] Mori Y, Kunieda M (1997) Maskless Coloring of Titanium Alloy using Electrolyte Jet. Proceedings of JSEME Annual Meeting in 1997, 13–16. (in Japanese). [9] Natsu W, Ooshiro S, Kunieda M (2008) Research on Generation of Threedimensional Surface with Micro-electrolyte Jet Machining. CIRP Journal of Manufacturing Science and Technology 1:27–34. [10] Alkire RC, Chen TJ (1982) High-Speed Selective Electroplating with Single Circular Jets. Journal of Electrochemical Society 129(11):2424–2432. [11] Kunieda M, Katoh R, Mori Y (1998) Rapid Prototyping by Selective Electro Deposition using Electrolyte Jet. Annals of the CIRP 47(1):161–164.
Contents lists available at ScienceDirect
CIRP Annals - Manufacturing Technology jou rnal homep age : ht t p: // ees .e lse vi er. com/ci rp/ def a ult . asp
Electrochemical micromachining using flat electrolyte jet M. Kunieda (1)a,*, K. Mizugai a, S. Watanabe b, N. Shibuya b, N. Iwamoto c a b c
Department of Precision Engineering, The University of Tokyo, Tokyo, Japan Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan Japan Fine Steel Co., Ltd., Yamaguchi, Japan
A R T I C L E I N F O
A B S T R A C T
Keywords: Electrochemical machining Micromachining Electrolyte jet
This paper describes the development of a novel machining method capable of micro-milling and electrochemical turning using a flat electrolyte jet. The workpiece is machined locally in the area hit by the jet which moves when an electrical current is applied to it. Use of a flat jet in place of a cylindrical jet improves milling speed, and turning process is realized by the flat jet hitting the surface of the rotating cylindrical workpiece. Since depth of cut can be determined by the electrical current or dwelling time of the jet on the surface, there is no need for precise positioning of the nozzle against the workpiece. ß 2011 CIRP.
1. Introduction In electrolyte jet machining [1,2], a workpiece is machined only in the area hit by the jet when an electrical current is applied to it. By scanning the jet on the workpiece, intricate patterns can be fabricated without the use of a special mask [3] because the distribution of current density is localized under the jet [4,5]. Since electrolyte jet machining is an electrochemical process, there are no burrs, cracks, nor heat-affected zones generated on the machined surface. Use of a focused laser beam directed into the jet stream was found to further enhance the material removal rate [6,7]. This process can be used not only for removing processes by anodic dissolution, but also for coloring process by anodic oxidation [8]. Even three-dimensional (3D) shapes can be machined by controlling the current and dwelling time of the jet over the workpiece [9]. Furthermore, by reversing the polarity, selective electroplating [10] and 3D additive manufacturing [11] can be performed. In these processes however, the need to scan the cylindrical jet results in longer machining time than normal electrochemical machining using shaped electrodes and photofabrication using masks. In this study, we therefore conducted electrolyte jet machining using a flat electrolyte jet capable of machining grooves with similar shapes to the cross section of the jet without the need to scan the cylindrical jet. We applied these flat jets to the micro-texturing of flat surfaces and micro-turning of rods with high aspect ratio and complicated shapes. 2. Electrolyte jet machining 2.1. Principle of electrolyte jet machining Electrolyte jet machining is carried out by jetting electrolytic aqueous solution from a nozzle over the workpiece while applying voltage between the nozzle and workpiece as shown in Fig. 1. When the electrolyte jet hits the workpiece at a sufficiently high velocity,
* Corresponding author. 0007-8506/$ – see front matter ß 2011 CIRP. doi:10.1016/j.cirp.2011.03.022
