High Rake Angle Orthogonal Machining of Highly Ordered Pyrolytic Graphite Parallel to the Basal Plane

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
B. Jayasena ◽  
S. Subbiah ◽  
C. D. Reddy
Keyword(s):  
Basal Plane ◽  
Pyrolytic Graphite ◽  
Rake Angle ◽  
Machining Process ◽  
Dynamic Simulations ◽  
Kink Bands ◽  
Orthogonal Machining ◽  
Highly Ordered Pyrolytic Graphite ◽  
Graphite Sheets

High rake angle orthogonal machining of highly ordered pyrolytic graphite (HOPG) parallel to the basal plane was carried out to synthesize few layers of graphene. The quality of the graphite sheets was found to be an alliance of any pre-existing defects in the HOPG and the nature of the machining process itself. Presence of pre-existing defects such as kinks and discontinuous layers were observed during the lateral examination of HOPG structure prior to machining. Evidence of flat, folded, and rolled structures were found in exfoliated graphite sheets in addition to defects such as two types of kink bands. Multiple spikes in measured cutting forces were seen during machining due to disturbances in tool movement. Molecular dynamic simulations were carried out to support the argument that specific pre-existing defects such as discontinuous layers cause the marked disturbances during machining.

Electrochemically controlled winding and unwinding of substrate-supported carbon nanoscrolls

2018 ◽  
Vol 20 (8) ◽  
pp. 5900-5908 ◽  
Author(s):  
H. Tarábková ◽  
Z. Zelinger ◽  
P. Janda
Keyword(s):  
Electrolyte Solution ◽  
Basal Plane ◽  
Aqueous Electrolyte ◽  
Pyrolytic Graphite ◽  
Aqueous Electrolyte Solution ◽  
Highly Ordered Pyrolytic Graphite ◽  
Carbon Nanoscrolls

Carbon nanoscrolls (CNSs) formed spontaneously on the basal plane of highly ordered pyrolytic graphite (HOPG) show winding and unwinding movements when potential steps from 0 V to −0.5 V, −0.6 V and −0.9 V are applied on HOPG immersed in an aqueous electrolyte solution (0.1 M H2SO4).

Comparison Orthogonal Tube Turning Data Versus Finite Element Simulation Using LS Dyna

2013 ◽  
Author(s):  
Vishnu Vardhan Chandrasekaran ◽  
Lewis N. Payton
Keyword(s):  
Finite Element ◽  
Metal Cutting ◽  
Tool Material ◽  
Element Model ◽  
Rake Angle ◽  
Machining Process ◽  
Work Piece ◽  
Orthogonal Machining ◽  
Work Material ◽  
Cut Depth

The current study focuses on building a 2-Dimensional finite element model to simulate the orthogonal machining process under a dry machining environment in a commercially available FEA solver LS DYNA. One of the key objectives of this thesis is to carefully document the use of LS Dyna to model metal cutting, allowing other researchers to more quickly build on this work. Actual force data is obtained using an Orthogonal Tube Turning apparatus that has been statistically validated to an accuracy of 99+%. The work material used in this study is Aluminum 6061-T6 alloy. The tool material is tool steel, which is modeled as a rigid body. A Plastic Kinematic Material Hardening model is used to define the work material. Chip formation is based on the effective failure plastic strain. A constant coefficient of friction between the tool and work piece is used, obtained from the actual experimental results. The simulation is carried out with the same constant velocity, different rake angles and depth cuts as in the real world experiment. The cutting force and thrust force values obtained for each combination of rake angle and cut depth are validated against the experimental data obtained at Auburn University. The resulting model is considered valid enough to use for sensitivity analysis of the metal cutting process in aluminum alloy 6061-T6 in the university environment. The model is available publicly to any university from a website provided.

