A Comparative Study of Energy and Material Flow in Modulation-Assisted Machining and Conventional Machining

2014 ◽  
Author(s):  
Ho Yeung ◽  
Yang Guo ◽  
James B. Mann ◽  
W. Dale Compton ◽  
Srinivasan Chandrasekar
Keyword(s):  
Chip Formation ◽  
Material Flow ◽  
High Speed ◽  
Unique Feature ◽  
Low Frequency ◽  
Ductile Metals ◽  
Simultaneous Measurements ◽  
Formation Zone ◽  
Conventional Machining

A study has been made of deformation, forces and energy in modulation-assisted machining (MAM), wherein chip formation occurs in the presence of a controlled, low-frequency modulation superimposed on to the machining. A unique feature of the study is the use of high speed in situ imaging and image analysis to map material flow in the chip formation zone at high resolution; and simultaneous measurements of tool motions and forces, such that the instantaneous forces can be overlaid onto the chip formation process. The measurements show that the observed significant reductions in specific energy in MAM relative to conventional machining, when cutting ductile metals such as copper and Al 6061T6, are a consequence of chip formation with reduced strain levels in MAM. Additional insights into the chip formation are obtained by examining the effects of a chip aspect ratio parameter.

Effect of Low-Frequency Modulation on Deformation and Material Flow in Cutting of Metals

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Ho Yeung ◽  
Yang Guo ◽  
James B. Mann ◽  
W. Dale Compton ◽  
Srinivasan Chandrasekar
Keyword(s):  
Frequency Modulation ◽  
Chip Formation ◽  
Material Flow ◽  
High Speed ◽  
Surface Deformation ◽  
Low Frequency ◽  
High Speed Imaging ◽  
Machining Processes ◽  
Asperity Contacts ◽  
2D System

The deformation field, material flow, and mechanics of chip separation in cutting of metals with superimposed low-frequency modulation (<1000 Hz) are characterized at the mesoscale using high-speed imaging and particle image velocimetry (PIV). The two-dimensional (2D) system studied involves a sharp-wedge sliding against the workpiece to remove material, also reminiscent of asperity contacts in sliding. A unique feature of the study is in situ mapping of material flow at high resolution using strain fields and streaklines and simultaneous measurements of tool motions and forces, such that instantaneous forces and kinematics can be overlaid onto the chip formation process. The significant reductions in specific energy obtained when cutting with modulation are shown to be a consequence of discrete chip formation with reduced strain levels. This strain reduction is established by direct measurements of deformation fields. The results have implications for enhancing sustainability of machining processes and understanding surface deformation and material removal in wear processes.

In situ strain measurement in the chip formation zone during orthogonal cutting

2010 ◽  
Vol 5 (1) ◽  
pp. 1-8 ◽  
Author(s):  
E. Uhlmann ◽  
R. Gerstenberger ◽  
S. Herter ◽  
T. Hoghé ◽  
W. Reimers ◽  
...  
Keyword(s):  
Chip Formation ◽  
Strain Measurement ◽  
Orthogonal Cutting ◽  
Formation Zone ◽  
In Situ Strain Measurement

In Situ Analysis of Deformation Mechanics of Constrained Cutting Towards Enhanced Material Removal

2019 ◽  
Author(s):  
Yang Guo ◽  
Jisheng Chen ◽  
Amr Saleh
Keyword(s):  
Free Surface ◽  
Surface Finish ◽  
Simple Shear ◽  
Chip Formation ◽  
Material Removal ◽  
High Speed ◽  
Image Correlation ◽  
High Speed Imaging ◽  
Deformation Mechanics

