Study on the Surface Damage Layer in Multiple Grinding of Quartz Glass by Molecular Dynamics Simulation

2017 ◽  
Vol 46 ◽  
pp. 192-202 ◽  
Author(s):  
Tao Liu ◽  
Xiao Guang Guo ◽  
Qiang Li ◽  
Ren Ke Kang ◽  
Dong Ming Guo
Keyword(s):  
Molecular Dynamics ◽  
Quartz Glass ◽  
Surface Damage ◽  
Dynamics Simulation ◽  
Machining Parameters ◽  
Machined Surface ◽  
Grinding Processes ◽  
Damage Layer ◽  
Ultra Precision

The paper focuses on the surface damage of quartz glass in multiple grinding, so as to find out the machining parameters that can improve the surface quality of quartz glass. Molecular dynamics (MD) method is adopted to machine the quartz glass. Firstly, the initial grinding is done on quartz glass with the depth of 12 Å. Based on the initial grinding, no feed grinding processes are done for three times separately and the feed grinding processes are carried out on the damage layer left by the previous process. By the coordination number (CN), machined surface topographies of quartz glass are gained and regions of densification are marked. Moreover, the damage layer thickness of different machined surface is also calculated. By analyzing the density of different surface damage layers, the regulation of the density distribution is obtained. Finally, the nanoindentation hardness is gained by different load-displacement curves in nanoindentation simulation. The results show that the first no feed grinding and the second feed grinding can improve the accuracy and quality of grinding. Too many no feed grinding processes and other feed grinding processes will induce serious damage of the machined surface, which is clearly showed in the obvious increase in the density, hardness and thickness of the damage layer. At last, the results of the density analysis and nanoindentation also proved that the densification and hardness of quartz glass cannot increase unlimited. The results can be applied in the ultra-precision grinding of quartz glass to control the thickness of damage layer and improve the quality of processing.

Fractal-Based Analysis of the Relation Between Surface Finish and Machine Vibration in Milling Operation

2019 ◽  
Vol 19 (01) ◽  
pp. 2050006 ◽  
Author(s):  
Muhammad Owais Qadri ◽  
Hamidreza Namazi
Keyword(s):  
Surface Quality ◽  
Complex Structure ◽  
Vibration Signal ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Machined Surface ◽  
Machine Vibration ◽  
Milling Operation ◽  
Surface Changes

Analysis of surface quality of machined workpiece is an important issue in machining of materials. For this purpose, scientists analyze how the texture of machined surface changes due to different conditions. Machine vibration is one of the factors that highly affects the surface quality of machined surface. In this research, we analyze the relation between machine vibration and surface quality of machined workpiece. For this purpose, we employ fractal theory and analyze how the complex structure of machined surface changes with the complex structure of machine vibration signal in case of variations of machining parameters, namely, depth of cut, feed rate and spindle speed, in milling operation. Based on the results, variations of surface quality of machined workpiece are related with the variations of complexity of machine vibration signal. The method of analysis employed in this research can be applied to other machining operations in order to find the relation between machine vibration and surface quality of machined workpiece.

scholarly journals Molecular Dynamics Simulation on the Influences of Nanostructure Shape, Interfacial Adhesion Energy, and Mold Insert Material on the Demolding Process of Micro-Injection Molding

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1573 ◽  
Author(s):  
Jin Yang ◽  
Can Weng ◽  
Jun Lai ◽  
Tao Ding ◽  
Hao Wang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Injection Molding ◽  
Interfacial Adhesion ◽  
Mold Insert ◽  
Adhesion Energy ◽  
Dynamics Simulation ◽  
Micro Injection Molding ◽  
Interfacial Adhesion Energy

In micro-injection molding, the interaction between the polymer and the mold insert has an important effect on demolding quality of nanostructure. An all-atom molecular dynamics simulation method was performed to study the effect of nanostructure shape, interfacial adhesion energy, and mold insert material on demolding quality of nanostructures. The deformation behaviors of nanostructures were analyzed by calculating the non-bonded interaction energies, the density distributions, the radii of gyration, the potential energies, and the snapshots of the demolding stage. The nanostructure shape had a direct impact on demolding quality. When the contact areas were the same, the nanostructure shape did not affect the non-bonded interaction energy at PP-Ni interface. During the demolding process, the radii of gyration of molecular chains were greatly increased, and the overall density was decreased significantly. After assuming that the mold insert surface was coated with an anti-stick coating, the surface burrs, the necking, and the stretching of nanostructures were significantly reduced after demolding. The deformation of nanostructures in the Ni and Cu mold inserts were more serious than that of the Al2O3 and Si mold inserts. In general, this study would provide theoretical guidance for the design of nanostructure shape and the selection of mold insert material.

