Thanongsak Thepsonthi | Burapha University (original) (raw)

Papers by Thanongsak Thepsonthi

Research paper thumbnail of Finite element modeling and simulation of micro-milling

Research paper thumbnail of Modeling and optimization of micro-end milling process for micro-manufacturing

The miniaturization of devices has been under high demand since they offer added benefits such as... more The miniaturization of devices has been under high demand since they offer added benefits such as high mobility and portability, better accessibility and functionality, and lower energy consumption. Specific applications include energy devices such as heat sinks and exchangers, biomedical devices such as microfluidic devices, microneedles, and implants, automotive and aircraft components, and sensory devices. As the demand to produce such miniature products continue to increase, an imminent need for advanced manufacturing processes that can fabricate very small parts directly, cost effectively, and with high productivity arises. Micro-end milling is one of the most promising manufacturing processes capable of fabricating discrete parts with complex features in micro-scale (feature size < 1000 µm) due to its high flexibility for processing a wide range of materials with a low setup cost. However, micro-end milling process possesses several difficulties in precision fabrication of such products due to size effect, rapid tool wear, burr formation, tool and workpiece deflection, and premature tool breakage. In addition, these micro-products require tighter geometrical tolerances and iii better surface quality. These difficulties and requirements make the selection of process parameters for high performance micro-end milling very challenging. In this research, we conducted experimental and numerical modeling studies and multi-objective process optimization for micro-end milling. An extensive study of process parameters such as tool coatings, cutting velocity, feed rate, and axial depth of cut was performed in order to understand the effects of these parameters on the performance of micro-end milling process. Novel finite element based process models in 2-D and 3-D have been developed. Both experimental models and finite element based process simulations were utilized to construct various predictive models for the process outputs. These predictive models include physics-based outputs such as chip deformations, tool forces and temperatures, tool wear rate and depth, as well as performance related measures such as surface finish, burr formation, and tool life. Furthermore, we developed a comprehensive decision support system by using the predictive models which can facilitate a selection of process parameters and toolpath strategies based on desired performances. Multi-objective optimization studies were conducted by utilizing predictive models for obtaining optimal decision variable sets. Moreover, this research also demonstrates the current capabilities of micro-end milling in fabricating micro-products such as heat sinks in brass and implants in titanium alloys, and micro-needles in polymers.

Research paper thumbnail of Micro milling of titanium alloy Ti-6Al-4V: 3-D finite element modeling for prediction of chip flow and burr formation

Production Engineering, 2017

Research paper thumbnail of Simulation of serrated chip formation in micro-milling of titanium alloy Ti-6Al-4V using 2D elasto-viscoplastic finite element modeling

Production Engineering, 2016

Finite element simulations have been utilized in analyses of machining process for several decade... more Finite element simulations have been utilized in analyses of machining process for several decades. In mechanical micromachining, finite element simulation can also be used for predicting cutting forces, minimal chip thickness, temperatures, and tool wear. The accuracy of results and the computational cost are highly dependent upon the assumptions which govern that particular chip formation problem. This study presents a comparison of two different material assumptions in finite element simulation of micro-milling titanium alloy Ti-6Al-4V. The same simulation was conducted by using the elasto-viscoplastic and the viscoplastic material assumptions. The predicted results are compared against the experimental observations. The results have shown that the material assumption has a major effect on the mechanism of chip formation and heat generation but a minor effect on the cutting force and tool wear prediction. In terms of computational cost, it was found that the simulation with the viscoplastic material assumption can reduce simulation time up to eight times that of required for a simulation with elasto-viscoplastic assumption.

