Experimental Study of the Impact of a Vibrating Wire on Free Abrasive Machining as Correlated to the Modeling of Vibration Subject to an Oscillating Boundary Condition

2020 ◽  
Vol 143 (5) ◽  
Author(s):  
Liming Li ◽  
Imin Kao
Keyword(s):  
Boundary Condition ◽  
Material Removal ◽  
Substrate Surface ◽  
Abrasive Machining ◽  
Vibrating Wire ◽  
Fracture Formation ◽  
Oscillating Boundary ◽  
The Impact ◽  
Brittle Material Removal ◽  
Free Abrasive

Abstract In this paper, we study experimentally the impact of a vibrating wire on the free abrasive machining (FAM) process in removing material from the surface of brittle materials, such as silicon. An experimental setup was designed to study the FAM process on silicon substrate surface by using a slurry-fed wire with a periodic excitation. An analytical solution of a wire moving axially, subject to an oscillating boundary condition with damping from abrasive slurry, was derived based on the partial differential equation of motion. Experiments were conducted on the apparatus using a wire with an oscillating boundary. It was found that the amplitudes of vibration were larger at the side of the oscillatory boundary, which caused more FAM interaction near the edge of the oscillatory boundary with larger material removal that was measured and validated. Furthermore, experiments were conducted to elucidate the effectiveness of brittle material removal using FAM with abrasive grits: (i) under dry condition, (ii) with water, and (iii) with abrasive slurry. Experimental results showed that the vibration of wire resulted in plastic deformation on the surface of silicon wafer. The abrasive grits in slurry driven by a vibrating wire generated material removal through observable grooves and fractures on the surface of silicon due to FAM in just a few minutes. The grooves from FAM process is an outcome of brittle machining through fracture formation and concatenation, generated by the indentation of abrasive grits on the silicon surface.

Modeling and Experimental Study of the Impact on Free Abrasive Machining (FAM) due to Vibration of a Thin Wire Subject to an Oscillating Boundary Condition

2019 ◽  
Author(s):  
Liming Li ◽  
Imin Kao
Keyword(s):  
Boundary Condition ◽  
Experimental Study ◽  
Moving Boundary ◽  
Damping Factor ◽  
Periodic Excitation ◽  
Abrasive Machining ◽  
Vibrating Wire ◽  
Oscillating Boundary ◽  
The Impact ◽  
Free Abrasive

Abstract This paper investigates the impact on free abrasive machining (FAM) process using a vibrating wire with an oscillating boundary condition. The experimental results show that the vibration of wire in slurry with abrasive grits can result in material removal due to FAM on brittle material. We present a theoretical model of a wire moving axially at a constant speed, subject to an oscillating boundary condition with damping, and derive an analytical solution of the partial differential equation of motion. Based on the modeling and analysis, the frequency of vibration of wire corresponds to the frequency at the oscillating boundary at steady state. The damping factor suppresses the lateral movement of wire from the fixed boundary to moving boundary when it is increased. The change of axial wire speed or the oscillating frequency at boundary can counteract the suppression on the vibration response induced by increased damping factor. This study also presents an experimental study using an experimental setup of a slurry-fed wire with a periodic excitation to study the FAM process on silicon. The results of experiments show that vibration of wire can impart the silicon carbide abrasive grits in slurry to generate observable grooves and fractures on the surface of silicon in just a few minutes. The grooves and fractures are generated by the indentation of abrasive grits via loading and unloading on the silicon surface. When the vibrating wire is only fed with water without abrasives or under a dry condition, compressive deformation with shallow grooves on silicon is observed; however, the surface is found to be free of surface features of indentation and scratching. Furthermore, evidence of both wire compression and abrasive machining is more pronounced at the edges of silicon specimen, especially at the edge close to the periodic excitation, which is consistent to our modeling.

scholarly journals Surface Analysis of Metal Materials After Water Jet Abrasive Machining

2015 ◽  
Vol 63 (5) ◽  
pp. 1529-1533
Author(s):  
Pavel Polák ◽  
Ján Žitňanský ◽  
Petr Dostál ◽  
Katarína Kollárová
Keyword(s):  
Surface Roughness ◽  
Production Technology ◽  
Material Removal ◽  
Water Jet ◽  
Machining Parameters ◽  
Metallic Materials ◽  
Abrasive Machining ◽  
Water Jet Cutting ◽  
Metal Materials ◽  
The Impact

In this article, we deal with a progressive production technology using the water jet cutting technology with the addition of abrasives for material removal. This technology is widely used in cutting various shapes, but also for the technology of machining such as turning, milling, drilling and cutting of threads. The aim of this article was to analyse the surface of selected types of metallic materials after abrasive machining, i.e. by assessing the impact of selected machining parameters on the surface roughness of metallic materials.

