Pub Date : 2022-11-14DOI: 10.1177/25165984221129449
Rajesh Sahoo, Deepak Kumar, N. K. Singh, Vivek Bajpai
In the current scenario, micro-manufacturing through the electro-discharge machining (EDM) process is a prominent technique for achieving desired complex micro/nano-features of any product. The precision and accuracy of producing features are the prerequisites of micro-machining. The current work aims to check the feasibility of the novel Maglev EDM for fabricating micro-holes on a thin nickel sheet (thickness = 500 μm). The study presents the viability of the newly developed system by comparing it with the conventional EDM process. A pure direct current power supply is assembled with a magnetic levitation-based gap monitoring mechanism to overcome the setbacks of conventional EDM. The novel setup utilizes the combined effect of the permanent electromagnet to diminish arcing and short-circuiting. The control parameters for the operation were 12 V open-circuit voltage and 2 A peak current while maintaining a duty factor of 95.564 percent. The measured discharge voltage and discharge current were 6.64 V and 900 mA, respectively. Tungsten rod (ø 650 μm) and deionized water were used as a tool and a dielectric medium, respectively, for the experiment. Further, the machined micro-hole and micro-tool analysis have been carried out using high-resolution microscopy, scanning electron microscopy and energy dispersive spectroscopy reports. The newly developed Maglev EDM’s feasibility to produce micro-holes on conductive materials has been confirmed in the present work with an average material removal rate of 40 μg/min.
{"title":"Fabrication of micro-hole using novel Maglev EDM","authors":"Rajesh Sahoo, Deepak Kumar, N. K. Singh, Vivek Bajpai","doi":"10.1177/25165984221129449","DOIUrl":"https://doi.org/10.1177/25165984221129449","url":null,"abstract":"In the current scenario, micro-manufacturing through the electro-discharge machining (EDM) process is a prominent technique for achieving desired complex micro/nano-features of any product. The precision and accuracy of producing features are the prerequisites of micro-machining. The current work aims to check the feasibility of the novel Maglev EDM for fabricating micro-holes on a thin nickel sheet (thickness = 500 μm). The study presents the viability of the newly developed system by comparing it with the conventional EDM process. A pure direct current power supply is assembled with a magnetic levitation-based gap monitoring mechanism to overcome the setbacks of conventional EDM. The novel setup utilizes the combined effect of the permanent electromagnet to diminish arcing and short-circuiting. The control parameters for the operation were 12 V open-circuit voltage and 2 A peak current while maintaining a duty factor of 95.564 percent. The measured discharge voltage and discharge current were 6.64 V and 900 mA, respectively. Tungsten rod (ø 650 μm) and deionized water were used as a tool and a dielectric medium, respectively, for the experiment. Further, the machined micro-hole and micro-tool analysis have been carried out using high-resolution microscopy, scanning electron microscopy and energy dispersive spectroscopy reports. The newly developed Maglev EDM’s feasibility to produce micro-holes on conductive materials has been confirmed in the present work with an average material removal rate of 40 μg/min.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126042692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-14DOI: 10.1177/25165984221128519
Vineet Kumar, G. Samuel
Nickel-based alloys (Nimonic 90) are one of the most used materials for aircraft parts, gas turbine components and fasteners due to their inherent properties such as high strength at elevated temperature, good corrosion resistance, high stability, high wear resistance and low thermal conductivity. Because of the above-mentioned properties, Nimonic 90 alloy is difficult to machine, and the roughness obtained by machining of nimonic alloy is comparatively rough. The existing theoretically developed mathematical equations for roughness measurement do not consist of all the machining parameters. It lacks some of the effective roughness parameters such as depth of cut, spindle speed and cutting-edge angle. This article proposes a novel mathematical/geometrical model for the prediction of surface roughness using fundamental geometrical properties of tool and workpiece. For developing the mathematical model, the nose radius of the cutting tool insert is assumed as a straight line (arc length). The principal cutting-edge angle is introduced in the geometrically developed novel model. The developed mathematical/geometrical model comprises mainly depth of cut, principal cutting-edge angle, nose radius, spindle speed and feed. In micro turning, surface roughness increases with an increase in feed and depth of cut. A rough surface, compared to conventional turning, is produced while micro turning due to edge ploughing and rubbing when the chip thickness is lesser than the edge radius. This model is validated by conducting micro-turning experiments on nickel-based superalloy (Nimonic 90) using aluminium titanium nitride physical vapour deposition coated tungsten carbide micro inserts. The surface roughness is significantly affected when the cutting-edge comes in contact with the workpiece; it is because of the imperfect geometry of the nose of the cutting tool. A slight variation of surface roughness with the depth of cut has also been observed. A good correlation is observed between the predicted and experimentally measured roughness values.