the solution flows radially outward in a fast thin layer and suddenly increases in thickness. Only when this hydraulic jump is observed, electrolytic dissolution is limited to the area hit by the jet because distribution of the current density can be concentrated in this area [5]. 2.2. Experimental equipment Fig. 2 shows the experimental setup. The workpiece was set on a table which was placed in a work sink to drain the electrolyte. The position of the work tank was controlled horizontally using an XY table. The nozzle was installed on the Z table to adjust the gap width between the nozzle and workpiece. The electrolyte was supplied from the pressure tank pressurized by an air compressor. The polarity of the nozzle was negative, and the pulse width and peak value of the machining current were controlled synchronously with the positioning control of the XY table. The distribution of machined depth under the jet is basically determined by the current density distribution in the area hit by the jet. However, with the electrolyte which can generate passive films, dissolution is prevented by the oxide film which is easily formed in areas with low current density. Hence, workpieces can be machined more preferentially under the jet. For this reason, in this study we used a sodium nitrate aqueous solution of 20 wt%, with which passive films can be formed. 2.3. Flat jet In electrolyte jet machining, the maximum current density is limited to about 200 A/cm2 [3]. With micromachining, the diameter of the cylindrical jet cannot be increased. We therefore developed a new flat jet as shown in Fig. 3 to increase the material removal rate. Under the same current density, groove machining time can be reduced inversely proportional to the width of the flat jet. Another advantage of flat jet is that nozzle clogging can be avoided because of the larger cross section area of the internal flow, whereas clogging is a serious problem especially when the nozzle diameter is small in the case of round nozzles. The groove in Fig. 3 was machined on a stainless steel plate using a slit nozzle of 1926 mm 41 mm, with a gap width of 1 mm, tank pressure of
[()TD$FIG]
M. Kunieda et al. / CIRP Annals - Manufacturing Technology 60 (2011) 251–254
252
conditions as those in Fig. 3. Higher gap voltage and higher tank pressure led to higher current density, resulting in higher material removal rate. Although the current density was proportional to the gap voltage, the material removal rate was saturated, indicating that current efficiency decreases when current density is significantly high.
[()TD$FIG]
3.2. Jet quality
Fig. 1. Principle of electrolyte jet machining.
The cross section of the jet was found to become round in the downstream due to surface tension of liquid, thus deteriorating the jet quality. When the gap width was too short, the gap was filled with the electrolyte, disabling hydraulic jump. Hence, influences of the gap width and tank pressure on the length and width of grooves were investigated as shown in Fig. 5. The width of groove was obtained from the area without the rounded ends. The dotted lines indicate the length and width of the nozzle slit. When the gap width was short, the groove length was nearly equal to that of the opening of the slit nozzle. However, the length decreased and the width increased with increasing gap width. We therefore investigated the influence of tank pressure at the gap width of 3 mm, and found that higher tank pressures are effective for maintaining good parallelism of jet.
[()TD$FIG]
3.3. Expanding jet
Fig. 2. Experimental equipment.
To realize micromachining, the slit width should be decreased, but this can cause clogging problems. Hence, we proposed using a flat jet with expanding throat nozzle as shown in Fig. 6. Since this jet can expand in the plane parallel to the slit length, the thickness of the jet decreases in the flow direction, thereby realizing a flat jet with thickness thinner than the slit width. Fig. 7 shows grooves machined using the expanding jet with increasing gap width. The groove length peaks at the gap width of 6–7 mm. Further increase in the gap width resulted in decrease of the groove length because the width of the flat jet decreased due to surface tension. The deformation of the jet caused by surface tension can be observed from the photo shown in Fig. 6. It is considered that the grooves can be machined more straight by improving the flatness and roughness of the inner surface of the slit nozzle. 3.4. Application to surface texturing
Fig. 3. Groove machining using flat jet.
0.3 MPa, current of 25 mA, and machining time of 0.1 s. We found both ends of the groove to be rounded, most likely because the cross section of the jet was deformed due to surface tension.
Using a straight slit nozzle with opening size of 2290 mm 20 mm, non-electrolysis nickel plated surface was textured as shown in Fig. 8. The jet was first scanned at the speed of 0.25 mm/s with sinusoidal current of 50 mA in amplitude and 2 Hz in frequency. Then the second scanning was conducted in the direction perpendicular to the first one.
