Prof. Ahn, Sung-Hoon (安成勳)

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Chapter 9. Material-Removal Processes: Abrasive, Chemical, Electrical, and High-Energy Beams

Prof. Ahn, Sung-Hoon ( 安成勳 )

School of Mechanical and Aerospace Engineering

Seoul National University

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Grinding ( 연삭 ) (1)

 Hardness

 Friability (

깨짐성

)



Self sharpening (자생작용)



Grain fragments rapidly

 Grain size (

입도

)



Grit number (입도지수)



10 > 100 > 500

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Prof. Ahn, Sung-Hoon

Grinding ( 연삭 ) (2)



Irregular geometry of grains.



Highly negative rake angle : -60

°

or even lower.



The radial positions of the grains in a grinding wheel vary.



High cutting speed : ~30m/s

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Residual stresses

(5)

Surface Grinding ( 평면연삭 )

(6)

Cylindrical Grinding ( 원통연삭 )

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Internal Grinding ( 내면연삭 )

(8)

Centerless Grinding ( 무심연삭 )

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Ultrasonic Machining ( 초음파가공 )

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Finishing Operations ( 마무리공정 )

 Honing ( 호닝 )

 Superfinishing

 Lapping ( 래핑 )

 Polishing ( 연마 ) / Buffing ( 버핑 )

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Lapping

(12)

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Chemical Machining ( 화학적가공 )

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Electrochemical Machining / Grinding

 ECM (

전해가공

)  ECG (

전해연삭

)

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Electro Discharge Machining (EDM)

 EDM ( 방전가공 )

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Micro ECM / EDM

Ref.: Prof. C. N. Chu

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Wire EDM

 Wire EDM ( 방전와이어 커팅 )

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Laser beam machining (LBM)

 Light Amplification by Stimulated Emission of Radiation (LASER)

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First Ruby Laser

1960, Theodore Maiman, USA

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Pulsed Laser

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Applications of Laser

Cutting Heat treating Welding

Applications W orkpiece

materials Laser ty pe

Cutting Metal PCO₂, CW CO₂, Nd:Y AG, ruby

Plastics CW CO₂

Ceramic PCO₂

Drilling Metal PCO2, CW CO2, Nd:glass, ruby

Plastics Ex cimer

Marking Metal PCO₂, Nd:Y AG

Plastics Ex cimer

Ceramic Ex cimer

Surface treatment Matal CW CO₂

W elding Matal PCO₂, CW CO₂, Nd:Y AG, Nd:glass, ruby

Table 9.5 General Applications of Laser in Manufacturing

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Laser Micro Drilling

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Micro LBM

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Electron Beam Machining

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Focused Ion Beam System (1)

 What is Focused Ion Beam ?



Nanoscale Hybrid Fabrication Tool

• Sputtering

• Deposition

 FIB Components



Ion Gun (10

^-7

torr)

• Liquid Metal Ion Source (LMIS)



Ion Optical Column

• Electrostatic Lens

• Variable Aperture



Vacuum Chamber (10

^-6

torr)



Specimen Stage

• Eucentric Stage



Gas Nozzle

• Carbon

• Platinum

• Tungsten Schematics of FIB System

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Focused Ion Beam System (2)

 Hybrid Fabrication Methods

Primary Ions Sputtered Particles (ions or neutrals)

Sputtering (Milling) Deposition

Precursor Molecules

Volatile Products

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Focused Ion Beam System (3)

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Case study: Stent

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CMP

Planarization using both chemical and mechanical process

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 Local planarization



Height control (resolution < 1 um)



Surface roughness (Ra < 20 nm)

 Micro Tool



Tungsten Carbide (WC ISO K30)

Nano grinding

Movie. Nano grinding process

X 8

Ag sample

Micro tool 40 μm dia.

20 μm 20 μm

IDIM, SNU

10 μm

Optical microscope High

resolution CCD camera

High speed 4-axis Nano-

stage

Multimeter Software and

User Interface

MCS Controller (Labview)

Sample

Tool z y

x

Before After

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Prof. Ahn, Sung-Hoon (소모마멸)

Nano grinding

Computer

Spindle Tool

Nano stage

CCD camera

Ohmmeter MCS

controller Work

piece

T-axis

X-axis Z-axis Y-axis

Micro scope

Contact detection and origin set

Height set from the substrate

Planarization progress

Microstructure of flat surface

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