{"title":"Modelling and validation of surface roughness in micro-turned nickel-based alloys (Nimonic 90)","authors":"Vineet Kumar, G. Samuel","doi":"10.1177/25165984221128519","DOIUrl":"https://doi.org/10.1177/25165984221128519","url":null,"abstract":"Nickel-based alloys (Nimonic 90) are one of the most used materials for aircraft parts, gas turbine components and fasteners due to their inherent properties such as high strength at elevated temperature, good corrosion resistance, high stability, high wear resistance and low thermal conductivity. Because of the above-mentioned properties, Nimonic 90 alloy is difficult to machine, and the roughness obtained by machining of nimonic alloy is comparatively rough. The existing theoretically developed mathematical equations for roughness measurement do not consist of all the machining parameters. It lacks some of the effective roughness parameters such as depth of cut, spindle speed and cutting-edge angle. This article proposes a novel mathematical/geometrical model for the prediction of surface roughness using fundamental geometrical properties of tool and workpiece. For developing the mathematical model, the nose radius of the cutting tool insert is assumed as a straight line (arc length). The principal cutting-edge angle is introduced in the geometrically developed novel model. The developed mathematical/geometrical model comprises mainly depth of cut, principal cutting-edge angle, nose radius, spindle speed and feed. In micro turning, surface roughness increases with an increase in feed and depth of cut. A rough surface, compared to conventional turning, is produced while micro turning due to edge ploughing and rubbing when the chip thickness is lesser than the edge radius. This model is validated by conducting micro-turning experiments on nickel-based superalloy (Nimonic 90) using aluminium titanium nitride physical vapour deposition coated tungsten carbide micro inserts. The surface roughness is significantly affected when the cutting-edge comes in contact with the workpiece; it is because of the imperfect geometry of the nose of the cutting tool. A slight variation of surface roughness with the depth of cut has also been observed. A good correlation is observed between the predicted and experimentally measured roughness values.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"2557 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128759295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-14DOI: 10.1177/25165984221131400
R. Helgason, Jino Fathy, Yongjun Lai
Laser cutting is often used in the fabrication of Polydimethylsiloxane (PDMS) substrates for novel microdevices such as wearable sensors and microfluidic devices. PDMS is a thermosetting polymer whose material properties are affected by the thermal conditions during the curing process. Since laser cutting exposes the cutting material to high temperatures, this might affect the heat-sensitive material properties. In this work, we examine how laser cutting affects the stiffness of PDMS by measuring the Young’s modulus of PDMS and comparing that to the Young’s modulus of laser-cut PDMS. We find an increase in the Young’s modulus from 0.34 to 0.37 MPa (9%) for PDMS mixed at a ratio of 20:1 base to curing agent. For 10:1 ratio PDMS, we find the increase in Young’s modulus is 31%, from 1.02 to 1.34 MPa.
