scholarly journals Fabrication of Micro-Parts with High-Aspect Ratio Micro-Hole Array by Micro-Powder Injection Molding

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1864 ◽  
Author(s):  
Changrui Wang ◽  
Zhen Lu ◽  
Kaifeng Zhang
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Linear Shrinkage ◽  
Powder Injection ◽  
Hole Array ◽  
Particle Sizes ◽  
Crystalline Particle ◽  
Average Deviation ◽  
Micro Holes ◽  
Micro Hole

The present study investigated high-aspect ratio micro-hole array parts which were made by ZrO2 micro-powder with different particle sizes and micro-powder injection molding technology. It analysed the influence of particle sizes on feedstock, debinding and sintering of ceramic nozzles with multi-micro-holes. The forming quality of ceramic nozzles with multi-micro-holes was discussed in this paper. The results show that the two mixed ZrO2 feedstocks have fine uniformity. The average deviation of the feedstock made with 200 nm powder was −2%, and the average deviation of the feedstock made with 100 nm powder was −7.1%. The sample showed certain sintering characteristics which provided better strength (11.10 MPa) to parts after debinding. The linear shrinkage and the density of the two powder samples at different sintering temperatures increased as the sintering temperature increased. If the temperature continued to increase, the linear shrinkage and the density decreased. The highest hardness and flexural strength values of the ZrO2 sample with 200 nm powder used were: 1265.5 HV and 453.4 MPa, and the crystalline particle size was 0.36 μm. The highest hardness and flexural strength values of the ZrO2 sample with 100 nm powder used were: 1425.8 HV and 503.6 MPa, and the crystalline particle size was 0.18 μm. The ceramic nozzles with multi-micro holes shrunk to nearly the same axial, radial and circumferential directions during sintering. After sintering, the roundness of ceramic micro-hole met the user requirements, and the circular hole had a high parallelism in the axial direction. The micropore diameter was 450 ± 5 μm, and it was possible to control the dimensional accuracy within 1.5% after sintering. The study presented a superior application prospect for high-aspect ratio micro hole array parts in aerospace, electronics and biomedicine.

Influence of the Planetary Movement of Tool on the Aspect Ratio of Micro Holes Machined by Micro-Ultrasonic Machining

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Senwang Lei ◽  
Zuyuan Yu ◽  
Kai Zhou ◽  
Jianzhong Li ◽  
Renke Kang
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Ultrasonic Machining ◽  
Processing Efficiency ◽  
Machining Speed ◽  
Micro Holes ◽  
Hard And Brittle Materials ◽  
Micro Hole ◽  
Micro Tool ◽  
Movement Parameters

The micro-ultrasonic machining (USM) is suitable for machining hard and brittle materials. When a micro hole is drilled deeply using micro-USM, machining speed slows down and the breakage of micro tool may occur. To solve this problem, this paper proposes the application the planetary movement of micro tool in high-aspect ratio micro holes drilling by micro-USM. The micro holes of about 92 μm in diameter with an aspect ratio larger than ten have been machined. The processing efficiency has been improved. The influence of planetary movement parameters on processing efficiency has been investigated

scholarly journals Precision EDM of Micron-Scale Diameter Hole Array Using in-Process Wire Electro-Discharge Grinding High-Aspect-Ratio Microelectrodes

Micromachines ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 17
Author(s):  
Zhixiang Zou ◽  
Zhongning Guo ◽  
Qinming Huang ◽  
Taiman Yue ◽  
Jiangwen Liu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Turbine Blades ◽  
Hole Array ◽  
Machining Accuracy ◽  
Micro Edm ◽  
Wire Vibration ◽  
Micro Hole ◽  
The Wire

Micro-electrical discharge machining (micro-EDM) is a good candidate for processing micro-hole arrays, which are critical features of micro-electro-mechanical systems (MEMS), diesel injector nozzles, inkjet printheads and turbine blades, etc. In this study, the wire vibration of the wire electro-discharge grinding (WEDG) system has been analyzed theoretically, and, accordingly, an improved WEDG method was developed to fabricate micron-scale diameter and high-aspect-ratio microelectrodes for the in-process micro-EDM of hole array with hole diameter smaller than 20 μm. The improved method has a new feature of a positioning device to address the wire vibration problem, and thus to enhance microelectrodes fabrication precision. Using this method, 14 μm diameter microelectrodes with less than 0.4 μm deviation and an aspect ratio of 142, which is the largest aspect ratio ever reported in the literature, were successfully fabricated. These microelectrodes were then used to in-process micro-EDM of hole array in stainless steel. The effects of applied voltage, current and pulse frequency on hole dimensional accuracy and microelectrode wear were investigated. The optimal processing parameters were selected using response–surface experiments. To improve machining accuracy, an in-process touch-measurement compensation strategy was applied to reduce the cumulative compensation error of the micro-EDM process. Using such a system, micro-hole array (2 × 80) with average entrance diameter 18.91 μm and average exit diameter 17.65 μm were produced in 50 μm thickness stainless steel sheets, and standard deviations of hole entrance and exit sides of 0.44 and 0.38 μm, respectively, were achieved.