Research paper thumbnail of 3-D finite element process simulation of micro-end milling Ti-6Al-4V titanium alloy: Experimental validations on chip flow and tool wear

Journal of Materials Processing Technology, 2015

Finite Element (FE) simulation of machining can be used as a replacement or a supplementary to th... more Finite Element (FE) simulation of machining can be used as a replacement or a supplementary to the physical experiment allowing an analysis to be performed at a lower cost. Besides, FE simulation can offer predictions of process variables which are difficult to obtain by experiment. This paper provides investigations on 3-D FE modeling and simulation of micro-end milling process for Ti-6Al-4V titanium alloy. 3-D FE models proposed for full-immersion, half immersion up and down milling are utilized to study the influence of increasing tool edge radius due to wear on the process performance of micro-end milling. Predicted 3-D chip flow and shapes are compared against the experiments which provided reasonably good agreements. Tool wear along the micro-end milling tool is predicted and validated with experiments. The results of this study indicated that tool wear has a significant impact to the cutting force, cutting temperature, tool wear rate, chip flow and burr formation. In addition, a comparison of 3-D and 2-D FE simulations is provided giving a better understanding of utilizing their predictions.

Research paper thumbnail of Pulsed Laser Assisted Exfoliation of Hydrogen Ion Implanted Single Crystalline SiC Thin Layers

Research paper thumbnail of An integrated toolpath and process parameter optimization for high-performance micro-milling process of Ti–6Al–4V titanium alloy

The International Journal of Advanced Manufacturing Technology, 2014

Titanium alloys such as Ti-6Al-4V offer biocompatibility, corrosion resistance, and superb mechan... more Titanium alloys such as Ti-6Al-4V offer biocompatibility, corrosion resistance, and superb mechanical properties and are considered the most important metallic biomaterial for medical applications. However, mechanical machining of titanium alloys is still highly difficult and even more challenging for micro-scale machining such as micro-milling. Severe burr formation and rapid tool wear create significant problems such as poor surface roughness. In order to improve the performance of micro-milling Ti-6Al-4V alloy, this study proposes an integrated method in selecting the toolpath and optimum process parameters which can meet micromachining requirements and constraints. Controlled microend-milling experiments for measuring burr formation and surface roughness, finite element simulations for predicting forces and tool wear, and mathematical modeling and optimization techniques have been utilized for determining optimum toolpath strategy and process parameters. Based on the microend-milling tests on a circular thin rib feature, process optimization results are validated and indicate a significant improvement in process performances in terms of minimizing burr formation, maximizing tool life, and surface quality.

Research paper thumbnail of Nanosecond Pulsed Laser Processing of Ion Implanted Single Crystal Silicon Carbide Thin Layers

Physics Procedia, 2014

The attractiveness of single crystal SiC in a variety of high power, high voltage, and high tempe... more The attractiveness of single crystal SiC in a variety of high power, high voltage, and high temperature device applications such as electric vehicles and jet engines is counteracted by the very high cost of substrates. Precision cutting of multiple micrometre thick SiC layers and transferring them to lower cost substrates would drive the cost down and allow expanding the use of single crystal SiC. In this study, laser beam processing has been utilized to exfoliate thin layers from a surface of single crystal SiC that was prepared with hydrogen and boron ion implantation. The layer thickness of 1 μm has been achieved by ion implantation that formed voids and microcracks under the surface at a layer of 150 nm thick. High energy laser pulses provided the layer removal and its transfer to bonded Si substrate has been shown. Exfoliated surfaces and topography have been evaluated with Scanning Electron Microscopy. Furthermore, thermal modelling of pulse laser irradiation of implanted multi-layer SiC material has been conducted and temperature profiles are obtained at different peak pulse intensity settings to optimize exfoliation process parameters. It was found that laser exfoliation mechanism can be further improved by higher optical absorptance of defect rich layer obtained with boron ion implantation.