3. Machining characteristics 4. Electrolyte jet turning (EJT) 3.1. Material removal rate 4.1. Principle Fig. 4 shows the influence of gap voltage and tank pressure on current density and volume removal rate when grooves were machined on a stainless steel plate using the same machining [()TD$FIG]
Turning process is realized when the surface of the rotating cylindrical workpiece is hit by the electrolyte jet, as shown in Fig. 9.
Fig. 4. Influence of gap voltage and tank pressure on current density and material removal rate (slit size: 1926 mm 41 mm, gap width: 1 mm).
[()TD$FIG]
[()TD$FIG]
M. Kunieda et al. / CIRP Annals - Manufacturing Technology 60 (2011) 251–254
253
Fig. 8. Surface texturing using flat jet (sinusoidal current 0–50 mA with frequency of 2 Hz).
[()TD$FIG]
Fig. 5. Influence of gap width and tank pressure on groove shape (slit size: 1923 mm 43 mm, current: 25 mA).
[()TD$FIG]
Fig. 9. Electrolyte jet turning (EJT) using flat jet.
[()TD$FIG] Fig. 6. Expanding throat nozzle.
Since material removal volume is proportional to electric charge according to Faraday’s law, depth of cut can be determined by either electric current or dwelling time of the jet on the surface. For this reason, there is no need to control the gap width. In addition, initial positioning of the tool against the workpiece is also not necessary, which has always been a difficult problem in micromachining using conventional processes such as cutting and grinding. The use of jets wider than the workpiece diameter enables significantly quick machining compared to cylindrical jets since the flat jet can hit the circumference at the same time. Positioning errors of the slit nozzle relative to the workpiece in the direction perpendicular to the workpiece axis do not affect machining accuracy. 4.2. Grooving, cutting-off and face turning Ring grooves were machined on the circumference of copper wires. Fig. 10 shows photos of grooves obtained changing the working time with the current of 50 mA. The width of the grooves was found to remain constant regardless of the depth of cut. When the working time was 5.5 s, the copper wire cut-off as shown in Fig. 11. A protrusion was left at the center of the copper wire, because current density was not uniform in the thickness direction of the jet. Hence, flat end surfaces could not be obtained from the cutting-off process only. Owing to this, after the cutting-off process, the end surface was finished by feeding the workpiece [()TD$FIG]
Fig. 7. Grooves machined using expanding jet (slit opening: 2032 mm 37 mm, tank pressure: 0.5 MPa, current: 10 mA, machining time: 20 s, stainless steel).
Fig. 10. Relation between working time and groove shape (slit size: 2000 mm 40 mm, gap width: 1.5 mm, tank pressure: 0.5 MPa, current: 50 mA, workpiece: Cu 1 0.3 mm, revolution: 2500 rpm).
axially in the direction normal to the plane surface of the jet, with the feed speed of 0.2 mm/min and feed length of 100 mm. As shown in Fig. 11, the protruded part was removed and the end surface was fabricated evenly. Fig. 12 compares the groove width between the straight jet and expanding jet. Thinner groove widths could be obtained using the expanding jet because the thickness of the expanding jet is smaller than that of the straight jet. 4.3. Longitudinal turning and profiling As shown in Fig. 13, longitudinal turning was carried out by
()TD$FIG][moving the jet along the axial direction of the copper workpiece
Fig. 11. Cutting-off and face turning.
[()TD$FIG]
254
M. Kunieda et al. / CIRP Annals - Manufacturing Technology 60 (2011) 251–254
that the rough surface resulted from inhomogeneous microstructure and impurities of the copper workpiece. 5. Conclusions
Fig. 12. Effect of expanding jet (slit size: 2000 mm 40 mm, gap width: 5.0 mm, tank pressure: 0.5 MPa, current: 15 mA, working time: 10 s).