{"title":"The effect of laser cutting on the Young’s modulus of Polydimethylsiloxane","authors":"R. Helgason, Jino Fathy, Yongjun Lai","doi":"10.1177/25165984221131400","DOIUrl":"https://doi.org/10.1177/25165984221131400","url":null,"abstract":"Laser cutting is often used in the fabrication of Polydimethylsiloxane (PDMS) substrates for novel microdevices such as wearable sensors and microfluidic devices. PDMS is a thermosetting polymer whose material properties are affected by the thermal conditions during the curing process. Since laser cutting exposes the cutting material to high temperatures, this might affect the heat-sensitive material properties. In this work, we examine how laser cutting affects the stiffness of PDMS by measuring the Young’s modulus of PDMS and comparing that to the Young’s modulus of laser-cut PDMS. We find an increase in the Young’s modulus from 0.34 to 0.37 MPa (9%) for PDMS mixed at a ratio of 20:1 base to curing agent. For 10:1 ratio PDMS, we find the increase in Young’s modulus is 31%, from 1.02 to 1.34 MPa.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132353442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-14DOI: 10.1177/25165984221123196
Aruna Kotlapati, S. Hiremath
Aluminum silicon carbide metal matrix composite (Al-SiC MMC) is widely used because of its exceptional mechanical and thermal properties. Some engineering applications include aerospace, automobile, electronics, and medical devices. In the present investigation, aluminum 7075 alloy (Al-7075) as a matrix material with reinforcement particles of 10% silicon carbide (SiC) is fabricated using stir casting. The developed Al-SiC MMC is machined using an in-house developed micro-electro discharge machine (µ-EDM) setup. Experiments are carried out with input parameters—voltage (V), capacitance (µF), and pulse-on time (µs)—to analyze the responses such as hole depth (HD), material removal rate (MRR), tool wear rate (TWR), surface roughness (SR), and circularity error (CE). Taguchi L16 orthogonal array is adopted to conduct 16 experiments with varying process parameters for 5 minutes’ duration with a copper tool electrode of Ø720 µm on the Al-SiC MMC workpiece of size 20 mm × 20 mm × 2.5 mm. The dielectric medium used for all experimentation is EDM oil. The resultant blind holes are characterized using scanning electron microscopy (SEM) images and a 3D profilometer. Later, the signal-to-noise ( S/N) ratio technique is used to optimize the process parameters to enhance individual output responses. The obtained results are discussed in the article. Further, analysis of variance (ANOVA) is performed to find out the contribution of each parameter to the output responses. Grey relational analysis (GRA) is also used for multiobjective optimization to get quality blind holes. The best parametric combination obtained through GRA are at 28 V, 100 µF, and 100 µs, resulting in 823 µm of HD, 0.38 mg/min of MRR, 0.10 mg/min of TWR, 8.98 µm of SR, and 48.37 µm of CE.
铝碳化硅金属基复合材料(Al-SiC MMC)因其优异的力学和热性能而得到广泛应用。一些工程应用包括航空航天、汽车、电子和医疗设备。以Al-7075为基体材料，以10%碳化硅(SiC)为增强颗粒，采用搅拌铸造法制备了Al-7075合金。开发的Al-SiC MMC使用内部开发的微电子放电机(µ-EDM)装置进行加工。实验采用输入参数——电压(V)、电容(µF)和脉冲导通时间(µs)——来分析孔深(HD)、材料去除率(MRR)、刀具磨损率(TWR)、表面粗糙度(SR)和圆度误差(CE)等响应。采用田口L16正交阵列，在尺寸为20 mm × 20 mm × 2.5 mm的Al-SiC MMC工件上，以Ø720µm铜工具电极进行了16次不同工艺参数的实验，实验时间为5 min。所有实验使用的介质为电火花加工油。利用扫描电子显微镜(SEM)图像和三维轮廓仪对所产生的盲孔进行了表征。随后，采用信噪比(S/N)技术对工艺参数进行优化，以增强单个输出响应。本文对所得结果进行了讨论。进一步，进行方差分析(ANOVA)以找出每个参数对输出响应的贡献。采用灰色关联分析(GRA)进行多目标优化，得到高质量的盲孔。通过GRA获得的最佳参数组合为28 V、100µF、100µs, HD为823µm, MRR为0.38 mg/min, TWR为0.10 mg/min, SR为8.98µm, CE为48.37µm。
{"title":"Machinability and parametric optimization of aluminum silicon carbide metal matrix composite (Al-SiC MMC) machined through µ-EDM","authors":"Aruna Kotlapati, S. Hiremath","doi":"10.1177/25165984221123196","DOIUrl":"https://doi.org/10.1177/25165984221123196","url":null,"abstract":"Aluminum silicon carbide metal matrix composite (Al-SiC MMC) is widely used because of its exceptional mechanical and thermal properties. Some engineering applications include aerospace, automobile, electronics, and medical devices. In the present investigation, aluminum 7075 alloy (Al-7075) as a matrix material with reinforcement particles of 10% silicon carbide (SiC) is fabricated using stir casting. The developed Al-SiC MMC is machined using an in-house developed micro-electro discharge machine (µ-EDM) setup. Experiments are carried out with input parameters—voltage (V), capacitance (µF), and pulse-on time (µs)—to analyze the responses such as hole depth (HD), material removal rate (MRR), tool wear rate (TWR), surface roughness (SR), and circularity error (CE). Taguchi L16 orthogonal array is adopted to conduct 16 experiments with varying process parameters for 5 minutes’ duration with a copper tool electrode of Ø720 µm on the Al-SiC MMC workpiece of size 20 mm × 20 mm × 2.5 mm. The dielectric medium used for all experimentation is EDM oil. The resultant blind holes are characterized using scanning electron microscopy (SEM) images and a 3D profilometer. Later, the signal-to-noise ( S/N) ratio technique is used to optimize the process parameters to enhance individual output responses. The obtained results are discussed in the article. Further, analysis of variance (ANOVA) is performed to find out the contribution of each parameter to the output responses. Grey relational analysis (GRA) is also used for multiobjective optimization to get quality blind holes. The best parametric combination obtained through GRA are at 28 V, 100 µF, and 100 µs, resulting in 823 µm of HD, 0.38 mg/min of MRR, 0.10 mg/min of TWR, 8.98 µm of SR, and 48.37 µm of CE.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133401755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-01DOI: 10.1177/25165984221086421
