The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and...The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and low working gap was investigated by the Grey-Taguchi method.The influences of peak current,pulse on-time,pulse off-time and spark gap on electrode wear（EW）,material removal rate（MRR） and working gap（WG） in the micro milling electrical discharge machining of Inconel 718 were analyzed.The experimental results show that the electrode wear decreases from 5.6×10-9 to 5.2×10-9 mm3/min,the material removal rate increases from 0.47×10-8 to 1.68×10-8 mm3/min,and the working gap decreases from 1.27 to 1.19 μm under optimal micro milling electrical discharge machining process parameters.Hence,it is clearly shown that multiple performance characteristics can be improved by using the Grey-Taguchi method.展开更多
Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial c...Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes （ACEs） are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye （ACE） with surface roughness （Ra） below 0.12 p.m is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.展开更多
Based on microscope and image processing, a new method of auto tool setting for micro milling was presented. Firstly, a realtime image of tool setting area was obtained by microscope and CCD camera, then image process...Based on microscope and image processing, a new method of auto tool setting for micro milling was presented. Firstly, a realtime image of tool setting area was obtained by microscope and CCD camera, then image processing was carried out on this image and the gap between the tool and workpiece was calculated. The gap measurement was sent to motion controlling card to make the tool approach to the surface of workpiece. These steps were repeated until the gap is zero, which means that tool setting was finished. Moreover, a reliability verification test was conducted. Results indicated that the precision of tool setting is satisfactory.展开更多
Micro milling has many advantages in fabricating three-dimensional(3D) structure in micrometer scale. The micro milling machine tool with high positioning accuracy is of great importance for getting micro structure wi...Micro milling has many advantages in fabricating three-dimensional(3D) structure in micrometer scale. The micro milling machine tool with high positioning accuracy is of great importance for getting micro structure with high profile precision and good surface quality. Meanwhile, the method of position error compensation is a good way to improve the accuracy of the micro milling machine tools. In this paper,a software method is adopted to compensate the positioning error and improve the positioning accuracy. According to error cancellation theory,the compensation values are generated and compensation tables are built to adjust the positioning error in the NC system based on Industrial Motion and Automation Control( IMAC). The positioning accuracy of linear motor is ± 0. 3 μm without backlash after compensation. In order to verify the effectiveness of compensation on the machining performance,concave spherical surfaces are processed on the micro milling machine tool. The experimental results show that the profile radius error of the spherical surface machined with compensation decreases more than 60%.展开更多
Severe tool wear and poor surface quality are the main problems during micro machining of cemented carbide.In this work,an innovative hybrid process of laser-induced oxidation assisted micro milling(LOMM)was proposed ...Severe tool wear and poor surface quality are the main problems during micro machining of cemented carbide.In this work,an innovative hybrid process of laser-induced oxidation assisted micro milling(LOMM)was proposed to solve the problems.A nanosecond laser was utilized to induce oxidation of the WC-20%Co material,producing loose oxide which was easy to remove.The micro machinability of the material was improved by laser-induced oxidation.The oxidation mechanisms of cemented carbide were studied.A microgroove with a depth of 2.5 mm and aspect ratio of 5 was fabricated successfully.The milling force,surface quality and tool wear mechanisms were investigated.For comparison,a microgroove was also fabricated with conventional micro milling(COMM)using identical milling parameters.Results revealed that in LOMM the milling force and tool wear rate were extremely low during removing the oxide.The machined surface quality and dimensional accuracy achieved by LOMM were superior to those obtained by COMM.The surface roughness Saof the microgroove bottom reached 88 nm in LOMM,while the cross-sectional geometry of the microgroove was a trapezoid.Perpendicularity of the microgroove sidewall machined by LOMM was better than that by COMM.The tool wear forms in LOMM were coating spalling and slight tool nose breakage.Compared with COMM,the tool life in LOMM was prolonged significantly.It indicates that the proposed hybrid process is an effective and efficient way to fabricate high aspect ratio micro-features with high dimensional accuracy.展开更多
Micro machining has growing number of applications in various industries such as biomedical, automotive, aerospace, micro-sensor, micro-actuator and jewelry industries. Small-sized freeform titanium parts are frequent...Micro machining has growing number of applications in various industries such as biomedical, automotive, aerospace, micro-sensor, micro-actuator and jewelry industries. Small-sized freeform titanium parts are frequently needed in the biomedical applications, especially in the implantations such as mini-blood pumps and mini left-ventricular assist devices, finger joint replacements and small bone implants. Most of the small-sized titanium parts with freeform geometries are machined using micro ball-end milling before polishing and other surface treatments. Decreasing the cycle time of the machining parts is important for the productivity. In order to reduce the cycle time of the roughing process in the micro ball-end milling, this paper investigates the imple- mentation of a previously developed force-based feedrate scheduling （FFS） technique on micro milling of freeform titanium parts. After briefly introducing the instantaneous micro milling forces in micro ball-end milling of titanium parts with freeform surfaces, the FFS technique is implemented in the rough machining of a freeform titanium surface to demonstrate the cycle time reduction potentials via virtual micro milling simulations.展开更多