Research paper thumbnail of Mechanical Micro-Machining

Design and Manufacturing of Micro-Products, 2011

ABSTRACT Export Date: 3 February 2014, Source: Scopus, Language of Original Document: English, Co... more ABSTRACT Export Date: 3 February 2014, Source: Scopus, Language of Original Document: English, Correspondence Address: Özel, T.; School of Engineering, Industrial and Systems Engineering, Rutgers University, Piscataway NJ, United States, References: Madou, M., Fundamentals of microfabrication (1997) Boca Raton (FL): CRC Press;;

Research paper thumbnail of Micromilling high aspect ratio features using tungsten carbide tools

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2014

This article presents experimental studies on micromilling thin walls to explore process capabili... more This article presents experimental studies on micromilling thin walls to explore process capabilities in direct manufacturing of high aspect ratio features using tungsten carbide micro-end milling tools for two different materials: aluminium and brass. This study has been conducted in two phases. At first, the effects of micromilling parameters on the surface roughness have been investigated and most suitable machining conditions in obtaining highest surface quality have been identified. In the second phase, the effects of machining strategies have been explored in order to optimize final quality of the thin walls in terms of straightness of the machined thin walls, uniformity of wall thickness and burr presence. As a result of this experimental study, optimized machining parameters and strategies are presented. In the case of micromilling brass (CuZn36Pb3), a down-milling cutting direction with a Z-step milling strategy at a spindle speed of 35,000 r min−1, an axial depth of cut of...

Research paper thumbnail of Swarm Intelligent Selection and Optimization of Machining System Parameters for Microchannel Fabrication in Medical Devices

Materials and Manufacturing Processes, 2011

Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf ... more Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

Research paper thumbnail of Experimental and finite element simulation based investigations on micro-milling Ti-6Al-4V titanium alloy: Effects of cBN coating on tool wear

Journal of Materials Processing Technology, 2013

Micro-milling process is a direct and flexible fabrication method in producing functional three d... more Micro-milling process is a direct and flexible fabrication method in producing functional three dimensional micro-products. The advance of micro-milling process ultimately depends on the development of micro cutting tools since it is a tool-based process. Therefore, in this study an attempt to improve the performance of carbide micro-end mills by applying cubic boron nitride (cBN) coating was carried out. Experiments and finite element method (FEM) based simulations were used to study the effect of cBN coated tool in micro-machining of Ti-6Al-4V titanium alloy. The experiments were conducted to compare the performance of cBN coated and uncoated micro-end mills in terms of surface roughness, burr formation and tool wear. FE simulations were employed to investigate chip formation process in micro-milling to reveal the effects of cBN coated micro-end mills with increased edge radius in terms of cutting force generation, tool temperature and contact pressure, sliding velocity and hence tool wear rate. The simulation results were further utilized for estimating tool life using a sliding wear rate model and compared with experiments. This study clearly showed that the cBN coated carbide tool outperformed the uncoated carbide tool in generation of tool wear and cutting temperature.

Research paper thumbnail of Nanosecond pulsed laser micromachining of PMMA-based microfluidic channels

Journal of Manufacturing Processes, 2012

This paper reports an investigation into the effects of nanosecond laser processing parameters on... more This paper reports an investigation into the effects of nanosecond laser processing parameters on the geometry of microchannels fabricated from polymethylmethacrylate (PMMA). The Nd:YAG solidstate pulsed laser has a wavelength of 1064 nm and a measured maximum power of 4.15 W. The laser processing parameters are varied in a scanning speed range of 400-800 pulses/mm, a pulse frequency range of 5-11 Hz, a Q-switch delay time range of 170-180 s. Main effects plots and microchannel images are utilized to identify the effects of the process parameters for improving material removal rate and surface quality simultaneously for laser micromachining of microchannels in PMMA polymer. It is observed that channel width and depth decreased linearly with increasing Q-switch delay time (hence average power) and increased non-linearly with higher scanning rates and not much affected by the increase in pulse frequency.