Mohan K. Pradhan, Ashok Kumar
{"title":"V. K. Jain (Ed.) (2014). Introduction to Micromachining (second edition). New Delhi, India: Narosa Publishing House. 624 pp. $43.12 (Paperback), ISBN: 978-81-8487-361-0.","authors":"Mohan K. Pradhan, Ashok Kumar","doi":"10.1177/25165984221086421","DOIUrl":"https://doi.org/10.1177/25165984221086421","url":null,"abstract":"","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126022569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-17DOI: 10.1177/25165984221123205
Sandesh Birla, S. Alya, R. Singh
Restoration of high-value components via additive manufacturing requires autonomous surface scanning and defect identification. The 3D free-form surface can be reconstructed with a point cloud obtained from the scanning. Laser line triangulation-based surface scanning is a promising method for generating a 3D point cloud of the component surface. In this article, a robotic defect scanning system developed using py_openshowvar, an open-source cross-platform communication interface is presented. For effective scanning of micro-scale features with minimal noise, it is crucial to optimize the scanning parameters. The scanner parameters such as exposure time and stand-off distance have been optimized for accurate feature detection. After selecting optimal scanning parameters, a generic algorithm is presented for generating a scanning path for automatic scanning of the 3D parts. Surfaces with pre-fabricated micro-defects are automatically scanned using this algorithm, and an integrated image-processing-based defect identification technique is presented. The geometries obtained from the presented technique were validated using focus variation microscopy, and the results are in good agreement with actual defect geometry, and the measurement error is below 9%.
{"title":"An integrated image processing approach for 3D scanning and micro-defect detection","authors":"Sandesh Birla, S. Alya, R. Singh","doi":"10.1177/25165984221123205","DOIUrl":"https://doi.org/10.1177/25165984221123205","url":null,"abstract":"Restoration of high-value components via additive manufacturing requires autonomous surface scanning and defect identification. The 3D free-form surface can be reconstructed with a point cloud obtained from the scanning. Laser line triangulation-based surface scanning is a promising method for generating a 3D point cloud of the component surface. In this article, a robotic defect scanning system developed using py_openshowvar, an open-source cross-platform communication interface is presented. For effective scanning of micro-scale features with minimal noise, it is crucial to optimize the scanning parameters. The scanner parameters such as exposure time and stand-off distance have been optimized for accurate feature detection. After selecting optimal scanning parameters, a generic algorithm is presented for generating a scanning path for automatic scanning of the 3D parts. Surfaces with pre-fabricated micro-defects are automatically scanned using this algorithm, and an integrated image-processing-based defect identification technique is presented. The geometries obtained from the presented technique were validated using focus variation microscopy, and the results are in good agreement with actual defect geometry, and the measurement error is below 9%.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"8 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129363974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-21DOI: 10.1177/25165984221086439
Sumit, R. Shukla, A. Sinha
Proportional integral derivative (PID) controllers are widely used to solve different control engineering problems. To know the dynamic behaviour of a working plant by mathematical modelling is quite challenging. Finite element method (FEM) is a well-known technique and broadly used for the modelling of engineering systems. This article presents the FEM-based heuristic approach to design and optimize the PID controllers. The ‘allowed area method’ has been used for the formulation of the objective function followed by the tuning of the PID controller. First, the proposed approach is tested on 2-degree of freedom (DOF) mass-spring-damper (MSD) system. FEM modelling of 2-DOF MSD system with PID controller has been carried out in COMSOL Multiphysics and coupling of particle swarm optimization (PSO) has been carried out with the FEM model of the MSD system, for the optimization of PID controller gain. The FEM results are in good agreement with the analytical one. Next, the established method is applied to design and optimize the PID controller gain to control the vibration of a cantilever beam using piezoelectric actuator. Similar to the MSD system, FEM modelling of PID controller for the smart beam has been carried out in COMSOL Multiphysics, and the coupling of PSO is carried out with the FEM model of the smart beam for the optimization of PID controller gain. Simulation of the uncontrolled and controlled responses of the smart beam is carried out at the optimum controller gain for free vibration and step excitation. The piezoelectric actuator of smart beam has successfully damped the vibration within approximately 2.5 s.