Abstract Chip formation in conventional cutting occurs by deformation that is only partially bounded by the cutting tool. The unconstrained free surface is a complication in determining the deformation of chip formation. The constrained cutting employs a constraining tool in the cutting process to confine the otherwise free surface and enable direct control of the chip formation deformation. A study has been made on the deformation mechanics of plane-strain constrained cutting using high speed imaging and digital image correlation (DIC) methods. For different constrained levels (including unconstrained free cutting), material flow of chip formation is directly observed; strain rate and strain in the chip as well as the subsurface region are quantified; cutting forces are measured; and surface finish are examed. The study shows that chip formation in constrained cutting can occur in two different deformation modes, i.e., simple shear and complex extrusion, depending on the constrained level. Constrained cutting in simple shear regime can reduce strain, reduce cutting force and energy, and improve surface finish compared to free cutting, therefore it is more efficient for material removal than free cutting. Constrained cutting in the complex extrusion regime imposes a significant amount of surface / subsurface deformation and consumes a very high cutting energy, and therefore is not suitable for material removal. Furthermore, the mechanics of chip formation in both free cutting and constrained cutting, especially the roles played by the free surface and the constraining tool, are discussed.

Modulation-Assisted Machining: A New Paradigm in Material Removal Processes

2011 ◽  
Vol 223 ◽  
pp. 514-522 ◽  
Author(s):  
James B. Mann ◽  
Yang Guo ◽  
Christopher Saldana ◽  
Ho Yeung ◽  
W. Dale Compton ◽  
...  
Keyword(s):  
Tool Wear ◽  
Chip Formation ◽  
Material Removal ◽  
Surface Texturing ◽  
Low Frequency ◽  
Contact Condition ◽  
New Paradigm ◽  
Machining Performance ◽  
Removal Processes ◽  
Conventional Machining

Modulation Assisted Machining (MAM), based on controlled superimposition of low-frequency modulation to conventional machining, effects discrete chip formation and disrupts the severe contact condition at the tool-chip interface. The underlying theory of discrete chip formation and its implications are briefly described and illustrated. Benefits such as improved chip management and lubrication, reduction of tool wear, enhanced material removal, particulate manufacturing and surface texturing are highlighted using case studies. MAM represents a new paradigm for machining in that it deliberately employs ‘good vibrations’ to enhance machining performance and capability.

scholarly journals Organic monolayers disrupt plastic flow in metals

2020 ◽  
Vol 6 (51) ◽  
pp. eabc8900
Author(s):  
Tatsuya Sugihara ◽  
Anirudh Udupa ◽  
Koushik Viswanathan ◽  
Jason M. Davis ◽  
Srinivasan Chandrasekar
Keyword(s):  
Surface Energy ◽  
Self Assembly ◽  
High Speed ◽  
Flow Characteristic ◽  
Large Strain ◽  
Organic Monolayers ◽  
Ductile Metals ◽  
Adsorbed Films ◽  
Ductile To Brittle Transition

Adsorbed films often influence mechanical behavior of surfaces, leading to well-known mechanochemical phenomena such as liquid metal embrittlement and environment-assisted cracking. Here, we demonstrate a mechanochemical phenomenon wherein adsorbed long-chain organic monolayers disrupt large-strain plastic deformation in metals. Using high-speed in situ imaging and post facto analysis, we show that the monolayers induce a ductile-to-brittle transition. Sinuous flow, characteristic of ductile metals, gives way to quasi-periodic fracture, typical of brittle materials, with 85% reduction in deformation forces. By independently varying surface energy and molecule chain length via molecular self-assembly, we argue that this “embrittlement” is driven by adsorbate-induced surface stress, as against surface energy reduction. Our observations, backed by modeling and molecular simulations, could provide a basis for explaining diverse mechanochemical phenomena in solids. The results also have implications for manufacturing processes such as machining and comminution, and wear.

An atomic-resolution microscope study of Al contracts on GaAs

1986 ◽  
Vol 44 ◽  
pp. 726-727
Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn
Keyword(s):  
High Speed ◽  
Schottky Contacts ◽  
Detailed Knowledge ◽  
The Past ◽  
Semiconductor Interfaces ◽  
Deposited Metal ◽  
Microwave Applications ◽  
Free Interfaces ◽  
Potential Use

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions

Sign in / Sign up

Export Citation Format

Share Document