Bio: K.S. Neo is an academic researcher from National University of Singapore. The author has contributed to research in topics: Machining & Diamond tool. The author has an hindex of 17, co-authored 20 publications receiving 1040 citations.
TL;DR: In this article, finite element analysis (FEA) of micromachining using the arbitrary Lagrangian-Eulerian (ALE) method showed that chip is formed through material extrusion under a critical a/r
TL;DR: In this paper, the machinability of sintered tungsten carbide (WC) was investigated by applying the ultrasonic elliptical vibration cutting (UEVC) technique.
Abstract: Sintered tungsten carbide (WC) is an extremely hard and brittle material extensively used in tool manufacturing industries. However, the current cutting technologies for shaping this typical hard-to-machine material are still cost ineffective. In this study, polycrystalline diamond (PCD) tools are used to study the machinability of sintered WC (~15% Co) by applying the ultrasonic elliptical vibration cutting (UEVC) technique. Firstly, it presents the UEVC principle and the effects of speed ratio (i.e. the ratio of the nominal cutting speed to the maximum tool vibration speed in the cutting direction) on the tool–workpiece relative motion as the cutting speed greatly influences the UEVC performance. Then UEVC experiments are carried out to analyze the cutting force, tool-wear progression, chip formation and surface quality against the cutting time at different speed ratios. The results show that when the speed ratio decreases, the resultant cutting force and the tool flank wear decrease while the surface finish improves. Average surface roughness, Ra, in a range between 0.030 and 0.050 μm is achieved at speed ratios less than 0.107. The experimental findings suggest that the commercial PCD tools can be used to machine sintered WC to achieve ultraprecision surface by applying the UEVC technique, which will be cost effective for miniature cutting technologies in future.
TL;DR: In this paper, the effects of tool edge radius on the frictional contact and flow stagnation phenomenon, the stick-slide behavior and contact stress distributions, the evolutions of contact length, and the relationship between material deformation and total contact length were investigated.
Abstract: The contact phenomenon during micromachining is complicated due to the tool edge radius. This paper presents investigation of the effects of tool edge radius on the frictional contact and flow stagnation phenomenon, the stick–slide behavior and contact stress distributions, the evolutions of contact length, and the relationship between material deformation and total contact length. Through the arbitrary Lagrangian–Eulerian FE modeling approach, our findings revealed that the flow stagnation during material separations could be attributed to the counterbalance of shear contact components and it appeared to be insensitive to machining magnitude where a constant stagnation point angle of 58.5±0.5° was determined for a wide range of undeformed chip thicknesses. Three distinctive sticking and sliding regions associated with the flow stagnation phenomenon on the cutting tool were discovered following the identification of two stress criteria for sticking, τf=0 and/or τf=kf. In addition, the influence of tool edge radius on contact length and material deformation was determined and a theoretical model for the contact length of tool-based micromachining was proposed. It was also observed that tool–chip contact evolved in two successive stages through a series of intermittent sticking and sliding interactions as governed by the undeformed chip thickness and the transition of effective rake angle. An ultraprecision machining setup coupled with a high-speed and small field-of-view photography technique was proposed for experimental substantiation of the numerical results.
TL;DR: In this article, the authors investigated tool life and cutting force based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques and showed that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to better lubrication and cooling effect.
Abstract: Titanium machining poses a great challenge to cutting tools due to its severe negative influence on tool life primarily due to high temperature generated and strong adhesion in the cutting area. Thus, various coolant supply methods are widely used to improve the machining process. On account of this, tool life and cutting force are investigated based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques. The experimental results show that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to the better lubrication and cooling effect.
TL;DR: In this article, the tool-based micromachining technology for nanosurface generation on silicon wafers has been discussed, and it is hoped that this process will be able to replace the current technique, chemical mechanical polishing (CMP) process.
TL;DR: Molecular dynamics simulations have been used to understand the occurrence of brittle-ductile transition due to the high-pressure phase transformation (HPPT), which induces Herzfeld-Mott transition.
Abstract: Molecular dynamics (MD) simulation has enhanced our understanding about ductile-regime machining of brittle materials such as silicon and germanium. In particular, MD simulation has helped understand the occurrence of brittle–ductile transition due to the high-pressure phase transformation (HPPT), which induces Herzfeld–Mott transition. In this paper, relevant MD simulation studies in conjunction with experimental studies are reviewed with a focus on (i) the importance of machining variables: undeformed chip thickness, feed rate, depth of cut, geometry of the cutting tool in influencing the state of the deviatoric stresses to cause HPPT in silicon, (ii) the influence of material properties: role of fracture toughness and hardness, crystal structure and anisotropy of the material, and (iii) phenomenological understanding of the wear of diamond cutting tools, which are all non-trivial for cost-effective manufacturing of silicon. The ongoing developmental work on potential energy functions is reviewed to identify opportunities for overcoming the current limitations of MD simulations. Potential research areas relating to how MD simulation might help improve existing manufacturing technologies are identified which may be of particular interest to early stage researchers.
TL;DR: A critical overview of UVAM is presented, covering different vibration-assisted machining styles, device architectures, and theoretical analysis, and based on the current limitations and challenges, device improvement and theoretical breakthrough play a significant role in future research on UVAM.
Abstract: Compared to conventional machining (CM), ultrasonic vibration-assisted machining (UVAM) with high-frequency and small-amplitude has exhibited good cutting performances for advanced materials. In recent years, advances in ultrasonic generator, ultrasonic transducer, and horn structures have led to the rapid progress in the development of UVAM. Following this trend, numerous new design requirements and theoretical concepts have been proposed and studied successively, however, very few studies have been conducted from a comprehensive perspective. To address this gap in the literature and understanding the development trend of UVAM, a critical overview of UVAM is presented in this study, covering different vibration-assisted machining styles, device architectures, and theoretical analysis. This overview covers the evolution of typical hardware systems used to achieve vibratory motions from the one-dimensional UVAM to three-dimensional UVAM, the discussion of cutting characteristics with periodic separation between the tools and workpiece and the analysis of processing properties. Challenges for UVAM include ultrasonic vibration systems with high power, large amplitude, and high efficiency, as well as theoretical research on the dynamics and cutting characteristics of UVAM. Consequently, based on the current limitations and challenges, device improvement and theoretical breakthrough play a significant role in future research on UVAM.
TL;DR: A review of cutting edge preparation technologies and methods for cutting edge characterization can be found in this article, where the authors discuss the influence of cutting-edge geometry on chip formation, material flow, as well as mechanical and thermal loads on the tool.
TL;DR: In this paper, a neural network approach is presented for the prediction and control of surface roughness in a computer numerically controlled (CNC) lathe, which is a type of back-propagation.
TL;DR: In this article, the performance of various type of polycrystalline cubic boron nitride (PCBN) cutting tools during machining of aluminium alloy reinforced by silicon carbide metal matrix composite (Al-SiC MMC) was investigated.