Nanobubble-assisted formation of carbon nanostructures on basal plane highly ordered pyrolytic graphite exposed to aqueous media

2010 ◽  
Vol 21 (9) ◽  
pp. 095707 ◽  
Author(s):  
Pavel Janda ◽  
Otakar Frank ◽  
Zdeněk Bastl ◽  
Mariana Klementová ◽  
Hana Tarábková ◽  
...  
Keyword(s):  
Basal Plane ◽  
Carbon Nanostructures ◽  
Pyrolytic Graphite ◽  
Aqueous Media ◽  
Highly Ordered Pyrolytic Graphite

On the non-uniqueness of the machining process

1978 ◽  
Vol 360 (1703) ◽  
pp. 587-610 ◽  
Keyword(s):  
Shear Stress ◽  
Slip Line ◽  
Interfacial Shear Stress ◽  
Rake Angle ◽  
Interfacial Shear ◽  
The Other ◽  
Machining Process ◽  
Line Field ◽  
Slip Line Field ◽  
Orthogonal Machining

The elimination of a class of possible slip-line field solutions for orthogonal machining indicates that the process is not uniquely defined. The range of possible solutions for any value of tool rake angle and interfacial shear stress is shown to be associated with large variations in the curvature of the machined chip. Machining conditions are split into two types, for one of which the machined chip will always curl, while the other has the Lee & Shaffer slip-line field as a lower limit of the solution range. The extent of the solution range for any value of friction is found to decrease with increasing rake angle. The analysis is shown to be consistent with certain experimental work available.

scholarly journals Understanding the electrochemistry of “water-in-salt” electrolytes: basal plane highly ordered pyrolytic graphite as a model system

2020 ◽  
Vol 11 (27) ◽  
pp. 6978-6989 ◽  
Author(s):  
Pawin Iamprasertkun ◽  
Andinet Ejigu ◽  
Robert A. W. Dryfe
Keyword(s):  
Basal Plane ◽  
Pyrolytic Graphite ◽  
Model System ◽  
Concentrated Solutions ◽  
Highly Ordered Pyrolytic Graphite ◽  
System P ◽  
The Stability ◽  
Stability Of Water

The stability of water-in-salt electrolyte systems is investigated using highly concentrated solutions of KF(aq) with graphite as a model system.

scholarly journals Capacitance of Basal Plane and Edge-Oriented Highly Ordered Pyrolytic Graphite: Specific Ion Effects

2019 ◽  
Vol 10 (3) ◽  
pp. 617-623 ◽  
Author(s):  
Pawin Iamprasertkun ◽  
Wisit Hirunpinyopas ◽  
Ashok Keerthi ◽  
Bin Wang ◽  
Boya Radha ◽  
...  
Keyword(s):  
Basal Plane ◽  
Pyrolytic Graphite ◽  
Highly Ordered Pyrolytic Graphite ◽  
Specific Ion Effects ◽  
Ion Effects

Polymer Stamp-Based Mechanical Exfoliation of Thin High-Quality Pyrolytic Graphite Sheets

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
David Hahn ◽  
Buddhika Jayasena ◽  
Zhigang Jiang ◽  
Shreyes N. Melkote
Keyword(s):  
High Frequency ◽  
Pyrolytic Graphite ◽  
Plane Shear ◽  
Pdms Stamp ◽  
Mechanical Exfoliation ◽  
Morphological Variations ◽  
Surface Areas ◽  
Highly Ordered Pyrolytic Graphite ◽  
Thermally Conductive ◽  
Graphite Sheets

This paper reports on a polymer stamp-based mechanical exfoliation method for producing thin (<1 μm) graphite sheets from a highly ordered pyrolytic graphite (HOPG) source by tailoring key exfoliation process parameters, utilizing in-plane shear oscillation during exfoliation, and controlling the thickness of a polydimethylsiloxane (PDMS) stamp. Experiments on the effect of high frequency in-plane shear oscillation and the effect of PDMS stamp thickness are designed to reduce the thickness of exfoliated layers and to minimize surface morphological variations. Results show that the exfoliated sheets consist of a range of layer thicknesses, surface areas, and surface morphological features. The exfoliated HOPG sheets are also found to be thinner, more electrically and thermally conductive, and of higher quality than commercially available pyrolytic graphite sheets.