Graphitization Wear of Diamond Tool in Nanometric Cutting of Single Crystal Silicon

2014 ◽  
Vol 609-610 ◽  
pp. 751-757 ◽  
Author(s):  
Jia Chun Wang ◽  
Ming Ming Xin ◽  
Si Yu Cao ◽  
Teng Zhao
Keyword(s):  
Diamond Tool ◽  
Single Crystal Silicon ◽  
Dynamics Modeling ◽  
Machined Surface ◽  
Crystal Silicon ◽  
Nanometric Cutting ◽  
Coordination Numbers ◽  
Molecular Dynamics Modeling ◽  
Ultra Precision

During ultra-precision cutting of brittle materials, the wear of diamond tool seriously affects the quality of machined surface. By molecular dynamics modeling of nanometric cutting, the generation of graphitization and its formation process at the cutting edge of tool are observed. By analyzing the process, the reason of the graphitization wear is mainly thermo-chemical reactions. By calculating the changes of coordination numbers of the tool atoms, graphitization conversion rate keeps increasing along the cutting process but gets stable after a certain length, which indicates the graphitization wear will occur in the same process.

Molecular Dynamics Simulation of a Cutting Method by Making Use of Localized Hydrostatic Pressure

2016 ◽  
Vol 1136 ◽  
pp. 156-161 ◽  
Author(s):  
Jun Shimizu ◽  
Keito Uezaki ◽  
Li Bo Zhou ◽  
Takeyuki Yamamoto ◽  
Teppei Onuki ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Hydrostatic Pressure ◽  
Cutting Tool ◽  
Dynamics Simulation ◽  
Burr Formation ◽  
Rectangular Hole ◽  
Machined Surface ◽  
Cutting Zone ◽  
Machined Surface Integrity

This study aims to develop a cutting method, which enables to generate a localized hydrostatic pressure field in the vicinity of cutting zone in order to improve the machined surface integrity without causing unnecessary plastic deformation. In the previous work, a molecular dynamics simulation was performed using a newly developed cutting tool equipped with a planer jig with a rectangular hole for the cutting chip elimination, and it was confirmed that the developed cutting tool has advantages in giving a relatively high-hydrostatic stress field in the vicinity of the cutting zone and in suppressing the burr formation. In this report, further molecular dynamics simulation was performed in order to clarify the influence of jig shape on the cutting phenomena and machined surface integrity. As a result, it is found that a cutting tool of which front and side except for the rectangular hole are covered by the planer jig is the most advantageous for supplying high hydrostatic pressure and suppressing burr formation.

Research on Subsurface Damage of Lapping Sapphire with Diamond Fixed Abrasive

2020 ◽  
Vol 866 ◽  
pp. 143-151
Author(s):  
Jian Bin Wang ◽  
Yong Qiang Tong ◽  
Ben Chi Jiang ◽  
Da Shu ◽  
Gang Wang
Keyword(s):  
Surface Quality ◽  
Surface Damage ◽  
Subsurface Damage ◽  
Indentation Fracture ◽  
Damage Layer ◽  
Damage Depth ◽  
The Difference ◽  
Fixed Abrasive ◽  
Free Abrasive

The depth of surface/subsurface damage layer is the key index of surface quality of sapphire. In this paper, that depth model of the surface/subsurface damage lay characterized by the crack length was established according to the mechanical theory of indentation fracture. The cutting relation between abrasive and workpiece and the difference of the depth of subsurface damage crack are analyzed. It is preliminarily estimated that the length of sub-surface damage crack of free abrasive sapphire is about 2.46 times that of fixed abrasive when considering only the contact hardness of abrasive grain under static load. Diamond abrasives with size of W20 were adopted to carry out experiments in free and fixed lapping methods. The results show that the surface/subsurface damage depth is 9.87μm and 3.63μm respectively. It is easier to obtain good sub-surface quality by using the fixed abrasive method than free abrasive at the same particle size.

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