Over a century,metal cutting has been observed as a vital process in the domain of manufacturing.Among the numerous available metal-cutting processes,milling has been considered as one of the most employable processes...Over a century,metal cutting has been observed as a vital process in the domain of manufacturing.Among the numerous available metal-cutting processes,milling has been considered as one of the most employable processes to machine a variety of engineering materials productively.In the milling process,material removal occurs when the workpiece is fed against a rotating tool with multiple cutting edges.In order to maximize the profitability of metal cutting operations,it is essential that the various input and output variable relationships are analyzed and optimized.The experimental method of studying milling processes is costly and time demanding,particularly when a large variety of elements such as cutting tool shape,materials,cutting conditions,and so on,are included.Due to these issues,other alternatives emerged in the form of mathematical simulations that employ numerical methods.The finite element approaches have well-proven to be the most practical and commonly utilized numerical methods.The finite element model(FEM)can be used to determine the various physical interactions occurring during the machining process along with the prediction of various milling characteristics,such as cutting forces,cutting temperature,stresses,etc.,with the help of milling inputs.In the present article,various research studies in the broad milling process domain practiced with numerous finite element approaches have been critically reviewed and reported.It further highlights the several experimental and finite element approaches-based research studies that attempted to analyze and optimize the overall performance of the different milling processes.In recent years,various investigators have explored numerous ways to enhance milling performance by probing the different factors that influence the quality attributes.Some of the studies have also been found to be focused on the economic impacts of milling and various process inputs that affect milling performance.Furthermore,various milling factors’impact on the performance characteristics are presented and critically discussed.The issues related to the recent improvements in tool-work interaction modeling,experimental techniques for acquiring various milling performance measures,and the aspects of turn and micro-milling with finite element-based modeling have been further highlighted.Among the various available classifications in the milling process as employed in industries,face milling is more strongly established compared to other versions such as end milling,helical milling,gear milling,etc.The final section of this research article explores the various research aspects and outlines future research directions.展开更多
文摘The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and low working gap was investigated by the Grey-Taguchi method.The influences of peak current,pulse on-time,pulse off-time and spark gap on electrode wear（EW）,material removal rate（MRR） and working gap（WG） in the micro milling electrical discharge machining of Inconel 718 were analyzed.The experimental results show that the electrode wear decreases from 5.6×10-9 to 5.2×10-9 mm3/min,the material removal rate increases from 0.47×10-8 to 1.68×10-8 mm3/min,and the working gap decreases from 1.27 to 1.19 μm under optimal micro milling electrical discharge machining process parameters.Hence,it is clearly shown that multiple performance characteristics can be improved by using the Grey-Taguchi method.
基金Supported by National Natural Science Foundation of China(Grant No.50935003)National Numerical Control Major Projects of China(Grant No.2013ZX04001000215)
文摘Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes （ACEs） are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye （ACE） with surface roughness （Ra） below 0.12 p.m is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.
基金Supported by National Natural Science Foundation of China (No. 50935003)
文摘Based on microscope and image processing, a new method of auto tool setting for micro milling was presented. Firstly, a realtime image of tool setting area was obtained by microscope and CCD camera, then image processing was carried out on this image and the gap between the tool and workpiece was calculated. The gap measurement was sent to motion controlling card to make the tool approach to the surface of workpiece. These steps were repeated until the gap is zero, which means that tool setting was finished. Moreover, a reliability verification test was conducted. Results indicated that the precision of tool setting is satisfactory.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50935003)
文摘Micro milling has many advantages in fabricating three-dimensional(3D) structure in micrometer scale. The micro milling machine tool with high positioning accuracy is of great importance for getting micro structure with high profile precision and good surface quality. Meanwhile, the method of position error compensation is a good way to improve the accuracy of the micro milling machine tools. In this paper,a software method is adopted to compensate the positioning error and improve the positioning accuracy. According to error cancellation theory,the compensation values are generated and compensation tables are built to adjust the positioning error in the NC system based on Industrial Motion and Automation Control( IMAC). The positioning accuracy of linear motor is ± 0. 3 μm without backlash after compensation. In order to verify the effectiveness of compensation on the machining performance,concave spherical surfaces are processed on the micro milling machine tool. The experimental results show that the profile radius error of the spherical surface machined with compensation decreases more than 60%.
