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Lee H, Kim J, Lee S, Park J, Park J, Kim J. Effect of Coating Thickness on Abrasion and Cutting Performance of NCD-Coated Ball Endmills on Graphite Machining. MICROMACHINES 2023; 14:664. [PMID: 36985071 PMCID: PMC10054475 DOI: 10.3390/mi14030664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 06/18/2023]
Abstract
Nano-crystalline diamond (NCD) coating to improve the performance of cutting tools, as the coating thickness varies, the cutting performance and lifespan of the tool varies because the radius of its cutting edge and coating surface roughness are altered. Therefore, an in-depth analysis on the impact of the variations in coating thickness on the cutting tool abrasion and quality of machined surface is necessary. In this study, two NCD ball endmills were coated with 8 and 12 μm thicknesses, and the tool abrasion and roughness of the machined plane were observed after milling. Furthermore, the morphology of the coated surface and abrased cutting edge were observed using a 3D confocal microscope. Consequently, we observed that individual nodules were formed on the continuous aggregates as the coating thickness increased, which increased the coated surface roughness. The two damage modes of the aggregation determined the dominant abrasion that occurred on the cutting edges of both types of coating thicknesses. Delamination and crater wear caused a sharp increase in the roughness of the machined surface. In summary, the increase in coating thickness delayed the delamination of the coating but increased the roughness of the cutting edge, which reduced the machined surface roughness.
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Affiliation(s)
- Hyeonhwa Lee
- Molding & Metal Forming R&D Department, Korea Institute of Industrial Technology, Bucheon 14441, Republic of Korea
| | - Jinsoo Kim
- Molding & Metal Forming R&D Department, Korea Institute of Industrial Technology, Bucheon 14441, Republic of Korea
| | - Sungcheul Lee
- Department of Ultra-Precision Machines and Systems, Korea Institute of Machinery & Material, Daejeon 34103, Republic of Korea
| | - Jongeun Park
- Department of Mechanical Engineering, The State University of New York, Korea (SUNY Korea), Incheon 21985, Republic of Korea
| | - Jeongyeon Park
- Molding & Metal Forming R&D Department, Korea Institute of Industrial Technology, Bucheon 14441, Republic of Korea
| | - Jongsu Kim
- Molding & Metal Forming R&D Department, Korea Institute of Industrial Technology, Bucheon 14441, Republic of Korea
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Lee H, Kim J, Park J, Kim J. Analysis of Tool Wear and Roughness of Graphite Surfaces Machined Using MCD and NCD-Coated Ball Endmills. MICROMACHINES 2022; 13:mi13050766. [PMID: 35630233 PMCID: PMC9147727 DOI: 10.3390/mi13050766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/03/2022] [Accepted: 05/11/2022] [Indexed: 02/04/2023]
Abstract
The high-purity G5 graphite material is widely used for glass moulding and provides high hardness and brittleness because it is sintered to fine particles unlike other graphite materials. Hence, tool cutting of a G5 workpiece is performed by local fracture instead of plastic deformation of the machined surface. Although a diamond-coated tool with outstanding hardness is used to machine very hard graphite, the tool shows variability regarding the service life and machining performance depending on the grain size, even in the same machining environment. We investigated the wear and change trend of machined surface roughness considering microcrystalline diamond (MCD) and nanocrystalline diamond (NCD)-coated tools, which are generally used to machine graphite materials, and analysed their relation with coating. For rough machining, the MCD-coated tool, for which the delamination of coating occurred later, showed less wear and improved machined surface roughness. For precision machining, the NCD tool showed less tool wear rate relative to the cutting length, leading to a small difference in the machined surface roughness between the two tools. We conclude that if rough and precision machining processes are performed using the same cutting tool, the MCD-coated tool is advantageous in terms of service life, while the difference in roughness of the final machined surface between the tools is negligible.