{"title":"Study of PID controller gain for active vibration control using FEM based particle swarm optimization in COMSOL multiphysics","authors":"Sumit, R. Shukla, A. Sinha","doi":"10.1177/25165984221086439","DOIUrl":"https://doi.org/10.1177/25165984221086439","url":null,"abstract":"Proportional integral derivative (PID) controllers are widely used to solve different control engineering problems. To know the dynamic behaviour of a working plant by mathematical modelling is quite challenging. Finite element method (FEM) is a well-known technique and broadly used for the modelling of engineering systems. This article presents the FEM-based heuristic approach to design and optimize the PID controllers. The ‘allowed area method’ has been used for the formulation of the objective function followed by the tuning of the PID controller. First, the proposed approach is tested on 2-degree of freedom (DOF) mass-spring-damper (MSD) system. FEM modelling of 2-DOF MSD system with PID controller has been carried out in COMSOL Multiphysics and coupling of particle swarm optimization (PSO) has been carried out with the FEM model of the MSD system, for the optimization of PID controller gain. The FEM results are in good agreement with the analytical one. Next, the established method is applied to design and optimize the PID controller gain to control the vibration of a cantilever beam using piezoelectric actuator. Similar to the MSD system, FEM modelling of PID controller for the smart beam has been carried out in COMSOL Multiphysics, and the coupling of PSO is carried out with the FEM model of the smart beam for the optimization of PID controller gain. Simulation of the uncontrolled and controlled responses of the smart beam is carried out at the optimum controller gain for free vibration and step excitation. The piezoelectric actuator of smart beam has successfully damped the vibration within approximately 2.5 s.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115396603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In electro-discharge machining (EDM), the material removal takes place by precisely controlled sparks that occur between tool and workpiece separated with a spark gap in the presence of a dielectric. Generally, the non-contacting type and less material removal rates are attributed to attain a good surface finish and close dimensional tolerances during an EDM of monolithic metals and alloys. But the dimensional accuracy and surface integrity parameters would considerably affect during EDM of composites due to the existence of more than one material phase constituents. Therefore, the present work aims to study and optimize the performance characteristics under various EDM conditions employed in making rectangular channels on AA6061-B4C composite material. Initially, AA6061-4wt.%B4C composites were fabricated by ultrasonically assisted stir-casting, and the improved properties were obtained from various mechanical characterizations. The EDM experiments were conducted according to the full factorial experimental design. The three levels of input conditions such as discharge Current (I), discharge duration (T On), and discharge idle time (T Off) were considered. The considered output responses are material removal rate (MRR),taper (θ) of the machined channel, tool wear rate (TWR), average surface roughness (R) of the machined surface, and average recast layer thickness (ARLT) of the machined zone. These responses are co-related with multi-objective types in the sense that the MRR has to be maximized with all other responses minimized. Hence, principal component analysis (PCA) coupled with grey relation analysis (GRA) was used for optimization in which the results were normalized, and all the responses were converted into a single response named weighted grey relation grade (WGRG) for each trial. The experimental trial, which had the highest WGRG, was considered as a local optimum. The global optimum parameters were obtained by performing the Taguchi method (TM) (higher-the-better) for the maximization of WGRG. The analysis of variance (ANOVA) was performed to know the contribution of each EDM parameter toward the WGRG. The optimum levels of Current, T On, and T Off were identified as 8 A, 25 µs, and 36 µs, respectively. Results showed that all three input parameters significantly affected the WGRG, and a higher contribution of Current (52.11%) followed by the T On (26.72%) was observed. The interaction between the Current and T Off was found to be greater than other interactions. Taper values were observed to be reduced at the combination of 8 A discharge Current and 25 µs T On. None of the input parameters significantly affected the Ra, except for Current, which showed a slight effect. ARLT values showed an increasing trend of T On from 25 µs to 45 µs but decreased slightly at 65 µs for all Current levels. The moderate Current level 6 A was observed to be favorable in reducing ARLT when compared to low (4 A) and high (8 A) for all Ton values.