Research paper thumbnail of Investigation into minimal-cutting-fluid application in high-speed milling of hardened steel using carbide mills

International Journal of Machine Tools and Manufacture, 2009

ABSTRACT

Research paper thumbnail of Effect of process parameters in nanosecond pulsed laser micromachining of PMMA-based microchannels at near-infrared and ultraviolet wavelengths

The International Journal of Advanced Manufacturing Technology, 2012

ABSTRACT This paper presents investigations on the effects of nanosecond laser processing paramet... more ABSTRACT This paper presents investigations on the effects of nanosecond laser processing parameters on depth and width of microchannels fabricated from polymethylmethacrylate (PMMA) polymer. A neodymium-doped yttrium aluminium garnet pulsed laser with a fundamental wavelength of 1,064 nm and a third harmonic wavelength of 355 nm with pulse duration of 5 ns is utilized. Hence, experiments are conducted at near-infrared (NIR) and ultraviolet (UV) wavelengths. The laser processing parameters of pulse energy (402–415 mJ at NIR and 35–73 mJ at UV wavelengths), pulse frequency (8–11 Hz), focal spot size (140–190 μm at NIR and 75 μm at UV wavelengths) and scanning rate (400–800 pulse/mm at NIR and 101–263 pulse/mm at UV wavelengths) are varied to obtain a wide range of fluence and processing rate. Microchannel width and depth profile are measured, and main effects plots are obtained to identify the effects of process parameters on channel geometry (width and depth) and material removal rate. The relationship between process variables (width and depth of laser-ablated microchannels) and process parameters is investigated. It is observed that channel width (140–430 μm at NIR and 100–150 μm at UV wavelengths) and depth (30–120 μm at NIR and 35–75 μm at UV wavelengths) decreased linearly with increasing fluence and increased non-linearly with increasing scanning rate. It is also observed that laser processing at UV wavelength provided more consistent channel profiles at lower fluences due to higher laser absorption of PMMA at this wavelength. Mathematical modeling for predicting microchannel profile was developed and validated with experimental results obtained with pulsed laser micromachining at NIR and UV wavelengths.

Research paper thumbnail of Experiments and finite element simulations on micro-milling of Ti–6Al–4V alloy with uncoated and cBN coated micro-tools

Research paper thumbnail of Machining Applications

Research paper thumbnail of Finite Element Simulation of Micro-End Milling Titanium Alloy: Comparison of Viscoplastic and Elasto-Viscoplastic Models

Research paper thumbnail of Statistically based process optimization for improved surface quality in micro-end milling of Ti-6Al- 4V titanium alloy

Conference code: 87183, Export Date: 3 February 2014, Source: Scopus, Language of Original Docume... more Conference code: 87183, Export Date: 3 February 2014, Source: Scopus, Language of Original Document: English, Correspondence Address: Thepsonthi, T.; Manufacturing Automation Research Laboratory, Department of Industrial and Systems Engineering, Rutgers University, Piscataway, NJ, United States, References: Aramcharoen, A., Mativenga, P.T., Size effect and tool geometry in micromilling of tool steel (2009) Precision Engineering, 33 (4), pp. 402-407;, Sponsors: North American Manufacturing Research Institution (NAMRI) of SME; Oregon Nanoscience and Microtechnologies Institute (ONAMI); Oregon State University (OSU) - College of Engineering; GE; Aerotech

Research paper thumbnail of Sensor-Assisted Monitoring and Optimization of Process Parameters in Micro-end Milling of Ti-6Al-4V Titanium Alloy

Micro-end milling is one of the promising methods for rapid fabrication of medical devices and im... more Micro-end milling is one of the promising methods for rapid fabrication of medical devices and implants with 3D complex shapes. However, controlling the micro-end milling process to obtaining the desired results is much challenging compared to that of macro-end milling due to the size effect and some uncontrollable factors. The problem is much pronounced when workpiece material is a difficult-to-process material such as Titanium alloys which are widely used as material of choice for small medical devices and implants. Therefore, in this study the feasibility of using acoustic emission (AE) signal to monitor and optimize surface generation in micro-end milling of Ti-6Al-4V was investigated. The results revealed that the mean, deviation and density of AE signal sensitively change in respond to a change in cutting parameters and generation of machined surface. Therefore, monitoring or predicting surface generation and burr formation in micro-end milling process is feasible by using of ...