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Affiliation(s)
| | | | | | - Jongsu Kim
- Correspondence: ; Tel.: +82-32-670-3935; Fax: +82-32-670-3920
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Experimental Study on Micro-Grinding of Ceramics for Micro-Structuring. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11178119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study, micro-grinding was performed to investigate the machining characteristics of alumina and zirconia. The machining of ceramics remains highly challenging owing to their properties, such as high brittleness and wear resistance, which leads to a shorter tool life and high machining costs. Polycrystalline diamond (PCD) was selected as the tool material, as it is suitable for machining hard and brittle materials, and micro-electrical discharge machining (EDM) was used to fabricate PCD micro-tools. When using a resistor-capacitor generator circuit in micro-EDM, the discharging energy is related to the working capacitance, and by controlling the working capacitance, the different edge radii and the surface roughness of the tool can be easily achieved. The feed rate, depth of cut, and rotation speed were set as experimental parameters to investigate the grinding characteristics of the ceramics. During the experiment, the grinding force and roughness of the bottom surface were monitored, and the roughness of the machined surfaces was measured using a three-dimensional surface profiler. A working capacitance of 1000 pF was used to fabricate a tool with an edge radius of 3.5 µm. The lower radius of the tool edge resulted in a decrease of the cutting force by 50% at most and a surface roughness of 19 nm Ra.
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O’Toole L, Kang CW, Fang FZ. Precision micro-milling process: state of the art. ADVANCES IN MANUFACTURING 2021; 9:173-205. [PMID: 34777895 PMCID: PMC8550556 DOI: 10.1007/s40436-020-00323-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/11/2020] [Accepted: 08/30/2020] [Indexed: 05/19/2023]
Abstract
Micro-milling is a precision manufacturing process with broad applications across the biomedical, electronics, aerospace, and aeronautical industries owing to its versatility, capability, economy, and efficiency in a wide range of materials. In particular, the micro-milling process is highly suitable for very precise and accurate machining of mold prototypes with high aspect ratios in the microdomain, as well as for rapid micro-texturing and micro-patterning, which will have great importance in the near future in bio-implant manufacturing. This is particularly true for machining of typical difficult-to-machine materials commonly found in both the mold and orthopedic implant industries. However, inherent physical process constraints of machining arise as macro-milling is scaled down to the microdomain. This leads to some physical phenomena during micro-milling such as chip formation, size effect, and process instabilities. These dynamic physical process phenomena are introduced and discussed in detail. It is important to remember that these phenomena have multifactor effects during micro-milling, which must be taken into consideration to maximize the performance of the process. The most recent research on the micro-milling process inputs is discussed in detail from a process output perspective to determine how the process as a whole can be improved. Additionally, newly developed processes that combine conventional micro-milling with other technologies, which have great prospects in reducing the issues related to the physical process phenomena, are also introduced. Finally, the major applications of this versatile precision machining process are discussed with important insights into how the application range may be further broadened.
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Affiliation(s)
- Lorcan O’Toole
- Center of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin 4, Ireland
| | - Cheng-Wei Kang
- Center of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin 4, Ireland
| | - Feng-Zhou Fang
- Center of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin 4, Ireland
- State Key Laboratory of Precision Measuring Technology and Instruments, Center of Micro/Nano Manufacturing Technology (MNMT), Tianjin University, Tianjin, 300072 People’s Republic of China
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Savkovic B, Kovac P, Dudic B, Gregus M, Rodic D, Strbac B, Ducic N. Comparative Characteristics of Ductile Iron and Austempered Ductile Iron Modeled by Neural Network. MATERIALS 2019; 12:ma12182864. [PMID: 31491929 PMCID: PMC6765992 DOI: 10.3390/ma12182864] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 09/01/2019] [Accepted: 09/02/2019] [Indexed: 11/16/2022]
Abstract
Experimental research of cutting force components during dry face milling operations are presented in the paper. The study was provided when milling of ductile cast iron alloyed with copper and its austempered ductile iron after the proper austempering process. In the study, virtual instrumentation designed for cutting forces components monitoring was used. During the research, orthogonal cutting forces components versus time were monitored and relationship of cutting forces components versus speed, feed and depth of cut were determined by artificial neural network and response surface methodology. An analysis was made regarding the consistency of the measured cutting forces and the values obtained from the model supported by an artificial neural network for the investigated interval of the cutting regime. Based on the results, an analysis of the feasibility of the application of austempered ductile iron in the industrial sector with the aspect of machinability as well as the application of the models based on artificial intelligence, was given. At the end of the presentation, the influence of the aforementioned cutting regimes on cutting force components is presented as well.
