Chapter 4. Surfaces, Tribology, Dimensions Inspection & … · 2018. 1. 30. · 4 4 6 . 3 0 5 A M A...

4 4 6 . 3 0 5 A M A N U F A C T U R I N G P R O C E S S E S

Chapter 4. Surfaces, Tribology, Dimensions Inspection & QualityDimensions, Inspection & Quality

Sung-Hoon AhnSchool of Mechanical and Aerospace Engineering

Seoul National UniversitySeoul National University

2

IntroductionSurface properties affect

F i ti dFriction and wearLubricationPainting coating welding soldering adhesive bonding corrosionPainting, coating, welding, soldering, adhesive bonding, corrosion resistanceCrack initiationThermal and electrical conductivity

Tribology FrictionWearLubricationLubrication

3

Surface structureOxide layer (hard, brittle, abrasive)

I F O F O F OIron: FeO, Fe3O4, Fe2O3

Aluminum: Al2O3

Copper: Cu2O CuOCopper: Cu2O, CuOStainless steel: CrO

Beilby layer: melting & surface flow-> rapid quenchingy y g p q gWork-hardened layer: residual stress

Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley

4

Surface textureFlaw (흠)/ defect (결함), lay (가공무늬), roughness (거칠기), waviness (파상도)


5

Surface roughnessSurface profilometers (표면거칠기 측정기)


6

Ra and Rqa q

Arithmetic mean value arithmetic ave. (AA) ( )center-line ave. (CLA)

Root-mean-square ave. (RMS)11⋅⋅⋅+++∫∑yyyy ln

db

21

222222

01

11

11

⎥⎤

⎢⎡==

⋅⋅⋅++++=

==+++

=

∫∑

∫∑=

dxyyyyyyR

dxyl

ynn

yyyyR

ln

idcba

ii

dcbaa

Rough surface: Lower precision short fatigue life higher electrical & thermal contact

01

⎥⎦⎢⎣ ∫∑=

dxyl

ynn

Ri

iq

Lower precision, short fatigue life, higher electrical & thermal contact resistance, lower corrosion resistance, better painting & coating, lower cost


7

Atomic Force Microscope (AFM) Tip

piezoresistor region PZT regionTip

High doping region

Before PZT process After PZT process

8

FrictionAdhesion theory of friction (응착이론)

Intimate contact of asperities creates an adhesive bond

Friction coefficient (마찰계수)AF r ττμ ===

, )( =k

mfactorshearfriction iτ

hardness

AN r

τμ

σσμ

=

===

2.03

3

2/) (

≅==

=

Y

Y

h d

Ystressyieldshearkk

τμ

577.03

3

===Y

YYhardness

στμ


9

Measuring FrictionRing compression test

5)39(4

10)1530(4

2222 −=−= IDvolume ππ

4.009.0

)%(1310015

1315

44

==

=×−

=

mand

decreaseIDinchange

μ 4.0 09.0 mandμ


10

Wear (1)Progressive loss of material from a surface

Adhesive wear (응착마멸)a surface

LWA h d lp

LWkV3

=Archard wear law

ilbklbW

kinV

/700170/120200

)2.4 tablefrom(10001.0

22

3

3

==

=−

ftinkWVpL

inlbmmkgp

2132560)200)(10(

)700,170)(001.0)(3(3/700,170/120

3

22

====

==

−Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley

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Wear (2)Abrasive wear

Corrosive wearCorrosive wearFatigue wear


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Lubrication

4 i f l b i ti G t i d f t4 regimes of lubrication Geometric defects


13

Surface Treatment (1)Shot peening, water-jet peening, laser peeningRoller burnishing (surface rolling)Roller burnishing (surface rolling)Cladding (clad bonding)Mechanical platingp gThermal sprayingSurface texturing


14

Surface Treatment (2)Vapor deposition (CVD/PVD/ Ion implantation)Electroplating/ electroless platingp g p gElectroformingAnodizingDiamond coatingg


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Cold spray (1)• High deposition rate at low temperature• Accelerated powder particles are sprayed onto substrate.• Fabrication type : constructive process• Typical substrate materials : metal

Schematic diagram

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Cold spray (2)Repair of damaged mold

1. Mold fabrication 3. Deposition of particles

2. Damaged mold 4. Machining mold surface

5. Repaired mold

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Nano particle deposition system (NPDS)• High deposition rate at room temperature• Aerosol with particles is accelerated by a gas

flow and sprayed onto substrate.• Fabrication type : constructive process• Typical substrate materials : metal, ceramic

Fabrication envelop

yp

0 1

Mn-Zn ferrite coating on Al 6061 with niddles

0.17mm

0.1mm 0.46mm1.03mm

2 5 μm 250 nm

TiO2 coating on Stainless steel

2.5 μm 250 nm

Schematic diagram

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MeasurementLength: dial indicator, LVDTStraightness : autocollimatorsStraightness : autocollimatorsFlatness: interferometryRoundness: total indicator reading (TIR), full indicator movementP filProfileCoordinate measuring machines (CMM) and layout machinesGagesgMicroscopes

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Precision & AccuracyAccuracy(정확도)

degree of conformity of adegree of conformity of a measure to a standard or a true value(closeness to the true value,

Probability

density δm

Probability

density δm

δm)

Precision(정밀도)Precision(정밀도)the degree of refinement with which an operation is performed

σ

or a measurement stated(size of standard deviation, σ)

ValueTrue value ValueTrue value

20

Precision & Accuracy – example

AccurateNot precise

AccuratePrecise

PreciseNot accurate

21

Dimensional Tolerance


22

Quality AssuranceNormal (Gaussian) Distribution

)()()()(

,2222

minmax

321

−=

+⋅⋅⋅+++=

xxRRangen

xxxxx n

1)()()()( 22

32

22

1

−−+⋅⋅⋅+−+−+−

=n

xxxxxxxx nσ

Control Chart

RAxxLCLRAxxUCLx 2

3)(lmitcontrolLower3)(lmit controlUpper +=+=

σ

σ

Control Chart

RAxxLCLx 23)(lmitcontrolLower −=−= σ

Six sigma (3~4 ppm)ISO 9000 (quality management & (q y gquality assurance)ISO 14000 (environmental management)management)


23

Control Chart

3R

4

RRDLCLRDUCLR

=

=

2dR

=σ


24

Process Capability Indices

LSLUSLProcess Capability Index, Cp

xp

LSLUSLCσ6−

=

Minimum acceptable value for Cp is 1Desirable value : 1 ~ 2

σ3±USL-LSL ①

USL-LSL ②

USL-LSL ①

USL-LSL ②Desirable value : 1 2

Process Capability Index, Cpk

−=

−=

LSLZUSLZx

xLSL

x

xUSL σ

μσ

μ

)( , minmean process:

min −=

ZZorZZ LSLUSL

xμ

0.13min ≥=

ZC pk

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Process Capability Indices - exampleLSL USL

σx=10

130100 190

130190

130100 190

610

130190

=

−=USLZ

3 )3( , 6minmin

=

−−=Z

10130100

6 −

=LSLZ 1.033==pkC

3 −=

Chapter 4. Surfaces, Tribology, Dimensions Inspection & … · 2018. 1. 30. · 4 4 6 . 3 0 5 A M A...

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Transcript of Chapter 4. Surfaces, Tribology, Dimensions Inspection & … · 2018. 1. 30. · 4 4 6 . 3 0 5 A M A...