Research paper thumbnail of Finite element modeling and simulation of micro-milling

Research paper thumbnail of Modeling and optimization of micro-end milling process for micro-manufacturing

The miniaturization of devices has been under high demand since they offer added benefits such as... more The miniaturization of devices has been under high demand since they offer added benefits such as high mobility and portability, better accessibility and functionality, and lower energy consumption. Specific applications include energy devices such as heat sinks and exchangers, biomedical devices such as microfluidic devices, microneedles, and implants, automotive and aircraft components, and sensory devices. As the demand to produce such miniature products continue to increase, an imminent need for advanced manufacturing processes that can fabricate very small parts directly, cost effectively, and with high productivity arises. Micro-end milling is one of the most promising manufacturing processes capable of fabricating discrete parts with complex features in micro-scale (feature size < 1000 µm) due to its high flexibility for processing a wide range of materials with a low setup cost. However, micro-end milling process possesses several difficulties in precision fabrication of such products due to size effect, rapid tool wear, burr formation, tool and workpiece deflection, and premature tool breakage. In addition, these micro-products require tighter geometrical tolerances and iii better surface quality. These difficulties and requirements make the selection of process parameters for high performance micro-end milling very challenging. In this research, we conducted experimental and numerical modeling studies and multi-objective process optimization for micro-end milling. An extensive study of process parameters such as tool coatings, cutting velocity, feed rate, and axial depth of cut was performed in order to understand the effects of these parameters on the performance of micro-end milling process. Novel finite element based process models in 2-D and 3-D have been developed. Both experimental models and finite element based process simulations were utilized to construct various predictive models for the process outputs. These predictive models include physics-based outputs such as chip deformations, tool forces and temperatures, tool wear rate and depth, as well as performance related measures such as surface finish, burr formation, and tool life. Furthermore, we developed a comprehensive decision support system by using the predictive models which can facilitate a selection of process parameters and toolpath strategies based on desired performances. Multi-objective optimization studies were conducted by utilizing predictive models for obtaining optimal decision variable sets. Moreover, this research also demonstrates the current capabilities of micro-end milling in fabricating micro-products such as heat sinks in brass and implants in titanium alloys, and micro-needles in polymers.

Research paper thumbnail of Micro milling of titanium alloy Ti-6Al-4V: 3-D finite element modeling for prediction of chip flow and burr formation

Production Engineering, 2017

Research paper thumbnail of Simulation of serrated chip formation in micro-milling of titanium alloy Ti-6Al-4V using 2D elasto-viscoplastic finite element modeling

Production Engineering, 2016

Finite element simulations have been utilized in analyses of machining process for several decade... more Finite element simulations have been utilized in analyses of machining process for several decades. In mechanical micromachining, finite element simulation can also be used for predicting cutting forces, minimal chip thickness, temperatures, and tool wear. The accuracy of results and the computational cost are highly dependent upon the assumptions which govern that particular chip formation problem. This study presents a comparison of two different material assumptions in finite element simulation of micro-milling titanium alloy Ti-6Al-4V. The same simulation was conducted by using the elasto-viscoplastic and the viscoplastic material assumptions. The predicted results are compared against the experimental observations. The results have shown that the material assumption has a major effect on the mechanism of chip formation and heat generation but a minor effect on the cutting force and tool wear prediction. In terms of computational cost, it was found that the simulation with the viscoplastic material assumption can reduce simulation time up to eight times that of required for a simulation with elasto-viscoplastic assumption.