{"title":"A comprehensive investigation on machining of composites by EDM for microfeatures and surface integrity","authors":"Suresh Gudipudi, Selvaraj Nagamuthu, Kanmani Subbu Subbian, Surya Prakasa Rao Chilakalapalli","doi":"10.1177/25165984211063308","DOIUrl":"https://doi.org/10.1177/25165984211063308","url":null,"abstract":"In electro-discharge machining (EDM), the material removal takes place by precisely controlled sparks that occur between tool and workpiece separated with a spark gap in the presence of a dielectric. Generally, the non-contacting type and less material removal rates are attributed to attain a good surface finish and close dimensional tolerances during an EDM of monolithic metals and alloys. But the dimensional accuracy and surface integrity parameters would considerably affect during EDM of composites due to the existence of more than one material phase constituents. Therefore, the present work aims to study and optimize the performance characteristics under various EDM conditions employed in making rectangular channels on AA6061-B4C composite material. Initially, AA6061-4wt.%B4C composites were fabricated by ultrasonically assisted stir-casting, and the improved properties were obtained from various mechanical characterizations. The EDM experiments were conducted according to the full factorial experimental design. The three levels of input conditions such as discharge Current (I), discharge duration (T On), and discharge idle time (T Off) were considered. The considered output responses are material removal rate (MRR),taper (θ) of the machined channel, tool wear rate (TWR), average surface roughness (R) of the machined surface, and average recast layer thickness (ARLT) of the machined zone. These responses are co-related with multi-objective types in the sense that the MRR has to be maximized with all other responses minimized. Hence, principal component analysis (PCA) coupled with grey relation analysis (GRA) was used for optimization in which the results were normalized, and all the responses were converted into a single response named weighted grey relation grade (WGRG) for each trial. The experimental trial, which had the highest WGRG, was considered as a local optimum. The global optimum parameters were obtained by performing the Taguchi method (TM) (higher-the-better) for the maximization of WGRG. The analysis of variance (ANOVA) was performed to know the contribution of each EDM parameter toward the WGRG. The optimum levels of Current, T On, and T Off were identified as 8 A, 25 µs, and 36 µs, respectively. Results showed that all three input parameters significantly affected the WGRG, and a higher contribution of Current (52.11%) followed by the T On (26.72%) was observed. The interaction between the Current and T Off was found to be greater than other interactions. Taper values were observed to be reduced at the combination of 8 A discharge Current and 25 µs T On. None of the input parameters significantly affected the Ra, except for Current, which showed a slight effect. ARLT values showed an increasing trend of T On from 25 µs to 45 µs but decreased slightly at 65 µs for all Current levels. The moderate Current level 6 A was observed to be favorable in reducing ARLT when compared to low (4 A) and high (8 A) for all Ton values.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124738357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-30DOI: 10.1177/25165984211058625
S. Singh, H. Mali, S. Suryawanshi, S. Singh
Microchannel heat dissipation devices were first conceptualized in 1981 and since then are at the forefront of cooling techniques for a variety of applications, extending from computer chips and turbine blades to lasers and optical systems. However, much of the research is concentrated on steady flow of a cooling fluid through the channels. In this article, transient two-dimensional (2D) simulation for heat transfer in microchannels under a pulsed-flow condition is carried out. For validation of simulation results, a novel heat sink device is designed and fabricated, using milling and micro-electric discharge machining (EDM) technique. The fabricated device is then tested to evaluate the effect of a variable flow rate on the heat transfer characteristics when the flow is pulsating. It is found that the numerical results underpredict slightly as compared to actual experimental results. Results indicate a higher temperature at the outlet of the heat sink device for lower pulse frequency, and as pulse frequency increases, the outlet temperature decreases.