Numerical Simulation of High-Aspect-Ratio Micro-Hole Electroforming with External Magnetic Field

2010 ◽  
Vol 42 ◽  
pp. 13-16
Author(s):  
Wei Li ◽  
Ping Mei Ming ◽  
Wu Ji Jiang ◽  
Yin Ding Lv
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Flow State ◽  
Cathode Electrode ◽  
Micro Hole ◽  
Fluent Software ◽  
The Magnetic Field ◽  
Enhance Mass

In this paper, the influences of applied magnetic field on flow state during electroforming of the high-aspect-ratio (HAR) blind micro-hole were numerically analyzed using the Fluent software. The results showed that, when microelectroforming of nickel without external agitation, three vortexes could form due to the magnetohydrodynamic (MHD) effect within the HAR micro-hole with magnetic field in parallel to cathode-electrode surface, and the flow rate in the micro-hole increased with the increase of the magnetic field and current density. The MHD effect helped to enhance mass transfer during the microelectroforming of HAR microstructures.

EDM of high aspect ratio micro-holes on Ti-6Al-4V alloy by synchronizing energy interactions

2020 ◽  
Vol 35 (11) ◽  
pp. 1188-1203 ◽  
Author(s):  
Ramver Singh ◽  
Akshay Dvivedi ◽  
Pradeep Kumar
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Micro Holes

Fabrication of High-Aspect Ratio Micro Holes on Hard Brittle Materials -Study on Electrorheological Fluid-Assisted Micro Ultrasonic Machining-

2008 ◽  
Vol 389-390 ◽  
pp. 264-270 ◽  
Author(s):  
T. Tateishi ◽  
Nobuhito Yoshihara ◽  
Ji Wang Yan ◽  
Tsunemoto Kuriyagawa
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Brittle Materials ◽  
Electrorheological Fluid ◽  
Machining Accuracy ◽  
Machining Efficiency ◽  
Ultrasonic Machining ◽  
Auxiliary Electrode ◽  
Abrasive Grains ◽  
Micro Holes

Ultrasonic machining (USM) is an effective method for machining of hard brittle materials. In this process, the slurry is supplied to the gap between the workpiece and the ultrasonic vibrating tool, and the materials are removed by the impacts of the abrasive grains that are pressurized by an ultrasonic vibrating tool. The purpose of this research is to achieve precise and efficient microfabrication on hard brittle materials by USM. However, in the case of microfabrication, chipping which is generally observed around the edges of machined micro holes and grooves, deteriorates the machining accuracy. In addition, there is another problem in that the machining efficiency decreases with the progress of the machining. Electrorheological fluid-assisted USM has been proposed as a countermeasure to these problems. In the present study, the problems and countermeasures associated with the machining of high-aspect ratio micro holes in hard brittle materials by electrorheological fluid-assisted USM are investigated. By positioning an auxiliary electrode under the workpiece, it becomes possible to keep the electric field high even when the machining depth becomes large. As a result, high-precision and high-aspect ratio micro holes can be machined on hard brittle materials.

Measurement of micro-hole with high aspect ratio by double optical fibers coupling

2008 ◽  
Author(s):  
Jiwen Cui ◽  
Jiubin Tan ◽  
Fei Wang ◽  
Chuanxi Song
Keyword(s):  
Aspect Ratio ◽  
Optical Fibers ◽  
High Aspect Ratio ◽  
Micro Hole

Modeling Aspect Ratio of a Micro EDM Hole

2010 ◽  
Vol 126-128 ◽  
pp. 829-834
Author(s):  
G. Yin ◽  
Z. Yu ◽  
C. An ◽  
J. Li
Keyword(s):  
Aspect Ratio ◽  
Electrical Discharge Machining ◽  
Micro Edm ◽  
Metallic Materials ◽  
Micro Electrical Discharge Machining ◽  
Proposed Model ◽  
Micro Holes ◽  
Micro Hole ◽  
The Difference ◽  
Discharge Gap

Micro electrical discharge machining (EDM) has the ability to drill micro holes with high accuracy in metallic materials. The aspect ratio of a micro hole generated by micro EDM is usually higher than those by other processes such as etching, mechanical drilling, and laser. However, it was found that the drilling speed of micro EDM slows down and even stops when the aspect ratio reaches a certain value. To understand this phenomenon, a theoretical model is proposed based on the fluid mechanics and surface tension. Experiments under different machining conditions are carried to verify this model. Experimental results agree with the theoretical values, which indicate the validity of the proposed model. The difference between the theoretical values and the real values might be caused by the debris and the temperature in the discharge gap, which are ignored in the model.

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