[()TD$FIG]
A novel electrolyte jet machining process using a flat jet was developed. Use of the flat jet increases the machining speed without sacrificing the micromachining capability. Texturing of plane surfaces and electrolyte jet turning processes such as grooving, cutting-off, facing, and profiling were successfully carried out with just a simple setup and dimension control. By synchronizing the machining current with the scanning motion of the jet, complicated shapes could be fabricated without the need to control the plunging depth. The expanding flat jet was found to be more useful for miniaturization than the straight jet because jet thickness thinner than the slit width can be obtained without a clogging problem. The small process force and zero-tool wear of this method are additional advantages for generating complicated micro patterns in metallic sheets and rods with better dimensional accuracy than conventional processes. Acknowledgements
[()TD$FIG]
Fig. 13. Longitudinal turning.
This work was supported by the New Energy and Industrial Technology Development Organization (NEDO), Grant for Practical Application of University R & D Results under the Matching Fund Method, 2007.9–2010.3.
References
Fig. 14. Longitudinal turning with sinusoidal current.
with the feed speed of 6 mm/min. After performing roughmachining three times at a constant current of 50 mA, the rod was finished at the current of 25 mA. After this, final finishing was carried out at the current of 10 mA to obtain the rod diameter of 1 60 mm. The total working time was 60 s. Since changing the current synchronized with the axial feed enables fabricating various profiles without the need to control the tool position in the radial direction, we were able to carry out profiling using a sinusoidal current waveform. The current was changed sinusoidally between 0 mA and 50 mA when the jet was transferred from the tip of the workpiece to the base. Fig. 14 shows the results of repeating this machining step five times. It is noted
[1] Ippolito R, Tornincasa S, Capello G (1981) Electron-Jet Drilling. Annals of the CIRP 30(1):87–89. [2] Kozak J (1989) Some Aspects of Electro Jet Drilling. 4th International Conference on Developments in Production Engineering Design & Control, 363–369. [3] Kunieda M, Yoshida M, Yoshida H, Akamatsu Y (1993) Influence of Micro Indents Formed by Electro-chemical Jet Machining on Rolling Bearing Fatigue Life. ASME PED 64:693–699. [4] Kozak J, Rajukar KP, Balkrishna R (1996) Study of Electrochemical Jet Machining Process. Transactions of the ASME—Journal of Manufacturing Sciences and Engineering 118(4):490–498. [5] Yoneda K, Kunieda M (1996) Numerical Analysis of Cross Section Shape of Micro-Indents Formed by the Electrochemical Jet Machining. Journal of JSEME 29(63):1–8. (in Japanese). [6] Datta M, Romankiw LT, Vigliotti DR, von Gutfeld RJ (1989) Jet and Laserjet Electrochemical Micromachining of Nickel and Steel. Journal of Electrochemical Society 136(8):2251–2256. [7] De Silva AKM, Pajak PT, Harrison DK, McGeough JA (2004) Modelling and Experimental Investigation of Laser Assisted Jet Electrochemical Machining. Annals of the CIRP 53(1):179–182. [8] Mori Y, Kunieda M (1997) Maskless Coloring of Titanium Alloy using Electrolyte Jet. Proceedings of JSEME Annual Meeting in 1997, 13–16. (in Japanese). [9] Natsu W, Ooshiro S, Kunieda M (2008) Research on Generation of Threedimensional Surface with Micro-electrolyte Jet Machining. CIRP Journal of Manufacturing Science and Technology 1:27–34. [10] Alkire RC, Chen TJ (1982) High-Speed Selective Electroplating with Single Circular Jets. Journal of Electrochemical Society 129(11):2424–2432. [11] Kunieda M, Katoh R, Mori Y (1998) Rapid Prototyping by Selective Electro Deposition using Electrolyte Jet. Annals of the CIRP 47(1):161–164.