A Study on Evolution of Splat Radius and Temperature in Thermal Spray Process

2018 ◽  
Author(s):  
Manpreet Dash ◽  
Sangharsh Kumar ◽  
Partha Pratim Bandyopadhyay ◽  
Anandaroop Bhattacharya
Keyword(s):  
Heat Transfer ◽  
Thermal Spray ◽  
Molten Metal ◽  
Spray Deposition ◽  
Substrate Surface ◽  
Metal Droplet ◽  
Droplet Impingement ◽  
Impact Process ◽  
The Impact ◽  
Maximum Spreading

The impact process of a molten metal droplet impinging on a solid substrate surface is encountered in several technological applications such as ink-jet printing, spray cooling, coating processes, spray deposition of metal alloys, thermal spray coatings, manufacturing processes and fabrication and in industrial applications concerning thermal spray processes. Deposition of a molten material or metal in form of a droplet on a substrate surface by propelling it towards it forms the core of the spraying process. During the impact process, the molten metal droplet spreads radially and simultaneously starts losing heat due to heat transfer to the substrate surface. The associated heat transfer influences impingement behavior. The physics of droplet impingement is not only related to the fluid dynamics, but also to the respective interfacial properties of solid and liquid. For most applications, maximum spreading diameter of the splat is considered to be an important factor for droplet impingement on solid surfaces. In the present study, we have developed a model for droplet impingement based on energy conservation principle to predict the maximum spreading radius and the radius as a function of time. Further, we have used the radius as a function of time in the heat transfer equations and to study the evolution of splat-temperature and predict the spreading factor and the spreading time and mathematically correlate them to the spraying parameters and material properties.

scholarly journals Simulation of the ductile machining mode of silicon

2021 ◽  
Author(s):  
Hagen Klippel ◽  
Stefan Süssmaier ◽  
Matthias Röthlin ◽  
Mohamadreza Afrasiabi ◽  
Uygar Pala ◽  
...  
Keyword(s):  
Brittle Material ◽  
Material Removal ◽  
Machining Process ◽  
Ductile Material ◽  
Diamond Wire ◽  
Ductile Machining ◽  
Mesh Free ◽  
Diamond Wire Sawing ◽  
Material Removal Mode ◽  
Brittle Material Removal

AbstractDiamond wire sawing has been developed to reduce the cutting loss when cutting silicon wafers from ingots. The surface of silicon solar cells must be flawless in order to achieve the highest possible efficiency. However, the surface is damaged during sawing. The extent of the damage depends primarily on the material removal mode. Under certain conditions, the generally brittle material can be machined in ductile mode, whereby considerably fewer cracks occur in the surface than with brittle material removal. In the presented paper, a numerical model is developed in order to support the optimisation of the machining process regarding the transition between ductile and brittle material removal. The simulations are performed with an GPU-accelerated in-house developed code using mesh-free methods which easily handle large deformations while classic methods like FEM would require intensive remeshing. The Johnson-Cook flow stress model is implemented and used to evaluate the applicability of a model for ductile material behaviour in the transition zone between ductile and brittle removal mode. The simulation results are compared with results obtained from single grain scratch experiments using a real, non-idealised grain geometry as present in the diamond wire sawing process.

scholarly journals Templated quasicrystalline ordering of single elements and molecules

2014 ◽  
Vol 70 (a1) ◽  
pp. C81-C81
Author(s):  
H. R. Sharma ◽  
J. A. Smerdon ◽  
K. Nozawa ◽  
K. M. Young ◽  
T. P. Yadav ◽  
...  
Keyword(s):  
Substrate Surface ◽  
Chemical Properties ◽  
Scanning Tunneling ◽  
Three Dimension ◽  
Tunneling Microscopy ◽  
Quantum Size ◽  
Adsorption Energies ◽  
Molecular Layers ◽  
Physical And Chemical ◽  
The Impact