Chatter Suppression via an Oscillating Cutter

1999 ◽  
Vol 121 (1) ◽  
pp. 54-60 ◽  
Author(s):  
F. Yang ◽  
B. Zhang ◽  
J. Yu
Keyword(s):  
Experimental Studies ◽  
Rake Angle ◽  
Transmission Mechanism ◽  
Machining Process ◽  
Chatter Suppression ◽  
Critical Issues ◽  
The Stability ◽  
Cutting System ◽  
Theoretical Analyses

Chatter is one of the critical issues in a machining process since it deteriorates the surface quality of a workpiece and reduces machining efficiency. A new method is developed to suppress chatter in which an oscillating cutter is used to machine the workpiece through a stepping motor and a transmission mechanism so as to vary tool rake angle continuously and periodically in process. Theoretical analyses are performed on the stability of the cutting system, and verified by the experimental studies. Both theoretical analyses and experimental results indicate that the method can suppress chatter in a turning process effectively. With the application of an oscillating cutter, the amplitude can be reduced by 80 percent in cutting a steel workpiece.

Deformation Replication

1970 ◽  
Vol 28 ◽  
pp. 280-281
Author(s):  
J. Temple Black
Keyword(s):  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Rake Face ◽  
Orthogonal Machining ◽  
Aluminum Chips ◽  
Before And After ◽  
Materials Used ◽  
Glass Knife ◽  
Very High

Tool materials used in ultramicrotomy are glass, developed by Latta and Hartmann (1) and diamond, introduced by Fernandez-Moran (2). While diamonds produce more good sections per knife edge than glass, they are expensive; require careful mounting and handling; and are time consuming to clean before and after usage, purchase from vendors (3-6 months waiting time), and regrind. Glass offers an easily accessible, inexpensive material ($0.04 per knife) with very high compressive strength (3) that can be employed in microtomy of metals (4) as well as biological materials. When the orthogonal machining process is being studied, glass offers additional advantages. Sections of metal or plastic can be dried down on the rake face, coated with Au-Pd, and examined directly in the SEM with no additional handling (5). Figure 1 shows aluminum chips microtomed with a 75° glass knife at a cutting speed of 1 mm/sec with a depth of cut of 1000 Å lying on the rake face of the knife.

scholarly journals Serrated Chips Formation in Micro Orthogonal Cutting of Ti6Al4V Alloys with Equiaxial and Martensitic Microstructures

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 197 ◽  
Author(s):  
ZeJia Zhao ◽  
Suet To ◽  
ZhuoXuan Zhuang
Keyword(s):  
Cutting Force ◽  
Unit Length ◽  
Orthogonal Cutting ◽  
Machining Process ◽  
Orthogonal Machining ◽  
Large Yield ◽  
Power Spectral ◽  
Straight Line ◽  
Serrated Chips ◽  
Electropulsing Treatment

The formation of serrated chips is an important feature during machining of difficult-to-cut materials, such as titanium alloy, nickel based alloy, and some steels. In this study, Ti6Al4V alloys with equiaxial and acicular martensitic microstructures were adopted to analyze the effects of material structures on the formation of serrated chips in straight line micro orthogonal machining. The martensitic alloy was obtained using highly efficient electropulsing treatment (EPT) followed by water quenching. The results showed that serrated chips could be formed on both Ti6Al4V alloys, however the chip features varied with material microstructures. The number of chip segments per unit length of the alloy with martensite was more than that of the equiaxial alloy due to poor ductility. Besides, the average cutting and thrust forces were about 8.41 and 4.53 N, respectively, for the equiaxed Ti6Al4V alloys, which were consistently lower than those with a martensitic structure. The high cutting force of martensitic alloy is because of the large yield stress required to overcome plastic deformation, and this force is also significantly affected by the orientations of the martensite. Power spectral density (PSD) analyses indicated that the characteristic frequency of cutting force variation of the equiaxed alloy ranged from 100 to 200 Hz, while it ranged from 200 to 400 Hz for workpieces with martensites, which was supposedly due to the formation of serrated chips during the machining process.

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