Research paper thumbnail of 3-D finite element process simulation of micro-end milling Ti-6Al-4V titanium alloy: Experimental validations on chip flow and tool wear

Journal of Materials Processing Technology, 2015

Finite Element (FE) simulation of machining can be used as a replacement or a supplementary to th... more Finite Element (FE) simulation of machining can be used as a replacement or a supplementary to the physical experiment allowing an analysis to be performed at a lower cost. Besides, FE simulation can offer predictions of process variables which are difficult to obtain by experiment. This paper provides investigations on 3-D FE modeling and simulation of micro-end milling process for Ti-6Al-4V titanium alloy. 3-D FE models proposed for full-immersion, half immersion up and down milling are utilized to study the influence of increasing tool edge radius due to wear on the process performance of micro-end milling. Predicted 3-D chip flow and shapes are compared against the experiments which provided reasonably good agreements. Tool wear along the micro-end milling tool is predicted and validated with experiments. The results of this study indicated that tool wear has a significant impact to the cutting force, cutting temperature, tool wear rate, chip flow and burr formation. In addition, a comparison of 3-D and 2-D FE simulations is provided giving a better understanding of utilizing their predictions.

Research paper thumbnail of Pulsed Laser Assisted Exfoliation of Hydrogen Ion Implanted Single Crystalline SiC Thin Layers

Research paper thumbnail of An integrated toolpath and process parameter optimization for high-performance micro-milling process of Ti–6Al–4V titanium alloy

The International Journal of Advanced Manufacturing Technology, 2014

Titanium alloys such as Ti-6Al-4V offer biocompatibility, corrosion resistance, and superb mechan... more Titanium alloys such as Ti-6Al-4V offer biocompatibility, corrosion resistance, and superb mechanical properties and are considered the most important metallic biomaterial for medical applications. However, mechanical machining of titanium alloys is still highly difficult and even more challenging for micro-scale machining such as micro-milling. Severe burr formation and rapid tool wear create significant problems such as poor surface roughness. In order to improve the performance of micro-milling Ti-6Al-4V alloy, this study proposes an integrated method in selecting the toolpath and optimum process parameters which can meet micromachining requirements and constraints. Controlled microend-milling experiments for measuring burr formation and surface roughness, finite element simulations for predicting forces and tool wear, and mathematical modeling and optimization techniques have been utilized for determining optimum toolpath strategy and process parameters. Based on the microend-milling tests on a circular thin rib feature, process optimization results are validated and indicate a significant improvement in process performances in terms of minimizing burr formation, maximizing tool life, and surface quality.

Research paper thumbnail of Nanosecond Pulsed Laser Processing of Ion Implanted Single Crystal Silicon Carbide Thin Layers

Physics Procedia, 2014

The attractiveness of single crystal SiC in a variety of high power, high voltage, and high tempe... more The attractiveness of single crystal SiC in a variety of high power, high voltage, and high temperature device applications such as electric vehicles and jet engines is counteracted by the very high cost of substrates. Precision cutting of multiple micrometre thick SiC layers and transferring them to lower cost substrates would drive the cost down and allow expanding the use of single crystal SiC. In this study, laser beam processing has been utilized to exfoliate thin layers from a surface of single crystal SiC that was prepared with hydrogen and boron ion implantation. The layer thickness of 1 μm has been achieved by ion implantation that formed voids and microcracks under the surface at a layer of 150 nm thick. High energy laser pulses provided the layer removal and its transfer to bonded Si substrate has been shown. Exfoliated surfaces and topography have been evaluated with Scanning Electron Microscopy. Furthermore, thermal modelling of pulse laser irradiation of implanted multi-layer SiC material has been conducted and temperature profiles are obtained at different peak pulse intensity settings to optimize exfoliation process parameters. It was found that laser exfoliation mechanism can be further improved by higher optical absorptance of defect rich layer obtained with boron ion implantation.

