Chapter 4. Surfaces, Tribology, Dimensions Inspection & … · 2018. 1. 30. · 4 4 6 . 3 0 5 A M A...
Transcript of 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)
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
5
Surface roughnessSurface profilometers (표면거칠기 측정기)
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
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
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
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
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
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
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
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
11
Wear (2)Abrasive wear
Corrosive wearCorrosive wearFatigue wear
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
12
Lubrication
4 i f l b i ti G t i d f t4 regimes of lubrication Geometric defects
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
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
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
14
Surface Treatment (2)Vapor deposition (CVD/PVD/ Ion implantation)Electroplating/ electroless platingp g p gElectroformingAnodizingDiamond coatingg
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
15
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
16
Cold spray (2)Repair of damaged mold
1. Mold fabrication 3. Deposition of particles
2. Damaged mold 4. Machining mold surface
5. Repaired mold
17
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
18
MeasurementLength: dial indicator, LVDTStraightness : autocollimatorsStraightness : autocollimatorsFlatness: interferometryRoundness: total indicator reading (TIR), full indicator movementP filProfileCoordinate measuring machines (CMM) and layout machinesGagesgMicroscopes
19
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
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
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)
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
23
Control Chart
3R
4
RRDLCLRDUCLR
=
=
2dR
=σ
Ref.S. Kalpakjian, "Manufacturing Processes for Engineering Materials",3rd/4th ed. Addison Wesley
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
25
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 −=