Materials processing Types of manufacturing …drgregsmaterialsweb.com/Materials processing s2010...
Transcript of Materials processing Types of manufacturing …drgregsmaterialsweb.com/Materials processing s2010...
Materials processing Metal parts undergo sequence of processes Primary ‐ alter the (“raw”) material’s basic shape or form.
Sand casting Rolling Forging Sheet metalworking
Secondary ‐ add or remove geometric features from the basic forms
Machining of a brake drum casting (flat surfaces) Drilling/punching of refrigerator housings (sheet metal) Trimming of injection molded part flash
Tertiary ‐ surface treatments Polishing Painting Heat‐treating Joining
Making a “thingo” Solid
Plastic deformation Cold Hot
Removal of material Sold state diffusion processes
Liquid Casting
Types of manufacturing processes
ExtrusionForgingRollingBar drawingWire drawing
Deformation
CentrifugalDie castingInvestmentPermanent moldSand casting
Casting
BendingBlankingDrawingPunchingShearingSpinning
SheetMetal
Blow moldingCastingCompression moldingExtrusionInjection MoldingThermoformingTransfer molding
PolymerProcesses
BoringDrillingFacingGrindingMillingPlaningTurningSawingECM, EDM
Machining
AnodizingHoningPaintingPlatingPolishing
Finishing
AutomatedBondingBrazingManualRivetingSolderingWelding
Assembly
ManufacturingProcesses
How is the input material changed?
Making a “thingo” Solid
Plastic deformation Metals Ceramics Polymers??
What properties allows us to do this?
Structural Metals‐Properties Hardness Brittleness Malleable
A metal that can be hammered, rolled or pressed into various shapes without cracking or breaking
Ductility Property of metal that allows it to be permanently drawn, bent, or twisted into various shapes without breaking
Elasticity Toughness “plastic clays” Binders added to ceramics powders Structural Metals‐Selection Factors Strength
5 factors effecting strength are tension, compression, shear, bending & torsion
Types of manufacturing processes
FPDREDFSRREDFFMSm S CIna
wGGSO
FABRICATION MPart / Mfg. ProceDeformation proRolling Extrusion Drawing Forging Solid – Plastic deRolling (of ductileRolling Extrusion Drawing Forging (closed‐dFORMING TEMPMETAL FABRICATSintering – metals/ceramics
Solidification
Crystals and grain our case of soand meet each o
The resulwe call these “cryGrain Growth Grains Solidification: LetOne of the most
spontaneexisting p
METHODS‐solidess Consideratioocesses
eformation e materials)
die) ERATURE TION METHODS‐
ns lidifying materiaother t is no pretty cryystals” grains
t’s Make It Crystimportant phas
eous formation ophase
ns
‐Liquid
als the individua
ystal shapes
tal Clear! e changes of a new phase w
l crystals grow
within a pre‐
In
PBpcN
HN
N∆DHT
W
E
nvolves nucleatiosubseque
Phase transformBegin with the apphase (NUCLEATchange is compleNote:
new solidnew solid
Homogenous NuNucleation occur
replacemdecrease existencein an incr
Nucleation and G∆T? Degree of supercHomogeneous NTwo examples of
are know
Cu with homoge
Ni supersmall unand sma
Why only these celastic e
Everything else:
on ‐ initiation of tent growth of nuations ppearance of veTION) which thenete
d phase from an d phase from an ucleation rring in a perfect
ment of one phasin free energy
e of a surface betrease in energy
Growth
cooling (undercoucleation: examf homogeneous wn.
1‐3% Co can beeneously.
ralloys will precindercoolings becall interfacial enecases? Small intenergy differenceheterogeneous!
the formation ofucleus into crysta
ery small particlen GROW until th
existing liquid pexisting solid ph
tly homogenousse by another re
tween the two p
ooling) mples nucleation in th
heat treated to
pitate Ni3Al homcause of the smaergy. terfacial energy, e.
f a solid als
es of the new he phase
phase hase
s material sulting in a
phases results
e solid state
precipitate Co
mogeneously at all lattice misfit
and small
Heterogeneous Nucleation In practice, homogenous liquids rarely exist nuclei formed at a foreign surface
container wall, particles, structural imperfections can show r*hetero = r*homo sinδ
where δ is a function of the contact angle Practical consequences of solidification From this graph we can see:
low T solidification will lead to small grain growth higher T to large grains
Solid State Heterogeneous Nucleation Heterogeneous nucleation must occur on some substrate: grain boundaries triple junctions dislocations (existing) second phase particles Consider a grain boundary: why is it effective? Answer: by forming on a grain boundary, an embryo can offset its “cost” in interfacial energy by eliminating some grain boundary area. Columnar growth Consequences Large ingots (which will cool slowly) require additives to induce heterogeneous nucleation if fine grain size is desired Other problems also encountered
first part of ingot to solidify is? the next? and remember, on solidification most liquids shrink (can you think of an exception?)
T1
T2
Rate
Tem
p
Growth Rate, G
Nucln Rate, N
HKb
Nhabcd CSDInSDInMCDP
M
How do we avoidKeep the top of tbefore the rest o
often by aexothermdie castin
New grains in thehardened brass a) deformed strub) new grains nuc) more grains nud) complete recr
Casting ProcesseSand casting Die casting nvestment castiSand casting (cloDie casting/Injecnvestment castiMachining Composites Depend on the mParticles and sho
Many of tinChDi
Much technologyPultrusio
d this? the ingot hot, soof the casting adding compounmally ng e solid state ‐ re
ucture (note the cleating along sucleated ystallisation
es
ng osed‐mold) ction moulding ng/lost wax
matrix and reinfoort fibres the techniques wjection mouldinhopped gun ie casting(squee
y relies on placinn
o the surface doe
nds that decomp
crystallisation of
slip lines!) lip planes
orcement
we have looked ng/resin transfer
eze casting)
ng fibres
es not solidify
pose
f strain
at, r moulding
Die casting/
P
Investmen
Wax patteris cast
Wax removby meltin
g/Injection mould
Parting line
Plunger
Sprue
Stationary die
Moltenmetal
nt casting/lost w
rn
vedng
Molten metal solidifies in cast
Ceramrem
Ceram(harden4-part pattern tree
ingMoving
die
Ejector pins
wax
mic mold is moved
mic moldned slurry)
Filament winding Hand lay up
Vacuum bag SUMMARY –
• Consider the properties of the material • Can it be plastically deformed? • If not can we make it so?
• Ceramics for example • Do we need to heat it up?
• Consider the required properties of the “thingo” • Do we need to post‐heat treat to remove
properties we have introduced in forming? • Can we use cold working to produce a stronger
“thingo”? • Cold drawn copper pipe
• Does it need post‐mechanical treatment? • Remove parting lines • Surface treatment • Machining