Research paper thumbnail of Mechanical Micro-Machining

Design and Manufacturing of Micro-Products, 2011

ABSTRACT Export Date: 3 February 2014, Source: Scopus, Language of Original Document: English, Co... more ABSTRACT Export Date: 3 February 2014, Source: Scopus, Language of Original Document: English, Correspondence Address: Özel, T.; School of Engineering, Industrial and Systems Engineering, Rutgers University, Piscataway NJ, United States, References: Madou, M., Fundamentals of microfabrication (1997) Boca Raton (FL): CRC Press;;

Research paper thumbnail of Micromilling high aspect ratio features using tungsten carbide tools

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2014

This article presents experimental studies on micromilling thin walls to explore process capabili... more This article presents experimental studies on micromilling thin walls to explore process capabilities in direct manufacturing of high aspect ratio features using tungsten carbide micro-end milling tools for two different materials: aluminium and brass. This study has been conducted in two phases. At first, the effects of micromilling parameters on the surface roughness have been investigated and most suitable machining conditions in obtaining highest surface quality have been identified. In the second phase, the effects of machining strategies have been explored in order to optimize final quality of the thin walls in terms of straightness of the machined thin walls, uniformity of wall thickness and burr presence. As a result of this experimental study, optimized machining parameters and strategies are presented. In the case of micromilling brass (CuZn36Pb3), a down-milling cutting direction with a Z-step milling strategy at a spindle speed of 35,000 r min−1, an axial depth of cut of...

Research paper thumbnail of Swarm Intelligent Selection and Optimization of Machining System Parameters for Microchannel Fabrication in Medical Devices

Materials and Manufacturing Processes, 2011

Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf ... more Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

Research paper thumbnail of Experimental and finite element simulation based investigations on micro-milling Ti-6Al-4V titanium alloy: Effects of cBN coating on tool wear

Journal of Materials Processing Technology, 2013

Micro-milling process is a direct and flexible fabrication method in producing functional three d... more Micro-milling process is a direct and flexible fabrication method in producing functional three dimensional micro-products. The advance of micro-milling process ultimately depends on the development of micro cutting tools since it is a tool-based process. Therefore, in this study an attempt to improve the performance of carbide micro-end mills by applying cubic boron nitride (cBN) coating was carried out. Experiments and finite element method (FEM) based simulations were used to study the effect of cBN coated tool in micro-machining of Ti-6Al-4V titanium alloy. The experiments were conducted to compare the performance of cBN coated and uncoated micro-end mills in terms of surface roughness, burr formation and tool wear. FE simulations were employed to investigate chip formation process in micro-milling to reveal the effects of cBN coated micro-end mills with increased edge radius in terms of cutting force generation, tool temperature and contact pressure, sliding velocity and hence tool wear rate. The simulation results were further utilized for estimating tool life using a sliding wear rate model and compared with experiments. This study clearly showed that the cBN coated carbide tool outperformed the uncoated carbide tool in generation of tool wear and cutting temperature.

Research paper thumbnail of Nanosecond pulsed laser micromachining of PMMA-based microfluidic channels

Journal of Manufacturing Processes, 2012

This paper reports an investigation into the effects of nanosecond laser processing parameters on... more This paper reports an investigation into the effects of nanosecond laser processing parameters on the geometry of microchannels fabricated from polymethylmethacrylate (PMMA). The Nd:YAG solidstate pulsed laser has a wavelength of 1064 nm and a measured maximum power of 4.15 W. The laser processing parameters are varied in a scanning speed range of 400-800 pulses/mm, a pulse frequency range of 5-11 Hz, a Q-switch delay time range of 170-180 s. Main effects plots and microchannel images are utilized to identify the effects of the process parameters for improving material removal rate and surface quality simultaneously for laser micromachining of microchannels in PMMA polymer. It is observed that channel width and depth decreased linearly with increasing Q-switch delay time (hence average power) and increased non-linearly with higher scanning rates and not much affected by the increase in pulse frequency.