{"title":"Pulsed-flow microchannel heat sink: Simulation and experimental validation","authors":"S. Singh, H. Mali, S. Suryawanshi, S. Singh","doi":"10.1177/25165984211058625","DOIUrl":"https://doi.org/10.1177/25165984211058625","url":null,"abstract":"Microchannel heat dissipation devices were first conceptualized in 1981 and since then are at the forefront of cooling techniques for a variety of applications, extending from computer chips and turbine blades to lasers and optical systems. However, much of the research is concentrated on steady flow of a cooling fluid through the channels. In this article, transient two-dimensional (2D) simulation for heat transfer in microchannels under a pulsed-flow condition is carried out. For validation of simulation results, a novel heat sink device is designed and fabricated, using milling and micro-electric discharge machining (EDM) technique. The fabricated device is then tested to evaluate the effect of a variable flow rate on the heat transfer characteristics when the flow is pulsating. It is found that the numerical results underpredict slightly as compared to actual experimental results. Results indicate a higher temperature at the outlet of the heat sink device for lower pulse frequency, and as pulse frequency increases, the outlet temperature decreases.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121703980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-12DOI: 10.1177/25165984211045201
R. Shukla, Gowtham Beera, A. Dubey, Varun Sharma, P. R. Sankar, R. Dhawan, P. Tiwari, A. Sinha
In the present work, a micro-electro-mechanical system (MEMS)-based electrostatic micromotor is designed and fabricated. Finite element analysis is done and various parameters affecting the torque are studied. Maximum torque is achieved at 120° phase angle. The effect of change in voltage, micromotor height and frequency is analysed and discussed. UV-SLIGA, a microfabrication technique, is used for the fabrication of electrostatic micromotor of height 30µm and higher. UV lithography is conducted by both positive AZ P4620 and negative (SU-8 10 and SU-8 2150) photoresists. Copper (Cu) is used as a sacrificial layer to release the rotor (the movable part) of the electrostatic micromotor. Electroformed nickel (Ni) is used for making stator, rotor and axle, whereas chromium (Cr) is used as a seed layer. The micromotor is fabricated with a stator-rotor pole having configuration ratio of 3:2. The gap between the rotor and axle is 20 µm. Wet chemical etching is used to etch the deposited metal layers (Cr, Ni and Cu). Challenges such as the adhesion between the photoresist mould and substrate, cracks, seepage and misalignment are faced during the microfabrication. These challenges are overcome by optimizing the various parameters. The fabrication of electrostatic micromotor is done successfully and the results are discussed in the article.
{"title":"Design analysis and fabrication of side-drive electrostatic micromotor by UV-SLIGA","authors":"R. Shukla, Gowtham Beera, A. Dubey, Varun Sharma, P. R. Sankar, R. Dhawan, P. Tiwari, A. Sinha","doi":"10.1177/25165984211045201","DOIUrl":"https://doi.org/10.1177/25165984211045201","url":null,"abstract":"In the present work, a micro-electro-mechanical system (MEMS)-based electrostatic micromotor is designed and fabricated. Finite element analysis is done and various parameters affecting the torque are studied. Maximum torque is achieved at 120° phase angle. The effect of change in voltage, micromotor height and frequency is analysed and discussed. UV-SLIGA, a microfabrication technique, is used for the fabrication of electrostatic micromotor of height 30µm and higher. UV lithography is conducted by both positive AZ P4620 and negative (SU-8 10 and SU-8 2150) photoresists. Copper (Cu) is used as a sacrificial layer to release the rotor (the movable part) of the electrostatic micromotor. Electroformed nickel (Ni) is used for making stator, rotor and axle, whereas chromium (Cr) is used as a seed layer. The micromotor is fabricated with a stator-rotor pole having configuration ratio of 3:2. The gap between the rotor and axle is 20 µm. Wet chemical etching is used to etch the deposited metal layers (Cr, Ni and Cu). Challenges such as the adhesion between the photoresist mould and substrate, cracks, seepage and misalignment are faced during the microfabrication. These challenges are overcome by optimizing the various parameters. The fabrication of electrostatic micromotor is done successfully and the results are discussed in the article.","PeriodicalId":129806,"journal":{"name":"Journal of Micromanufacturing","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129608780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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