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Affiliation(s)
- Borislav Savkovic
- Faculty of Technical Sciences, University of Novi Sad, 21000 Novi Sad, Serbia.
| | - Pavel Kovac
- Faculty of Technical Sciences, University of Novi Sad, 21000 Novi Sad, Serbia.
| | - Branislav Dudic
- Faculty of Management, Comenius University in Bratislava, 820 05 Bratislava, Slovakia.
- Faculty of Economics and Engineering Management, University Business Academy, 21000 Novi Sad, Serbia.
| | - Michal Gregus
- Faculty of Management, Comenius University in Bratislava, 820 05 Bratislava, Slovakia.
| | - Dragan Rodic
- Faculty of Technical Sciences, University of Novi Sad, 21000 Novi Sad, Serbia.
| | - Branko Strbac
- Faculty of Technical Sciences, University of Novi Sad, 21000 Novi Sad, Serbia.
| | - Nedeljko Ducic
- Faculty of Technical Sciences Cacak, University of Kragujevac, 32102 Cacak, Serbia.
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Bian R, Ding W, Liu S, He N. Research on High Performance Milling of Engineering Ceramics from the Perspective of Cutting Variables Setting. MATERIALS 2019; 12:ma12010122. [PMID: 30609701 PMCID: PMC6337323 DOI: 10.3390/ma12010122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 12/25/2018] [Accepted: 12/26/2018] [Indexed: 12/04/2022]
Abstract
The setting of cutting variables for precision milling of ceramics is important to both the machined surface quality and material removal rate (MRR). This work specifically aims at the performance of corner radius PCD (polycrystalline diamond) end mill in precision milling of zirconia ceramics with relatively big cutting parameters. The characteristics of the cutting zone in precision milling ceramics with corner radius end mill are analyzed. The relationships between the maximum uncut chip thickness (hmax) and the milling parameters including feed per tooth (fz), axial depth of cut (ap) and tool corner radius (rε) are discussed. Precision milling experiments with exploratory milling parameters that cause uncut chip thickness larger than the critical value were carried out. The material removal mechanism was also analyzed. According to the results, it is advisable to increase fz appropriately during precision milling ZrO2 ceramics with corner radius end mill. There is still a chance to obtain ductile processed surface, as long as the brittle failure area is controlled within a certain range. The appropriate increasing of ap, not only can prevent the brittle damage from affecting the machined surface, but also could increase the MRR. The milling force increases with increasing MRR, but the surface roughness can still be stabilized within a certain range.
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Affiliation(s)
- Rong Bian
- Industrial Center, Nanjing Institute of Technology; Nanjing 211167, China.
- Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology, Nanjing University of Aeronautics & Astronautics; Nanjing 210016, China.
| | - Wenzheng Ding
- Industrial Center, Nanjing Institute of Technology; Nanjing 211167, China.
| | - Shuqing Liu
- Industrial Center, Nanjing Institute of Technology; Nanjing 211167, China.
| | - Ning He
- Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology, Nanjing University of Aeronautics & Astronautics; Nanjing 210016, China.
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Editorial for the Special Issue on Micro-Machining: Challenges and Opportunities. MICROMACHINES 2018; 9:mi9110564. [PMID: 30715063 PMCID: PMC6266901 DOI: 10.3390/mi9110564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 10/30/2018] [Indexed: 11/24/2022]
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