Research paper thumbnail of Investigation into minimal-cutting-fluid application in high-speed milling of hardened steel using carbide mills

International Journal of Machine Tools and Manufacture, 2009

ABSTRACT

Research paper thumbnail of Effect of process parameters in nanosecond pulsed laser micromachining of PMMA-based microchannels at near-infrared and ultraviolet wavelengths

The International Journal of Advanced Manufacturing Technology, 2012

ABSTRACT This paper presents investigations on the effects of nanosecond laser processing paramet... more ABSTRACT This paper presents investigations on the effects of nanosecond laser processing parameters on depth and width of microchannels fabricated from polymethylmethacrylate (PMMA) polymer. A neodymium-doped yttrium aluminium garnet pulsed laser with a fundamental wavelength of 1,064 nm and a third harmonic wavelength of 355 nm with pulse duration of 5 ns is utilized. Hence, experiments are conducted at near-infrared (NIR) and ultraviolet (UV) wavelengths. The laser processing parameters of pulse energy (402–415 mJ at NIR and 35–73 mJ at UV wavelengths), pulse frequency (8–11 Hz), focal spot size (140–190 μm at NIR and 75 μm at UV wavelengths) and scanning rate (400–800 pulse/mm at NIR and 101–263 pulse/mm at UV wavelengths) are varied to obtain a wide range of fluence and processing rate. Microchannel width and depth profile are measured, and main effects plots are obtained to identify the effects of process parameters on channel geometry (width and depth) and material removal rate. The relationship between process variables (width and depth of laser-ablated microchannels) and process parameters is investigated. It is observed that channel width (140–430 μm at NIR and 100–150 μm at UV wavelengths) and depth (30–120 μm at NIR and 35–75 μm at UV wavelengths) decreased linearly with increasing fluence and increased non-linearly with increasing scanning rate. It is also observed that laser processing at UV wavelength provided more consistent channel profiles at lower fluences due to higher laser absorption of PMMA at this wavelength. Mathematical modeling for predicting microchannel profile was developed and validated with experimental results obtained with pulsed laser micromachining at NIR and UV wavelengths.

Research paper thumbnail of Experiments and finite element simulations on micro-milling of Ti–6Al–4V alloy with uncoated and cBN coated micro-tools

Research paper thumbnail of Machining Applications

Research paper thumbnail of Finite Element Simulation of Micro-End Milling Titanium Alloy: Comparison of Viscoplastic and Elasto-Viscoplastic Models

Research paper thumbnail of Statistically based process optimization for improved surface quality in micro-end milling of Ti-6Al- 4V titanium alloy

Conference code: 87183, Export Date: 3 February 2014, Source: Scopus, Language of Original Docume... more Conference code: 87183, Export Date: 3 February 2014, Source: Scopus, Language of Original Document: English, Correspondence Address: Thepsonthi, T.; Manufacturing Automation Research Laboratory, Department of Industrial and Systems Engineering, Rutgers University, Piscataway, NJ, United States, References: Aramcharoen, A., Mativenga, P.T., Size effect and tool geometry in micromilling of tool steel (2009) Precision Engineering, 33 (4), pp. 402-407;, Sponsors: North American Manufacturing Research Institution (NAMRI) of SME; Oregon Nanoscience and Microtechnologies Institute (ONAMI); Oregon State University (OSU) - College of Engineering; GE; Aerotech

Research paper thumbnail of Sensor-Assisted Monitoring and Optimization of Process Parameters in Micro-end Milling of Ti-6Al-4V Titanium Alloy

Micro-end milling is one of the promising methods for rapid fabrication of medical devices and im... more Micro-end milling is one of the promising methods for rapid fabrication of medical devices and implants with 3D complex shapes. However, controlling the micro-end milling process to obtaining the desired results is much challenging compared to that of macro-end milling due to the size effect and some uncontrollable factors. The problem is much pronounced when workpiece material is a difficult-to-process material such as Titanium alloys which are widely used as material of choice for small medical devices and implants. Therefore, in this study the feasibility of using acoustic emission (AE) signal to monitor and optimize surface generation in micro-end milling of Ti-6Al-4V was investigated. The results revealed that the mean, deviation and density of AE signal sensitively change in respond to a change in cutting parameters and generation of machined surface. Therefore, monitoring or predicting surface generation and burr formation in micro-end milling process is feasible by using of ...