We have used quasicrystals as templates for the exploration of new epitaxial phenomena. Several interesting results have been observed in the growth on surfaces of the common Al-based quasicrystals [1]. These include pseudomorphic monolayers, quasiperiodically modulated multilayer structures, and fivefold-twinned islands with magic heights influenced by quantum size effects [1]. Here we present our recent works on the growth of various elements and molecules on a new substrate, icosahedral (i) Ag-In-Yb quasicrystal, which have resulted in various epitaxial phenomena not observed previously. The growth of Pb on the five-fold surface of i-Ag-In-Yb yields a film which possesses quasicrystalline ordering in three-dimension [2]. Using scanning tunneling microscopy (STM) and DFT calculations of adsorption energies, we find that lead atoms occupy the positions of atoms in the rhombic triacontahedral (RTH) cluster, the building block of the substrate, and thus grow in layers with different heights and adsorption energies. The adlayer–adlayer interaction is crucial for stabilizing the epitaxial quasicrystalline structure. We will also present the first example of quasicrystalline molecular layers. Pentacene adsorbs at tenfold-symmetric sites of Yb atoms around surface-bisected RTH clusters, yielding quasicrystalline order [3]. Similarly, C-60 growth on the five-fold surface of i-Al-Cu-Fe at elevated temperature produces quasicrystalline layer, where the growth is mediated by Fe atoms on the substrate surface [3]. The finding of quasicrystalline thin films of single elements and molecules opens an avenue for further investigation of the impact of the aperiodic atomic order over periodic order on the physical and chemical properties of materials.

Analysis for the Effect of Inverter Ripple Current on Fuel Cell Operating Condition

2001 ◽  
Author(s):  
Randall S. Gemmen
Keyword(s):  
Boundary Condition ◽  
Fuel Cell ◽  
Mass Transport ◽  
Transient Behavior ◽  
Mechanical State ◽  
Dimensional Model ◽  
One Dimensional ◽  
Fuel Cell Stack ◽  
A Cell ◽  
The Impact

Abstract The effect of inverter ripple current on fuel cell stack performance and stack lifetime remains uncertain. This paper provides a first attempt to examine the impact of inverter load dynamics on the fuel cell. Since reactant utilization is known to impact the mechanical state of a fuel cell, it is suggested that the varying reactant conditions surrounding the cell govern, at least in part, the lifetime of the cells. This paper investigates these conditions through the use of a dynamic model for the bulk conditions within the stack, as well as a one-dimensional model for the detailed mass transport occurring within the electrode of a cell. These two independent modeling approaches help to verify their respective numerical procedures. In this work, the inverter load is imposed as a boundary condition to the models. Results show the transient behavior of the reactant concentrations within the stack, and of the mass diffusion within the electrode under inverter loads with frequencies between 30 Hz and 1250 Hz.

Non-Contact Ultrasonic Abrasive Machining of Wire-Electrical Discharge Machined SUS304 Steel

2017 ◽  
Author(s):  
K. L. Tan ◽  
S. H. Yeo
Keyword(s):  
Material Removal ◽  
Cavitation Erosion ◽  
Removal Rate ◽  
Recast Layer ◽  
Ultrasonic Machining ◽  
Abrasive Machining ◽  
Efficient Removal ◽  
Abrasive Particles ◽  
The Poor ◽  
Lower Material

Non-contact ultrasonic abrasive machining (NUAM) is a variant of ultrasonic machining (USM). In NUAM, material is removed predominantly by cavitation erosion in abrasive slurry. Due to a significantly lower material removal rate than traditional USM, NUAM is investigated for its applicability on surface modification and finishing in this study. Experiments were conducted on SUS304 steel samples machined by wire electrical discharged machining (WEDM). Due to the thermal spark phenomenon during WEDM, a thermal recast layer, of thickness approximately 15 μm, is often left over on the specimen’s surface after the process. The undesired thermal recast layer contributes to the poor surface integrity of specimens. A NUAM system was configured using a 40 kHz ultrasonic system. Ultrasonic vibration amplitude of 70 μm at the horn tip was used to generate cavitation bubbles in the abrasive slurry. NUAM was found to be effective in removing the unstable thermal recast layers by means of cavitation erosion. As a result, the average surface roughness, Ra, of the specimens improved from approximately 2.5 μm to ∼1.7 μm after 20 minutes of processing time. Furthermore, the addition of abrasive particles was observed to aid in more efficient removal of thermal recast layers than a pure cavitation condition.

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