基金the National Natural Science Foundation of China(No.51705249)the China Postdoctoral Science Foundation(No.2019M661823)+1 种基金the Aeronautical Science Foundation of China(No.2017ZE52047)the 111 Project on Key Technology in Sustainable Manufacturing(No.B16024)。
文摘Severe tool wear and poor surface quality are the main problems during micro machining of cemented carbide.In this work,an innovative hybrid process of laser-induced oxidation assisted micro milling(LOMM)was proposed to solve the problems.A nanosecond laser was utilized to induce oxidation of the WC-20%Co material,producing loose oxide which was easy to remove.The micro machinability of the material was improved by laser-induced oxidation.The oxidation mechanisms of cemented carbide were studied.A microgroove with a depth of 2.5 mm and aspect ratio of 5 was fabricated successfully.The milling force,surface quality and tool wear mechanisms were investigated.For comparison,a microgroove was also fabricated with conventional micro milling(COMM)using identical milling parameters.Results revealed that in LOMM the milling force and tool wear rate were extremely low during removing the oxide.The machined surface quality and dimensional accuracy achieved by LOMM were superior to those obtained by COMM.The surface roughness Saof the microgroove bottom reached 88 nm in LOMM,while the cross-sectional geometry of the microgroove was a trapezoid.Perpendicularity of the microgroove sidewall machined by LOMM was better than that by COMM.The tool wear forms in LOMM were coating spalling and slight tool nose breakage.Compared with COMM,the tool life in LOMM was prolonged significantly.It indicates that the proposed hybrid process is an effective and efficient way to fabricate high aspect ratio micro-features with high dimensional accuracy.
文摘Micro machining has growing number of applications in various industries such as biomedical, automotive, aerospace, micro-sensor, micro-actuator and jewelry industries. Small-sized freeform titanium parts are frequently needed in the biomedical applications, especially in the implantations such as mini-blood pumps and mini left-ventricular assist devices, finger joint replacements and small bone implants. Most of the small-sized titanium parts with freeform geometries are machined using micro ball-end milling before polishing and other surface treatments. Decreasing the cycle time of the machining parts is important for the productivity. In order to reduce the cycle time of the roughing process in the micro ball-end milling, this paper investigates the imple- mentation of a previously developed force-based feedrate scheduling （FFS） technique on micro milling of freeform titanium parts. After briefly introducing the instantaneous micro milling forces in micro ball-end milling of titanium parts with freeform surfaces, the FFS technique is implemented in the rough machining of a freeform titanium surface to demonstrate the cycle time reduction potentials via virtual micro milling simulations.
文摘Over a century,metal cutting has been observed as a vital process in the domain of manufacturing.Among the numerous available metal-cutting processes,milling has been considered as one of the most employable processes to machine a variety of engineering materials productively.In the milling process,material removal occurs when the workpiece is fed against a rotating tool with multiple cutting edges.In order to maximize the profitability of metal cutting operations,it is essential that the various input and output variable relationships are analyzed and optimized.The experimental method of studying milling processes is costly and time demanding,particularly when a large variety of elements such as cutting tool shape,materials,cutting conditions,and so on,are included.Due to these issues,other alternatives emerged in the form of mathematical simulations that employ numerical methods.The finite element approaches have well-proven to be the most practical and commonly utilized numerical methods.The finite element model(FEM)can be used to determine the various physical interactions occurring during the machining process along with the prediction of various milling characteristics,such as cutting forces,cutting temperature,stresses,etc.,with the help of milling inputs.In the present article,various research studies in the broad milling process domain practiced with numerous finite element approaches have been critically reviewed and reported.It further highlights the several experimental and finite element approaches-based research studies that attempted to analyze and optimize the overall performance of the different milling processes.In recent years,various investigators have explored numerous ways to enhance milling performance by probing the different factors that influence the quality attributes.Some of the studies have also been found to be focused on the economic impacts of milling and various process inputs that affect milling performance.Furthermore,various milling factors’impact on the performance characteristics are presented and critically discussed.The issues related to the recent improvements in tool-work interaction modeling,experimental techniques for acquiring various milling performance measures,and the aspects of turn and micro-milling with finite element-based modeling have been further highlighted.Among the various available classifications in the milling process as employed in industries,face milling is more strongly established compared to other versions such as end milling,helical milling,gear milling,etc.The final section of this research article explores the various research aspects and outlines future research directions.
